Amateur radio glossary

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The purpose of this glossary is to combine all other amateur radio glossaries to simplify lookup



  • definitions marked as (FCC a#) come from (97.3(a)) (terms), and similarly b (technical symbols) or c (emission types); items marked with a * as (FCC a1*) have been abridged for brevity.
  • jargon from various sources
  • (XX) source needs citation
  • (wp) Wikipedia is a detailed source of extended information about many of these terms.
  • (basics explained and glossary)



(wp) Amplitude Modulation; a modulation method that varies output amplitude with input amplitude; used on HF mostly; typically 6khz in amateur bands; sometimes called "double sideband" as it contains both the LSB and USB signals (and possibly the carrier too)
Amateur operator
(FCC a1) A person named in an amateur operator/primary license station grant on the ULS consolidated licensee database to be the control operator of an amateur station.
Amateur radio services
(FCC a2) The amateur service, the amateur-satellite service and the radio amateur civil emergency service.
Amateur service
(FCC a4) A radio communication service for the purpose of self training, intercommunication and technical investigations carried out by amateurs, that is, duly authorized persons interested in radio technique solely with a personal aim and without pecuniary interest.
Amateur station
A station in an amateur radio service consisting of the apparatus necessary for carrying on radio communications.
(wp) a digital protocol that uses packet radio to transmit telemetry, including instant messaging, GPS location data, weather data, and more
Automatic control
(FCC a6) The use of devices and procedures for control of a station when it is transmitting so that compliance with the FCC Rules is achieved without the control operator being present at a control point.
Auxiliary station
(FCC a7) An amateur station, other than in a message forwarding system, that is transmitting communications point-to-point within a system of cooperating amateur stations.
(FCC a8) The width of a frequency band outside of which the mean power of the transmitted signal is attenuated at least 26 dB below the mean power of the transmitted signal within the band. (XX) Bandwidth may also be applied to a digital data stream, in which case it is measured in units of symbols (frequently bits) per second.
Band plan 
(XX) legal limits and gentleman's agreements for mapping use of parts of a frequency spectrum in content, modulation modes, and powers
(FCC a9) An amateur station transmitting communications for the purposes of observation of propagation and reception or other related experimental activities. (XX) Beacons typically transmit a periodic signal with an unchanging identification message and possibly some simple telemetry.
(FCC a10) Transmissions intended for reception by the general public, either direct or relayed. (XX) Broadcasting is not allowed in amateur radio (except in emergency conditions); amateur signals are intended for other amateurs or specific allowed third parties
Call sign system
(FCC a11*) The method used to select a call sign for amateur station over-the-air identification purposes. The call sign systems are: Sequential, Vanity, Special event
CEPT radio amateur license
(FCC a12) A license issued by a country belonging to the European Conference of Postal and Telecommunications Administrations (CEPT) that has adopted Recommendation T/R 61-01 (Nice 1985, Paris 1992, Nicosia 2003).
Control operator
(FCC a13) An amateur operator designated by the licensee of a station to be responsible for the transmissions from that station to assure compliance with the FCC Rules.
Control point
(FCC a14) The location at which the control operator function is performed.
(FCC A15) Certificate of successful completion of an examination.
(FCC C1, XX) Continuous Wave; A modulation of a type of information content: International Morse code telegraphy emissions having designators with A, C, H, J or R as the first symbol; 1 as the second symbol; A or B as the third symbol; and emissions J2A and J2B.; morse code modules letters and numbers by transmitting a constant tone that is interrupted in intervals to create symbols; morse code is the only digital mode designed to be encoded and decoded by humans without computers; typically 150hz max bandwidth
(FCC c2) A type of information content: Telemetry, telecommand and computer communications emissions having (i) designators with A, C, D, F, G, H, J or R as the first symbol, 1 as the second symbol, and D as the third symbol; (ii) emission J2D; and (iii) emissions A1C, F1C, F2C, J2C, and J3C having an occupied bandwidth of 500 Hz or less when transmitted on an amateur service frequency below 30 MHz. Only a digital code of a type specifically authorized in this part may be transmitted.
Earth station
(FCC a16) An amateur station located on, or within 50 km of the Earth's surface intended for communications with space stations or with other Earth stations by means of one or more other objects in space.
EHF (extremely high frequency)
(FCC b1) The frequency range 30-300 GHz.
EME (Earth Moon Earth)
(XX) Communