{"id":158,"date":"2007-11-17T12:35:06","date_gmt":"2007-11-17T12:35:06","guid":{"rendered":"https:\/\/www.garfnet.org.uk\/cms\/commonly-used-radio-terminology\/"},"modified":"2026-09-05T17:45:35","modified_gmt":"2026-09-05T17:45:35","slug":"commonly-used-radio-terminology","status":"publish","type":"page","link":"https:\/\/garfnet.org.uk\/cms\/tables\/radio-frequencies\/commonly-used-radio-terminology\/","title":{"rendered":"Commonly used radio terminology"},"content":{"rendered":"<p><b>This is a brief list of some commonly used terms and expressions used by radio enthusiasts and resellers. It is not an exhaustive list and many of the terms can be found in greater detail in the Wikipedia.<\/b><\/p>\n<blockquote>\n<ul>\n<li><b><a title=\"Wikipedia\" href=\"http:\/\/www.wikipedia.org\" target=\"_blank\" rel=\"noopener\">http:\/\/www.wikipedia.org<\/a><br \/>\n<\/b><\/li>\n<\/ul>\n<\/blockquote>\n<p>You can use your browser\u2019s <em>Find on Page <\/em>feature to search for a term on the current page.&nbsp;Click any column heading to sort the entries by that column. Click it again to reverse the sort order.<\/p>\n<div class=\"garf-info-2-table-wrap\"><table id=\"garf-info-2-1\" class=\"garf-info-2-table mtr-table mtr-thead-th\"><thead><tr><th scope=\"col\" class=\"garf-info-2-sortable mtr-th-tag\" aria-sort=\"none\" data-mtr-content=\"term\"><div class=\"mtr-cell-content\"><a href=\"\/cms\/wp-json\/wp\/v2\/pages\/158?garf_sort=term&amp;garf_dir=asc&amp;garf_page=1&amp;garf_size=1000\" class=\"garf-info-2-sort\">term<span class=\"garf-info-2-sort-indicator\" aria-hidden=\"true\"><\/span><\/a><\/div><\/th><th scope=\"col\" class=\"garf-info-2-sortable mtr-th-tag\" aria-sort=\"none\" data-mtr-content=\"meaning\"><div class=\"mtr-cell-content\"><a href=\"\/cms\/wp-json\/wp\/v2\/pages\/158?garf_sort=meaning&amp;garf_dir=asc&amp;garf_page=1&amp;garf_size=1000\" class=\"garf-info-2-sort\">meaning<span class=\"garf-info-2-sort-indicator\" aria-hidden=\"true\"><\/span><\/a><\/div><\/th><\/tr><\/thead><tbody><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">10 MHz Reference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A commonly used external frequency reference for synchronising radio equipment and test instruments.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">50 Ohm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A common characteristic impedance used by radio-frequency equipment and many amateur radio systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">75 Ohm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A common characteristic impedance used in broadcast, television and some other RF systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A Index<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A daily measure derived from geomagnetic observations and used as an indicator of longer-term geomagnetic activity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ACARS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Aircraft Communications Addressing and Reporting System \u2013 a digital data communication system used by aircraft and ground stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Active Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna incorporating an electronic amplifier, allowing a physically small antenna to provide useful output to a receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Adjacent Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A channel immediately above or below the desired channel frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Adjacent Channel Interference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference caused by a strong signal on a nearby radio channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Adjacent Channel Rejection<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a receiver to reject an unwanted signal on a nearby channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Aerial<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another name for an antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic Gain Control \u2013 a circuit that automatically adjusts receiver gain as signal strength changes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Attack<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The speed at which an AGC system reduces receiver gain after detecting a strong signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Fast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An AGC setting that responds quickly to changes in received signal strength.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Hang<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An AGC mode in which reduced receiver gain is held for a period after a strong signal disappears.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Pumping<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An audible effect caused by rapid AGC gain changes, often producing noticeable changes in background noise or audio level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Release<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The speed at which an AGC system restores receiver gain after a strong signal decreases or disappears.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Slow<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An AGC setting that responds more gradually to changes in received signal strength, often giving smoother audio with fading signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Threshold<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The signal level at which an automatic gain control system begins to adjust receiver gain.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AGC Time Constant<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The response characteristic determining how quickly an automatic gain control system changes receiver gain.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AIS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic Identification System \u2013 a maritime radio-based system that exchanges vessel identification, position, course and other information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AM<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amplitude Modulation \u2013 a method of encoding information by varying the amplitude of a carrier wave. AM is commonly used on longwave, medium-wave and shortwave broadcasting, and is also used for aviation communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AM Broadcast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio broadcasting using amplitude modulation, commonly used on longwave and medium-wave frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AM Sidebands<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The upper and lower frequency components produced when an AM carrier is modulated. These sidebands contain the modulation information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio service in which licensed operators use designated frequencies for communication, experimentation, education and technical activities.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device used to transmit or receive radio-frequency electromagnetic waves.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Diversity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reception technique using multiple antennas and selecting or combining their signals to improve reliability.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Efficiency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The proportion of radio-frequency power supplied to an antenna that is actually radiated as electromagnetic energy.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Farm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A site containing multiple antennas, commonly associated with broadcasting or communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Gain<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measure of how effectively an antenna concentrates transmitted or received energy in a particular direction compared with a reference antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Impedance<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The electrical impedance presented by an antenna at a particular frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Lobe<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A region of relatively strong radiation or reception in an antenna radiation pattern.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Mast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A pole, tower or supporting structure used to elevate an antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Matching<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of obtaining a suitable impedance relationship between an antenna, transmission line and transmitter or receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Polarisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The orientation of the electric field of a radio wave, commonly described as vertical, horizontal or circular.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Preamp<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A low-noise amplifier placed near an antenna to increase weak received signals before feedline losses.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Resonance<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where an antenna has a suitable relationship between inductive and capacitive reactance at a particular frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Rotator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A motorised device used to turn a directional antenna toward a selected direction.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Tuner<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device used to transform the impedance presented by an antenna system so that it more closely matches the transmitter or transmission line.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Tuning Unit<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another name for an antenna tuner.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Approach Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio frequency used by aircraft to communicate with an air traffic control approach service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ATC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Air Traffic Control \u2013 a service responsible for managing aircraft movements and maintaining safe separation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ATIS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic Terminal Information Service \u2013 a recorded aviation broadcast providing information such as weather, runway and airport conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Atmospheric Ducting<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A propagation condition in which atmospheric layers guide radio waves and allow unusually long-distance VHF, UHF or microwave communication.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Atmospheric Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Natural radio noise produced by sources such as lightning and electrical storms.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Atmospheric Static<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Natural radio-frequency noise, particularly from lightning and thunderstorms.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ATU<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Antenna Tuning Unit \u2013 a device used to match an antenna system to a transmitter or transmission line.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio AGC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic gain control applied to an audio signal to maintain a relatively consistent listening level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio Clipping<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Distortion caused when an audio signal exceeds the maximum level that an amplifier or processing stage can reproduce.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio Distortion<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted changes introduced into an audio signal by a receiver, transmitter, amplifier or other equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter applied to received audio to reduce unwanted frequencies or improve intelligibility.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio Gain<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The amplification level applied to an audio signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio Gain Control<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A control used to adjust the level or amplification of an audio signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Aurora<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A natural luminous phenomenon caused by charged particles interacting with Earth's upper atmosphere. It can also influence VHF radio propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Auroral Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio propagation associated with auroral regions that can enable unusual long-distance VHF communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic Notch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver function that automatically detects and suppresses interfering tones or carriers.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Aviation Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The VHF frequency range used for civil aviation voice communications, normally using AM.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Azimuth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The horizontal direction from an observer toward a location, normally measured in degrees from north.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Backlight<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Illumination provided behind or around a radio display or controls to improve visibility in low light.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Balun<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device used to connect balanced and unbalanced radio-frequency circuits or transmission lines.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Band Plan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A published arrangement showing how frequencies within a radio band are intended to be used.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Band Scan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scanning function that searches through a defined range of frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Band-Pass Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter that allows a specified range of frequencies to pass while attenuating frequencies outside that range.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bandwidth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of frequencies occupied by a signal or allowed through a receiver or filter, normally expressed in hertz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bandwidth Control<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver control used to adjust the width of the received signal passband and improve selectivity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Base Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A fixed radio station operating from a permanent location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Battery Saver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A feature that reduces portable radio power consumption by placing parts of the receiver into a low-power state when inactive.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Baud<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The number of symbols transmitted per second in a communication system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beacon<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmitter that periodically or continuously sends an identifying signal or information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beacon Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A designated frequency used by a beacon transmitter.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beacon Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of listening for known beacons to assess radio propagation conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beacon Network<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A collection of radio beacons used to provide identifying or propagation information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beamwidth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The angular width of the main lobe of an antenna radiation pattern, commonly measured between points 3 dB below the peak.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bearing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The direction from one location toward another, normally expressed in degrees relative to north.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beat Note<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An audible tone produced when two signals with slightly different frequencies are mixed.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">BER<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bit Error Rate \u2013 the proportion of received digital bits containing errors.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">BFO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Beat Frequency Oscillator \u2013 an oscillator used to create an audible beat note when receiving CW or SSB signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">BFO Pitch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The audio pitch produced by a beat frequency oscillator when receiving CW or SSB.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Birdie<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted internally generated signal appearing at a particular frequency in a receiver, often caused by oscillator harmonics or digital circuitry.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bitrate<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The amount of digital information transmitted or processed per second.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Blocking<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver condition where a strong unwanted signal reduces the ability to receive a weaker desired signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Break-In<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A method of operation allowing a transmitter to switch between transmit and receive during Morse code operation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Broadcast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmission intended to be received by multiple listeners rather than a single specified station.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Broadcast Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A frequency range allocated for radio broadcasting to the general public.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Broadcast Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of monitoring radio broadcasting services for reception, content or technical performance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Broadcast Schedule<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A timetable showing when a radio service is expected to transmit on particular frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Busy Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio channel on which a signal is currently being detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Busy Lockout<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A feature preventing transmission while another signal is detected on the selected channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Bypass Capacitor<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A capacitor used to provide a low-impedance path for unwanted high-frequency signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Cable Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The reduction in radio-frequency signal power as it travels through a transmission cable.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Calibration<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of checking and adjusting radio equipment against known standards.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Call Sign<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A unique sequence of letters, numbers or both used to identify a radio station or operator.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Callsign<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another spelling of call sign, the identifying letters or numbers assigned to a radio station or operator.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Capture Ratio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The minimum strength difference between two FM signals that allows the receiver to effectively capture the stronger one.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio-frequency signal that is modulated to carry information such as speech, music or digital data.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier Detect<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver indication showing that a signal above a defined threshold has been detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The nominal frequency of a radio-frequency carrier before modulation is applied.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier Reinsertion<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of generating a local replacement carrier in a receiver to demodulate a suppressed-carrier signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier Reinsertion Oscillator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A locally generated oscillator used to provide a replacement carrier when receiving suppressed-carrier modes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier Squelch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A squelch system that opens receiver audio when a received RF signal exceeds a preset strength.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier-Off<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition in which a radio-frequency carrier is absent.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Carrier-On<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition in which a radio-frequency carrier is present.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CB Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Citizens Band radio \u2013 a short-range two-way radio service intended for personal and general communications on designated frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Centre Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The nominal frequency at the centre of a channel, filter passband or modulated signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ceramic Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter using ceramic resonators to provide a defined frequency response and bandwidth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A designated radio frequency or range of frequencies used for a particular communication service or transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Allocation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The assignment of specific radio frequencies or frequency ranges to particular services or users.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Bandwidth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The total frequency range allocated to or occupied by a radio channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Busy<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition in which a radio channel contains detectable radio activity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Busy Indicator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A display, light or icon showing that a radio receiver detects activity on the current channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Guard<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A general term for tone or digital signalling used to control access to a radio channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Channel Spacing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency separation between adjacent radio channels. Suitable spacing helps reduce interference between neighbouring channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Characteristic Impedance<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The characteristic impedance of a transmission line, commonly 50 or 75 ohms in radio systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Chirp<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted change in transmitter frequency occurring during the beginning of a transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Circular Polarisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Polarisation in which the electric field rotates as the wave travels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Clipping<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Distortion caused when an amplifier or signal-processing stage is driven beyond its available signal range.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Co-channel Interference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference caused by two or more stations using the same or very similar frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Coax<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Common abbreviation for coaxial cable.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Coaxial Cable<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmission line consisting of a central conductor surrounded by dielectric insulation and an outer conductive shield.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Codec<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A system or algorithm used to encode and decode digital audio or other information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Common-Mode Choke<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device designed to suppress unwanted common-mode currents on cables.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Common-Mode Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted electrical noise appearing in the same direction on multiple conductors.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Connector Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal loss caused by connectors, adapters and junctions in an RF system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Control Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A channel carrying signalling information used by a trunked radio system to manage communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Counterpoise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A conductive wire or structure used as an RF reference or return path for an antenna system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Courtesy Tone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A short tone transmitted by some repeaters to indicate that a transmission has ended and the channel is available.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Coverage Area<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The geographical area in which a radio transmission can be received at an acceptable level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Coverage Prediction<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An estimate of the geographical area expected to receive a radio transmission at a specified quality.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CRC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Cyclic Redundancy Check \u2013 an error-detection method used to determine whether digital data has been corrupted.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Critical Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The highest frequency that an ionospheric layer can return to Earth when a signal is transmitted vertically.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Cross-Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio operating method in which a station receives on one frequency band and transmits on another.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Crystal Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A highly selective filter using quartz crystal resonators to provide a narrow and stable frequency response.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Crystal Oscillator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An oscillator using a quartz crystal to provide a highly stable reference frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CTCSS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Continuous Tone-Coded Squelch System \u2013 a system using low-frequency tones to control access to a compatible receiver or repeater.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CTCSS Tone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A sub-audible tone transmitted with a radio signal to control access to compatible equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Cutoff Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency defining the transition between a filter passband and stopband according to a specified criterion.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CW<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Continuous Wave \u2013 a radio transmission method traditionally used for Morse code, in which a carrier is switched on and off to form dots and dashes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">CW Pitch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The audible tone selected for reception of a CW signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">D Layer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The lowest major ionospheric region involved in HF propagation. It can strongly absorb lower-frequency signals, especially during daylight.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DAB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Audio Broadcasting \u2013 a digital radio broadcasting system transmitting audio and data using digital modulation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DAB+<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An enhanced version of DAB using the HE-AAC audio codec for more efficient digital audio broadcasting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Data Burst<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A short, discrete transmission of digital information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Data Rate<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The rate at which digital information is transmitted, normally expressed in bits per second.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">dBd<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decibels relative to a half-wave dipole antenna, used to express antenna gain.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">dBi<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decibels relative to an ideal isotropic antenna, commonly used to express antenna gain.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">dBm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decibels relative to one milliwatt, commonly used to express RF power levels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">dB\u00b5V<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decibels relative to one microvolt, commonly used to describe RF signal levels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DCS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital-Coded Squelch \u2013 a system using a digital code to control receiver squelch or repeater access.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DCS Code<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A digital code used to control access to compatible radio receivers or repeaters.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">De-emphasis<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver process that reduces higher audio frequencies after FM reception to complement transmitter pre-emphasis.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">De-multiplexing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of separating combined signals or services from a multiplexed transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dead Air<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period during which a radio channel or station carries no intended programme audio or information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dead Carrier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmitted RF carrier containing little or no intended modulation or information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dead Spot<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An area where a normally usable radio signal becomes unusually weak or unavailable.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decibel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A logarithmic unit used to express ratios of power, voltage, signal level and other quantities.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Decoupling<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of preventing unwanted electrical or RF signals from passing between circuits through shared connections.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Demodulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of recovering information from a modulated radio-frequency signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Desensitisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reduction in receiver sensitivity caused by a strong nearby signal or other interference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital AGC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic gain control implemented using digital signal processing.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Audio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio represented as digital data rather than as a continuously varying analogue signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Mode<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio communication mode in which information is transmitted using digitally encoded signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Modulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A modulation method in which digital information is represented by controlled changes in a radio-frequency carrier.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dipole<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A simple antenna consisting of two conductive elements arranged around a feed point. A half-wave dipole is approximately half a wavelength long.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Directional Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna designed to transmit or receive signals more strongly in particular directions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Discriminator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A circuit used in FM receivers to convert frequency variations into corresponding voltage variations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Distress Signal<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio signal indicating that a person, vessel, aircraft or station is in serious danger and requires assistance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Doppler Shift<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A change in apparent received frequency caused by relative movement between transmitter and receiver or by movement of a reflecting medium.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Downlink<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmission from a satellite or other elevated system to a receiving station on Earth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DSC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Selective Calling \u2013 a digital signalling system used particularly in maritime communications for automated calling and distress alerts.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DSP<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Digital Signal Processing \u2013 the use of digital computation to filter, analyse, demodulate and otherwise process signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DSP Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A digitally implemented filter used to control bandwidth, remove interference or improve reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dual Receive<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function allowing a radio to monitor two frequencies or channels, either simultaneously or alternately depending on the equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dual Watch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function that monitors two selected frequencies or channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dummy Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another term sometimes used for a dummy load.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dummy Load<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A non-radiating load designed to absorb transmitter power and provide a suitable impedance for testing.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Duplex<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A communication method using separate transmit and receive frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DX<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Long-distance radio communication or reception. A DX station is a distant station.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DX Listener<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A shortwave listener who concentrates on receiving distant radio stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DX Opening<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period of favourable propagation allowing reception or communication with distant stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">DXing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The activity of attempting to receive or contact distant radio stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Dynamic Range<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range between the weakest useful signal a receiver can detect and the strongest signal it can handle without unacceptable degradation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">E Layer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An ionospheric region above the D layer that can reflect some radio signals. Sporadic E occurs in this region.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ECSS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Exalted Carrier Single Sideband \u2013 a reception technique using a locally generated carrier together with a selected sideband to improve reception of AM signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EHF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Extremely High Frequency \u2013 radio frequencies from 30 GHz to 300 GHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EIRP<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Effective Isotropic Radiated Power \u2013 the equivalent power that would need to be supplied to an ideal isotropic antenna to produce the same maximum power density.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Electromagnetic Interference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference caused by unwanted electromagnetic energy from another source.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Electromagnetic Spectrum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The complete range of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Elevation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The angle above the horizon toward a target such as a satellite or radio source.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ELF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Extremely Low Frequency \u2013 radio frequencies from 3 Hz to 30 Hz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ELT<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Emergency Locator Transmitter \u2013 an aviation emergency transmitter intended to help locate an aircraft after an accident or emergency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EME<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Earth-Moon-Earth \u2013 another name for moonbounce communication.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Emergency Beacon<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmitter designed to send an emergency or distress signal to aid rescue or location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Emergency Broadcast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmission used to distribute urgent information concerning emergencies or public safety.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Emergency Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A designated frequency used for emergency or distress communications within a radio service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EMI<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Electromagnetic Interference \u2013 unwanted electromagnetic energy that disrupts electronic equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">End-Fed Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna fed at or near one end rather than at its centre.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ensemble<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">In DAB, a group of digital radio services transmitted together within a single multiplex.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Envelope Detector<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A detector commonly used for AM that extracts the varying envelope of the modulated carrier.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EON<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Enhanced Other Networks \u2013 an RDS feature allowing a receiver to obtain information about traffic or other programme services on different networks.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">EPIRB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Emergency Position-Indicating Radio Beacon \u2013 a maritime distress beacon designed to transmit an emergency signal and, depending on the system, position information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ERP<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Effective Radiated Power \u2013 transmitter power taking antenna gain and system losses into account in a specified direction.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Error Correction<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Techniques used in digital systems to detect and correct errors introduced during transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">External Reference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A stable frequency signal supplied from outside a radio to improve frequency accuracy and stability.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">External Speaker<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A separate loudspeaker connected to a radio receiver or transceiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">F Layer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The upper major ionospheric region responsible for much long-distance HF propagation. It can divide into F1 and F2 regions during daylight.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Factory Reset<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function that restores a radio to its original manufacturer settings.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Fade Margin<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The amount of signal strength available above the minimum required level, providing protection against fading.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Fade-In<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A gradual increase in received signal strength or audio level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Fade-Out<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A gradual reduction in received signal strength or audio level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Fading<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Variation in received signal strength caused by changes in radio propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Far Field<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The region sufficiently far from an antenna where the radiation pattern is substantially established.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FEC<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Forward Error Correction \u2013 additional information transmitted so that some errors in received digital data can be detected and corrected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Feedline<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmission line carrying RF energy between radio equipment and an antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ferrite Bead<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A small ferrite component used to suppress unwanted high-frequency electrical noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ferrite Choke<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A component or assembly using ferrite material to suppress unwanted radio-frequency currents.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ferrite Rod Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A compact antenna using a coil wound around a ferrite rod, commonly used in medium-wave broadcast receivers.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Field Strength<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The strength of an electromagnetic radio signal at a particular location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Field Strength Meter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An instrument used to measure the strength of a radio signal at a location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Fine Tuning<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Small adjustments to the operating frequency used to accurately tune a signal, particularly useful for SSB and CW.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Firmware<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Software stored inside a radio device that controls its hardware and operating functions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Firmware Update<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An update to the software controlling a radio device.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">First Hop<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The first propagation segment between a transmitter and the point where an ionospherically propagated signal returns to Earth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Modulation \u2013 a method of encoding information by varying the frequency of a carrier wave. FM is widely used for VHF broadcasting and two-way communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM Broadcast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio broadcasting using frequency modulation, commonly used in the VHF broadcast band.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM Capture Effect<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The tendency of an FM receiver to favour the stronger of two signals received on or near the same frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM Detector<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A circuit that converts frequency variations in an FM signal into a corresponding audio or data signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM Deviation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The amount by which the instantaneous frequency of an FM signal moves above and below its centre frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FM Stereo<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A system for transmitting left and right audio channels using an FM broadcast signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Forward Power<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency power travelling from a transmitter toward an antenna or other load.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FOT<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency of Optimum Transmission \u2013 a practical operating frequency normally chosen below the predicted MUF.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Free-Space Path Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The theoretical reduction in signal strength caused by spreading of a radio wave through free space.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Free-Space Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ideal radio propagation through unobstructed space without reflections or environmental losses.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The number of complete cycles of a periodic signal occurring each second. Frequency is measured in hertz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Accuracy<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">How closely an actual operating frequency corresponds to its specified or intended frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Allocation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The designation of a frequency band for use by one or more radio communication services.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Assignment<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The designation or authorisation of a particular radio frequency for a specific station or service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A defined range of radio frequencies identified by its limits or by a conventional name such as HF, VHF or UHF.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Coordination<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of selecting and managing frequencies to reduce interference between radio systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Display<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A display showing the currently selected or tuned radio frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Drift<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted change in operating frequency over time.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Memory<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver memory location containing a stored operating frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of observing or listening to activity on specified radio frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Reference Lock<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where a radio oscillator or synthesizer is locked to a stable reference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Response<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of frequencies an audio or radio system can reproduce or process and the relative response at each frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Stability<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a frequency source to maintain its frequency despite temperature, voltage, ageing and other changes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Synthesizer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An electronic circuit capable of generating many selectable frequencies from one or more stable reference frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Front-End Overload<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition in which a strong signal overwhelms the input stages of a receiver, potentially producing distortion or false signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Front-to-Back Ratio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measurement comparing antenna response in the main direction with response in the opposite direction.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">FSK<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency Shift Keying \u2013 a digital modulation method in which different frequencies represent different digital states or symbols.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Geomagnetic Activity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The level of disturbance in Earth's magnetic field caused by solar activity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Geomagnetic Storm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A disturbance in Earth's magnetic environment caused by solar activity that can significantly affect HF propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Gigahertz<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">One billion hertz, abbreviated GHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">GMDSS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Global Maritime Distress and Safety System \u2013 an international system using radio and satellite communications for maritime distress and safety.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">GPSDO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">GPS Disciplined Oscillator \u2013 a highly stable frequency source disciplined using timing information from a satellite navigation system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Great Circle<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The shortest surface path between two points on a sphere, commonly used when considering long-distance radio paths.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Greyline<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The boundary region between daylight and darkness around the Earth. Propagation can sometimes be enhanced along this region.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Greyline Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Long-distance HF propagation occurring along or near the boundary between daylight and darkness.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Control<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An air traffic control service managing aircraft and vehicles on airport movement areas.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Loop<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted electrical connection between equipment grounds that can introduce circulating currents, hum or interference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Plane<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A conductive surface forming part of an antenna system, commonly used with vertical antennas.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Radials<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Conductive wires arranged around the base of a vertical antenna to improve its RF ground system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station located on Earth that communicates with satellites, spacecraft or other remote systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ground Wave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio propagation in which a signal travels along or close to the Earth's surface.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Guard Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A frequency range separating channels or services to reduce interference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Guard Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A designated radio channel monitored for important, emergency or distress communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Guard Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A designated frequency monitored for distress or emergency communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Half-Wave Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna approximately half a wavelength long, such as a conventional dipole.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ham Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another name for amateur radio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Handheld Transceiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A small portable transceiver designed to be operated while held in the hand.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Harmonic<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A signal occurring at an integer multiple of a fundamental frequency. Unwanted harmonics can cause interference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Harmonic Distortion<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Distortion caused by the generation of unwanted harmonic frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Headphone Output<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An audio output connection provided by a receiver for headphones.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Hertz<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The unit of frequency equal to one cycle per second, abbreviated Hz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Heterodyne<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of mixing two frequencies together to produce new frequencies equal to their sum and difference.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">HF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">High Frequency \u2013 radio frequencies from 3 MHz to 30 MHz. HF is commonly associated with shortwave broadcasting and long-distance communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">High-Pass Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter that allows frequencies above a selected cutoff frequency to pass while attenuating lower frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Horizontal Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna whose main radiating element is oriented horizontally.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Horizontal Polarisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-wave polarisation in which the electric field is predominantly horizontal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Hum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low-frequency unwanted audio, commonly caused by mains-frequency interference or grounding problems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">IF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Intermediate Frequency \u2013 a fixed frequency used inside many receivers for filtering and amplification.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">IF Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter operating at a receiver intermediate frequency to determine bandwidth and selectivity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">IF Rejection<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a receiver to reject unwanted signals occurring at or near its intermediate frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">ILS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Instrument Landing System \u2013 an aviation navigation system providing guidance during approach to a runway.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Image Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted frequency that can also produce the receiver intermediate frequency and therefore appear as a false reception in a superheterodyne receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Image Rejection<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a receiver to reject unwanted signals at the image frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Insertion Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal loss caused by inserting a component such as a filter or connector into a signal path.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted signal or electrical disturbance that makes a desired radio signal harder to receive or decode.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference Margin<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The amount by which a desired signal exceeds an interfering signal or noise level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interference-Limited<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where reception quality is primarily limited by unwanted signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Intermodulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The creation of unwanted signals at new frequencies when two or more signals interact in a non-linear circuit.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">International Broadcaster<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A broadcaster transmitting programmes across national or regional boundaries.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Interval Signal<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A distinctive musical phrase, tone or other signal transmitted by a broadcaster before or between programmes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ionosphere<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A region of the upper atmosphere containing significant concentrations of charged particles. It strongly influences radio propagation, particularly at HF.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ionospheric Absorption<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reduction in radio signal strength caused by absorption of RF energy within the ionosphere.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ionospheric Layer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A region within the ionosphere with particular electrical characteristics affecting radio propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ionospheric Storm<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period of disturbed ionospheric conditions caused by solar or geomagnetic activity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">IP3<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Third-Order Intercept Point \u2013 a specification used to describe the linearity of RF amplifiers and receivers.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">IQ<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">In-phase and Quadrature \u2013 two components used to represent the amplitude and phase information of a radio signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Isotropic Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An ideal theoretical antenna radiating equally in all directions and used as a reference for antenna gain.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">K Index<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A numerical indicator of short-term geomagnetic activity used when assessing conditions affecting HF propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Key Clicks<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted short RF or audio transients produced when a Morse transmitter switches rapidly.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Keypad Entry<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Entering a frequency, channel or configuration using the controls on a radio keypad.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Kilohertz<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">One thousand hertz, abbreviated kHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">KiwiSDR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A network-connected software-defined radio platform commonly used to provide remote access to HF and other radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">L-Match<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An impedance matching network using reactive components arranged in an L configuration.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">LCD<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Liquid Crystal Display \u2013 a display technology commonly used in radios, scanners and other electronic equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">LF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low Frequency \u2013 radio frequencies from 30 kHz to 300 kHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Licence<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An official authorisation allowing operation of a radio transmitter under specified conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Licence-Free<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Describes a radio service that may be operated without an individual licence, subject to applicable regulations and equipment requirements.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Limiter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A circuit that restricts signal amplitude, commonly used in FM receivers to reduce the effect of amplitude noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Limiter Stage<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver stage that restricts amplitude variations, commonly used in FM reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Line of Sight<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A propagation path with a largely unobstructed direct path between transmitting and receiving antennas.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Linked Repeater<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A repeater connected to one or more other repeaters.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Listen Before Transmit<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of checking a radio channel for existing activity before transmitting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Listening Post<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A location primarily used for monitoring and receiving radio transmissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">LNA<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low Noise Amplifier \u2013 an amplifier used near the receiver input or antenna to increase weak signals with relatively little added noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Local Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency interference generated near a receiving location by electrical or electronic equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Local Oscillator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An oscillator inside a receiver that generates a frequency used for mixing with the incoming signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Local Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station primarily intended to provide coverage to a particular local geographical area.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Lockout<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scanner function that prevents a selected frequency or channel from being included in a scan.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Logbook<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A record of radio contacts or reception details.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Long Path<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The longer great-circle route between two locations around the Earth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Long Wire<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A wire antenna relatively long compared with the wavelength of the received signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Longwave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A commonly used term for radio transmissions in the LF range, particularly for broadcasting services below the medium-wave band.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Longwire Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A relatively long wire antenna commonly used for receiving or transmitting radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Loop Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna consisting of one or more loops of wire or conductor.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low Battery Alert<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A warning produced by a radio when battery voltage or remaining capacity becomes low.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low Noise Amplifier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An amplifier designed to increase weak RF signals while adding as little noise as practical.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Low-Pass Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter that allows frequencies below a selected cutoff frequency to pass while attenuating higher frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">LSB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Lower Sideband \u2013 the lower sideband component of an SSB transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">LUF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Lowest Usable Frequency \u2013 the lowest frequency expected to provide acceptable communication over a specified path, often limited by noise and absorption.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Magnetic Loop<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A small loop antenna designed primarily to respond to the magnetic component of a radio wave and often providing useful directional nulls.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Man-Made Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency interference generated by electrical equipment, vehicles, power supplies and other human-made sources.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Marine VHF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A VHF radio service used for communication between ships, boats and shore stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Matching Network<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A circuit used to transform one impedance into another in a radio-frequency system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mayday<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An internationally recognised distress call indicating grave and imminent danger requiring immediate assistance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Megahertz<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">One million hertz, abbreviated MHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Memory Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A stored receiver configuration containing a frequency and possibly other settings.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Memory Recall<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of retrieving a stored frequency or radio configuration.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Memory Scan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scanning function that checks only frequencies or channels stored in memory.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Meteor Scatter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation using ionised trails created by meteors in the upper atmosphere to reflect or scatter radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">MF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Medium Frequency \u2013 radio frequencies from 300 kHz to 3 MHz. The medium-wave AM broadcast band is located within this range.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mic Gain<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A control that adjusts the audio level supplied from a microphone to a transmitter.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Microphone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device that converts sound into an electrical audio signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Microvolt<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">One millionth of a volt. Receiver sensitivity and RF signal levels may be specified in microvolts.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Microwave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency electromagnetic waves commonly associated with frequencies above approximately 1 GHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Microwave Link<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A point-to-point communication link using microwave frequencies, usually with highly directional antennas.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mixer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A circuit that combines two frequencies and produces sum and difference frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mobile Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station installed in or carried by a vehicle or other mobile platform.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mode<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The particular transmission or reception method used by a radio system, such as AM, FM, SSB or CW.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Modem<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A device or system that modulates and demodulates signals to allow digital information to be transmitted over radio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Modulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of varying a radio-frequency carrier to encode information such as speech, music or digital data.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Modulation Depth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measure of the extent to which an AM carrier is varied by its modulation signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Modulation Index<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">In FM, a measure related to frequency deviation divided by the frequency of the modulating signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Monitor<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function allowing an operator to listen to transmitted or internally processed audio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Monitoring Receiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver used primarily to monitor radio frequencies or communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Mono<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Monaural audio consisting of a single audio channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Moonbounce<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio communication using the Moon as a natural reflector for radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Morse Code<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A communication code representing letters, numbers and punctuation using combinations of short and long signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">MUF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Maximum Usable Frequency \u2013 the highest frequency generally expected to support reliable ionospheric communication over a specified path.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Multi-Hop<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation in which a signal makes multiple ionospheric reflections or hops to reach a distant receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Multipath<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where a radio signal reaches the receiver by multiple propagation paths, potentially causing fading or distortion.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Multiplex<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A combined digital broadcast stream containing multiple radio services and associated data.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Multiplexing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of combining multiple signals or services into a single transmission channel.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Narrow\/Wide Switch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A control allowing the receiver to select between narrower and wider filtering, helping balance selectivity and audio quality.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Navigation Beacon<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio beacon transmitting signals used by aircraft, ships or other users for navigation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">NAVTEX<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A maritime information service that automatically broadcasts navigational and meteorological safety information to ships.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">NDB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Non-Directional Beacon \u2013 a radio navigation beacon used by aircraft to determine direction to the beacon.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Near Field<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The region close to an antenna where electromagnetic fields behave differently from the far-field radiation pattern.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Network Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio communication system in which stations or repeaters are connected through a communications network.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Networked SDR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A software-defined radio receiver accessible remotely over a computer network.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted random electrical or radio-frequency energy that can obscure or degrade a desired signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise Blanker<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver circuit designed to reduce short-duration interference pulses such as ignition or electrical switching noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise Figure<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measurement of the amount of noise added by an electronic circuit or receiver. Lower values generally indicate better weak-signal performance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise Floor<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The background noise level present in a receiver or radio system when no desired signal is being received.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise Floor Rise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An increase in the receiver background noise level caused by interference or changing environmental conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise Reduction<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal processing designed to reduce unwanted noise while retaining as much of the desired signal as possible.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Noise-Limited<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where reception quality is primarily limited by background noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Notch Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter designed to strongly attenuate a narrow range of frequencies while allowing frequencies outside that range to pass.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Null<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A direction or frequency at which the response of an antenna, filter or receiver becomes particularly weak.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Occupied Bandwidth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency range containing most of the power of a transmitted signal according to a specified measurement criterion.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">OCXO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Oven Controlled Crystal Oscillator \u2013 a crystal oscillator maintained at a controlled temperature for very high frequency stability.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">OFDM<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Orthogonal Frequency Division Multiplexing \u2013 a digital transmission technique that divides information among many closely spaced orthogonal subcarriers.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Offset Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency difference between transmit and receive frequencies in a duplex radio system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Omnidirectional<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Describes an antenna or radiation pattern providing approximately equal coverage in all horizontal directions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">One-Way Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A propagation path in which a signal can be received in one direction more effectively than the reverse direction.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Open Carrier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmitter operating with its carrier present without necessarily carrying useful audio or information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Operating Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency at which a transmitter, receiver or transceiver is intended to operate.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Overload<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition in which a signal is too strong for a receiver or circuit to handle correctly, potentially causing distortion or unwanted responses.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Overmodulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where modulation exceeds the permitted or intended limits of a transmission system, potentially producing distortion and splatter.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Packet<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A formatted block of digital data transmitted as a unit.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Packet Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A digital radio communication system in which information is divided into packets for transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Pan-Pan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An internationally recognised urgency call indicating a serious situation requiring assistance but not constituting immediate grave danger.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Panadapter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A display showing RF activity across a range of frequencies around the tuned frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Passband<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of frequencies that a filter or receiver allows to pass with relatively little attenuation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Path Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The reduction in radio signal power as a signal travels from transmitter to receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Path Profile<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A representation of terrain and other obstacles along a radio communication path.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Payload<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The useful information carried within a digital data packet, excluding protocol information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Peak Deviation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The maximum frequency deviation from the centre frequency of an FM signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Phase Noise<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted short-term fluctuations in the phase of an oscillator signal that can degrade receiver or transmitter performance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Phase Noise Floor<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The level of unwanted oscillator phase noise surrounding a carrier signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Pi Network<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A matching or filtering circuit using three reactive components arranged in a pi configuration.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Pilot Tone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reference tone transmitted by some radio systems to allow the receiver to identify or recover additional information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PLB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Personal Locator Beacon \u2013 a personal emergency beacon transmitting a distress signal to appropriate rescue systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PLL<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Phase-Locked Loop \u2013 an electronic circuit that locks the phase and frequency of an oscillator to a reference signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PLL Synthesizer<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A frequency synthesizer using a phase-locked loop to generate stable selectable frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PMR446<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A European licence-exempt personal mobile radio service using designated UHF frequencies for short-range communication.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Point-to-Point<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio communication link established between two specific locations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Polarisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The orientation of the electric field of an electromagnetic wave.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Polarisation Diversity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A diversity technique using antennas with different polarisation orientations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Portable Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station designed to be operated temporarily away from its normal fixed location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Pre-emphasis<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmitter process that increases higher audio frequencies before FM transmission to improve the signal-to-noise ratio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Pre-sets<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Stored frequencies or stations that can be quickly selected by the user.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Preamp<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A preamplifier used to increase the level of a weak signal before further processing.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Preselector<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A filter placed before the main receiver circuitry to reduce unwanted signals and improve resistance to overload.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Priority Channel<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A channel given special treatment by a scanning receiver and checked periodically while other channels are scanned.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Priority Scan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scanning function that periodically checks a designated priority channel while scanning other channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Product Detector<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A detector that mixes a received signal with a local oscillator signal to recover information from SSB or CW transmissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Programme Service<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The audio programme or radio service transmitted by a broadcaster.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The way radio waves travel from a transmitting antenna to a receiving location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation Forecast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A prediction of expected radio propagation conditions for particular frequencies, locations and times.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation Opening<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period when radio propagation conditions allow signals to be received over a path that is not normally available.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation Path<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The route taken by a radio signal between its transmitting and receiving locations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PSK<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Phase Shift Keying \u2013 a digital modulation method in which information is represented by controlled changes in carrier phase.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PTT<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Push-To-Talk \u2013 a control used to switch a radio from receive to transmit.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">PTT Lockout<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function preventing the push-to-talk control from activating the transmitter under specified conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QPSK<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Quadrature Phase Shift Keying \u2013 a digital modulation scheme using four carrier phase states to represent digital symbols.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QRM<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio shorthand for interference from other radio stations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QRN<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio shorthand for natural or electrical radio noise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QRP<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio terminology generally referring to low-power operation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio shorthand for fading or variation in signal strength.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSL<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A confirmation that a radio contact or reception has taken place.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSL Bureau<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A service that forwards QSL cards between radio operators.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSL Card<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A physical or electronic card or message confirming a radio contact or reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSL Manager<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A person or organisation responsible for handling QSL confirmations for a station or operator.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSL Report<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A report confirming reception or a radio contact, commonly including frequency, time, date and signal information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QSY<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio shorthand meaning to change frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">QTH<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Amateur radio shorthand for the location of a radio station or operator.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Quarter-Wave Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna approximately one quarter of a wavelength long, commonly used as a vertical antenna with a suitable ground or counterpoise.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radial<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A conductive element extending from an antenna base and forming part of the antenna ground or counterpoise system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radiated Power<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The radio-frequency power actually radiated by an antenna system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radiation Pattern<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A graphical or descriptive representation of the relative strength of an antenna in different directions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Amateur<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A person authorised to operate an amateur radio station under the applicable regulations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Beacon<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmitter sending a known identifying signal that can be used for navigation, identification or propagation monitoring.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Gateway<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Equipment that connects a radio system to another communications network or service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Horizon<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The approximate maximum distance for direct radio communication caused by the curvature of the Earth and atmospheric refraction.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Link<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A communication path between two or more locations using radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of listening to or observing radio-frequency transmissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Observatory<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A location equipped for systematic observation and measurement of radio signals or propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Regulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Rules governing the use of radio frequencies, transmitters, power levels and emissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Relay<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A system in which a radio signal is received and retransmitted to extend coverage.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Scanner<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver capable of automatically scanning multiple programmed frequencies or channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Silence<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period during which radio transmissions are intentionally prohibited or avoided.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Spectrum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The portion of the electromagnetic spectrum used for radio-frequency communications and related applications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Wave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An electromagnetic wave used to transmit energy and information through space or other propagation environments.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Random Wire<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A wire antenna of arbitrary length used for radio reception or transmission, normally with suitable matching when required.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Data System \u2013 a system used mainly on FM broadcasts to transmit station identification, programme information, traffic information and other data.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS AF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Alternative Frequencies information in RDS, allowing receivers to identify other frequencies carrying the same programme.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS PI Code<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Programme Identification code used by RDS to identify a particular radio programme or service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS PS<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Programme Service information in RDS, allowing compatible receivers to display a station or programme name.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS PTY<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Programme Type information in RDS identifying the general type of programme being broadcast.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS TA<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Traffic Announcement indicator in RDS, identifying when traffic information is being broadcast.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RDS TP<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Traffic Programme indicator in RDS, identifying stations that regularly carry traffic announcements.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receive Indicator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A visual or audible indication that a radio is receiving a signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receive Mode<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The modulation or demodulation mode selected by a receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio device designed to receive, select, amplify and demodulate radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Bandwidth<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of frequencies allowed through a receiver around its tuned frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Desense<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reduction in receiver sensitivity caused by a strong nearby transmission or other interfering signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Diversity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A technique using multiple receiving paths to improve reception during fading and multipath conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Front End<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The portion of a receiver containing the initial RF filtering, amplification and mixing circuitry.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Overload<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where excessive RF input causes a receiver to behave non-linearly or produce unwanted responses.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Sensitivity Threshold<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The minimum signal level at which a receiver provides a specified quality of reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Receiver Site<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The location where radio receiving equipment and antennas are installed.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reception Report<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A report sent to a broadcaster or station describing when and how well its transmission was received.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reciprocal Mixing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted mixing between a strong signal and phase noise from a receiver oscillator, potentially degrading reception of weak signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reciprocity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The general principle that, under equivalent conditions, a radio propagation path behaves similarly in both directions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reference Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A stable frequency used as a standard from which other frequencies are generated or measured.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reflected Power<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency power travelling back toward a transmitter because of an impedance mismatch.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reflected Wave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-frequency energy travelling back toward its source after reflection from an impedance mismatch.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reflection Coefficient<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measure of the proportion and phase of a wave reflected from a load because of impedance mismatch.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Relay<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station or system that receives a signal and retransmits it to another location or network.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Remote Control<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A method of controlling a radio receiver, transmitter or repeater from another location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Remote Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of monitoring a radio system or receiver from another location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Remote Receiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver located away from the operator and controlled or monitored remotely.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station that receives a signal and retransmits it, usually on another frequency, to extend communication range.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Controller<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Equipment controlling repeater functions such as identification, timers, tones and transmit switching.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Courtesy Tone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A tone transmitted by a repeater after a transmission to indicate that the channel is available.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Coverage<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The geographical area in which a repeater can reliably receive or transmit signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater ID<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An identification transmitted by a repeater to identify the repeater station.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Input<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency on which a repeater receives transmissions from users.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Link<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A communication connection between repeaters or between a repeater and another radio network.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Linking<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Connecting two or more repeaters so transmissions received by one can be retransmitted by another.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Offset<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency difference between a repeater input and output frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Output<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency on which a repeater retransmits signals to users.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Repeater Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A station that receives and retransmits radio signals to extend communication coverage.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Return Loss<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measurement of reflected RF power caused by impedance mismatch. Higher return loss generally indicates a better match.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Frequency \u2013 electromagnetic frequencies used for radio transmission and reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Amplifier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An amplifier designed to increase the strength of radio-frequency signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Choke<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A component designed to impede unwanted radio-frequency currents.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Front End<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The input section of a receiver that handles incoming radio-frequency signals before further processing.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Gain<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver control that adjusts the amplification applied to incoming radio-frequency signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Gain Control<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A control that allows the operator to vary receiver radio-frequency gain, useful for optimising weak-signal reception or reducing overload.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Shield<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A conductive enclosure or barrier designed to reduce unwanted radio-frequency coupling.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RF Spectrum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The distribution of radio-frequency energy across a range of frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RFI<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio Frequency Interference \u2013 unwanted RF energy that interferes with radio reception or operation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Roger Beep<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A tone transmitted at the end of a transmission, commonly associated with some CB radios.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Rotary Encoder<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An electronic rotary control commonly used as a tuning knob on modern radios.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RSSI<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Received Signal Strength Indicator \u2013 a measurement or indication of received radio signal strength.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">RX<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Common abbreviation for receive or receiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">S-Meter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver meter or display indicating the approximate strength of a received signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Satellite Communication<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio communication using artificial satellites to relay signals between locations.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SAW Filter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Surface Acoustic Wave filter \u2013 a filter using acoustic waves travelling across a specially designed surface to provide precise frequency filtering.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Scan List<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A programmed list of frequencies or channels that a scanner checks automatically.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Scanner Lockout<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scanner function that excludes a selected frequency or channel from scanning.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Scanning<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver function that automatically checks a series of frequencies or channels and stops when activity is detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Scatter Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation in which radio signals are scattered by atmospheric or other irregularities.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SDR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Software Defined Radio \u2013 a radio system in which functions traditionally implemented using dedicated analogue circuits are performed largely using digital processing and software.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SDR Dongle<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A small USB-connected software-defined radio receiver used with a computer or other host device.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SDR Receiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A software-defined radio receiver using digital processing and software to receive and process radio signals.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Search Scan<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function that searches a specified frequency range and pauses when an active signal is detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selcall<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selective Calling \u2013 a signalling system used to call a particular station or group using encoded information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selective Calling<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A system allowing a receiver to respond only when a particular tone, code or address is detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selectivity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a receiver to receive a desired signal while rejecting unwanted signals on nearby frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selectivity Curve<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A representation of receiver response showing how signals at different frequencies are attenuated around the tuned frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Selectivity Skirt<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The region outside a receiver passband where unwanted signals become increasingly attenuated.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sensitivity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of a receiver to detect weak signals. Receiver sensitivity may be specified in microvolts, dBm, dB\u00b5V or by measurements such as SINAD.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shadowing<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Reduction in radio signal strength caused by terrain, buildings or other obstacles.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SHF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Super High Frequency \u2013 radio frequencies from 3 GHz to 30 GHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shielding<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The use of conductive or magnetic material to reduce unwanted electromagnetic coupling.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Short Path<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The shorter great-circle route between two locations when discussing long-distance radio propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shortwave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A commonly used name for radio frequencies in the HF range from 3 MHz to 30 MHz. Shortwave signals can travel very long distances through ionospheric propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shortwave Broadcast<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio broadcast transmitted in the HF range and often intended for reception over very long distances.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shortwave Listener<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A person who listens to shortwave radio transmissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Side Lobe<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A secondary region of radiation or reception outside the main lobe of a directional antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sideband<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A band of frequencies produced on either side of a carrier when it is modulated.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal Detect<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A function that identifies when a radio-frequency signal exceeds a specified threshold.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal Report<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Information describing the strength and quality of a received radio signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal Strength<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measure of the strength of a received radio signal at a particular location.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal Trace<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A displayed or recorded representation of signal strength or frequency over time.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal-to-Noise Ratio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ratio between the strength of a desired signal and the level of unwanted noise, normally expressed in decibels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Simplex<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A communication method in which stations transmit and receive on the same frequency, with only one station transmitting at a time.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Simplex Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A frequency used for direct communication without separate repeater input and output frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SINAD<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Signal-to-Noise and Distortion ratio \u2013 a measurement commonly used to assess analogue receiver performance.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SINPO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reception-report system describing Signal strength, Interference, Noise, Propagation and Overall reception quality.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SIO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A reception-report system describing Signal strength, Interference and Overall quality.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Skip<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A term describing long-distance propagation where a signal leaves the local area and returns to Earth after ionospheric propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Skip Distance<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The approximate distance from a transmitter at which an ionospherically propagated signal first returns to Earth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Skip Zone<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An area between the limit of ground-wave reception and the point where skywave signals return to Earth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Skywave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio propagation in which signals travel through the ionosphere and return to Earth, enabling long-distance communication.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Smith Chart<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A graphical tool used to analyse impedance, transmission lines and RF matching networks.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Cycle<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The approximately 11-year cycle of changing solar activity that influences ionospheric conditions and HF propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Disturbance<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A solar event or condition capable of changing ionospheric and radio propagation conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Flare<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A sudden eruption of energy from the Sun that can alter ionospheric conditions and sometimes disrupt HF communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Flux<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measurement of solar radio emission used as an indicator of solar activity and HF propagation conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Maximum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period near the peak of the solar cycle when solar activity and sunspot numbers are relatively high.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Minimum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period near the low point of the solar cycle when solar activity and sunspot numbers are relatively low.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Solar Wind<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A stream of charged particles flowing outward from the Sun. Variations can affect Earth's ionosphere and magnetic environment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Space Diversity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A diversity technique using physically separated antennas so that they experience different fading conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Speaker<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An electroacoustic device that converts an electrical audio signal into audible sound.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spectrum<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of radio frequencies available for or used by radio services.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spectrum Analyser<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An instrument that displays signal strength across a range of frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spectrum Display<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A visual representation of radio-frequency activity across a range of frequencies.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spectrum Management<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The planning and regulation of radio-frequency spectrum use to minimise interference and improve efficient use.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Splatter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unwanted transmitter energy appearing outside the intended bandwidth, often caused by excessive modulation or poor transmitter adjustment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sporadic E<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A temporary region of intense ionisation in the E layer that can enable unusually long-distance VHF reception.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sporadic-E Opening<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A period when enhanced sporadic-E ionisation permits unusual long-distance VHF propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spurious Emission<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted RF emission occurring outside the intended transmission frequency or bandwidth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Spurious Response<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An unwanted receiver response to a signal at a frequency other than the desired tuned frequency.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Squelch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver function that mutes audio when the received signal falls below a preset threshold.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Squelch Tail<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A brief burst of noise heard when receiver squelch closes after a transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Squelch Threshold<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The signal level at which a squelch system opens or closes receiver audio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SSB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Single Sideband \u2013 a form of amplitude modulation in which one sideband is transmitted while the carrier is normally suppressed. It is widely used for HF voice communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Standing Wave<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A fixed pattern of voltage and current along a transmission line caused by the interaction of forward and reflected energy.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Station ID<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An abbreviation for station identification.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Station Identification<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmission used to identify a radio station, commonly using its name, call sign or other identifying information.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Station Log<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A record of radio stations received or contacted, commonly including frequency, date, time, mode and signal report.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Station Site<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The physical location where radio equipment and antennas are installed.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Stereo<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Audio reproduced using separate left and right channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Stereo Pilot<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The pilot signal transmitted as part of an FM stereo broadcast system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Stereo Separation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The ability of an FM stereo receiver to distinguish the left and right audio channels.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Stopband<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The range of frequencies that a filter is designed to attenuate significantly.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Subcarrier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A secondary carrier or frequency component used to transmit additional information within a larger signal.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sunspot<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A relatively dark region on the Sun associated with strong magnetic activity.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Sunspot Number<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A numerical measure of solar sunspot activity historically used as an indicator of solar activity and HF propagation conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Suppressed Carrier<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A carrier that has been greatly reduced or removed from a transmission to improve transmission efficiency, as used by many SSB systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SWL<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Shortwave Listening \u2013 the hobby of listening to shortwave broadcasts, utility stations and other HF transmissions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">SWR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Standing Wave Ratio \u2013 a measurement of the relationship between forward and reflected waves on a transmission line.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Symbol Rate<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The number of symbols transmitted per second in a digital communication system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Synchronous AM<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">AM reception using a locally generated carrier synchronised to the incoming carrier.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Synchronous Detection<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A detection technique using a locally generated carrier synchronised with the received signal, often improving AM reception during fading.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">T-Network<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An impedance matching network using three reactive components arranged in a T configuration.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Talkaround<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A mode allowing direct radio-to-radio communication without using a repeater.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Talkgroup<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A logical group of users within a trunked or digital radio system who share communications.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Talkgroup ID<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A numerical or digital identifier associated with a talkgroup in a digital or trunked radio system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">TCXO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Temperature Compensated Crystal Oscillator \u2013 a crystal oscillator designed to maintain improved frequency stability as temperature changes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Telemetry<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Automatic transmission of measurements or status information from remote equipment to a receiving station.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Telemetry Link<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio link used to transmit measurements or status information from remote equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Temperature Inversion<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An atmospheric condition in which temperature increases with altitude over a layer, potentially contributing to radio ducting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Test Transmission<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A transmission made to test equipment, coverage, signal quality or a new radio service.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Thermal Drift<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A change in frequency or electrical characteristics caused by temperature changes.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Third-Order Intercept<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A measurement associated with the linearity of an RF circuit and its resistance to third-order intermodulation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Time Signal<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmission providing an accurate reference for the current time.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Timebase<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A stable frequency or timing reference used by radio equipment or test instruments.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tone Squelch<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A squelch system that opens the receiver audio only when a specified tone or code is detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">TOT<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Time-Out Timer \u2013 a feature that automatically stops transmission after a preset period.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tower Frequency<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio frequency used for communication between aircraft and an airport control tower.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Traffic Announcement<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A broadcast announcement containing information about traffic conditions, delays, accidents or road conditions.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transceiver<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio device combining a transmitter and receiver in a single unit.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmission Line<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A cable or electrical path designed to carry radio-frequency energy between a transmitter or receiver and an antenna.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmit Indicator<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A visual or audible indication that a radio is transmitting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmit Inhibit<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A feature or condition that prevents a radio from transmitting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmit Mode<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The modulation method selected by a transmitter or transceiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmit Power<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The radio-frequency power produced by a transmitter before losses in cables, connectors and other components.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmitter<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio device that generates and amplifies a radio-frequency signal and supplies it to an antenna for transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Transmitter Site<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The location where a radio transmitter and associated antenna equipment are installed.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Troposphere<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The lowest major layer of Earth's atmosphere. Conditions within it can affect radio propagation.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tropospheric Propagation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Propagation through the lower atmosphere that can allow VHF and UHF signals to travel unusually long distances.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Trunked Radio<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio communication system in which a pool of frequencies is dynamically assigned to users or groups.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tuning<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The process of adjusting a receiver to the frequency of a desired station or transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tuning Knob<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A physical control used to change the operating frequency of a receiver or transceiver.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Tuning Step<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The frequency increment by which a receiver or transceiver changes frequency when its tuning control is adjusted.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">TX<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Common abbreviation for transmit or transmitter.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">UHF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Ultra High Frequency \u2013 radio frequencies from 300 MHz to 3 GHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Under-Modulation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A condition where the modulation level is significantly below the intended operating level.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Unun<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An impedance-transforming device used between unbalanced radio-frequency circuits or antenna systems.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Uplink<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio transmission from a ground station or other lower location to a satellite or elevated communication system.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Urgency Signal<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio signal indicating a serious situation requiring assistance but not necessarily immediate distress response.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Usable Sensitivity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The minimum received signal level producing acceptable reception according to a defined criterion.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">USB<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Upper Sideband \u2013 the upper sideband component of an SSB transmission.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Utility Monitoring<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The practice of listening to non-broadcast services such as aviation, maritime, weather and other radio services.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Utility Station<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A radio station providing communications or information services other than conventional entertainment broadcasting.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Variable Bandwidth Tuning<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A receiver feature that allows the operator to continuously or incrementally adjust the receiver bandwidth.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Vertical Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">An antenna whose main radiating element is oriented vertically.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Vertical Polarisation<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Radio-wave polarisation in which the electric field is predominantly vertical.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VFO<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Variable Frequency Oscillator \u2013 a frequency source whose operating frequency can be varied for tuning a radio.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VHF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Very High Frequency \u2013 radio frequencies from 30 MHz to 300 MHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VLF<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Very Low Frequency \u2013 radio frequencies from 3 kHz to 30 kHz.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VOLMET<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Aviation radio broadcasts providing meteorological information for aircraft in flight.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VOR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VHF Omnidirectional Range \u2013 an aviation radio navigation system allowing aircraft to determine bearing from a ground station.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VOX<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Voice Operated Transmit \u2013 a system that automatically switches a transmitter on when speech or another audio signal is detected.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VOX Delay<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The time a transmitter remains active after detected speech has stopped.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VOX Sensitivity<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A control determining how much audio is required to activate VOX.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">VSWR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Voltage Standing Wave Ratio \u2013 another name for SWR.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Warm-Up Drift<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Frequency change occurring while radio equipment warms to its normal operating temperature.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Waterfall<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A scrolling graphical representation of radio-frequency activity over time.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Waterfall Display<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A graphical display commonly used with SDR software showing radio activity over time, with frequency represented horizontally.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Waterfall History<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The accumulated historical display of RF activity in a waterfall spectrum display.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Wavelength<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">The distance between corresponding points on successive cycles of a radio wave. For a wave travelling at a given speed, wavelength decreases as frequency increases.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">WebSDR<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A remotely accessible software-defined radio receiver that allows users to listen to radio signals through a web interface.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Whine<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A high-pitched unwanted audio or RF interference often associated with switching power supplies or digital electronics.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Whip Antenna<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A simple vertical antenna consisting of a flexible or rigid metal rod, commonly used on portable radios and mobile equipment.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">World Band<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Another name commonly used for the HF or shortwave range, particularly on consumer multiband receivers.<\/div><\/td><\/tr><tr><td data-mtr-content=\"term\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">Yagi<\/div><\/td><td data-mtr-content=\"meaning\" class=\"mtr-td-tag\"><div class=\"mtr-cell-content\">A directional antenna consisting of a driven element and one or more parasitic elements.<\/div><\/td><\/tr><\/tbody><\/table><\/div>\n<hr>\n<p style=\"text-align: center;\"><a href=\"..\/..\/..\/\">Home<\/a> | <a href=\"..\/..\/\">Tables<\/a> | <a href=\"..\/\">Radio Frequencies<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>This is a brief list of some commonly used terms and expressions used by radio enthusiasts and resellers. It is not an exhaustive list and many of the terms can be found in greater detail in the Wikipedia. http:\/\/www.wikipedia.org You can use your browser\u2019s Find on Page feature to search for a term on the&#8230;<\/p>\n","protected":false},"author":1,"featured_media":9617,"parent":590,"menu_order":2,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ngg_post_thumbnail":0,"_kad_post_transparent":"default","_kad_post_title":"default","_kad_post_layout":"default","_kad_post_sidebar_id":"","_kad_post_content_style":"default","_kad_post_vertical_padding":"default","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"class_list":["post-158","page","type-page","status-publish","has-post-thumbnail","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Commonly used radio terminology - GarfNet<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/garfnet.org.uk\/cms\/tables\/radio-frequencies\/commonly-used-radio-terminology\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Commonly used radio terminology - GarfNet\" \/>\n<meta property=\"og:description\" content=\"This is a brief list of some commonly used terms and expressions used by radio enthusiasts and resellers. 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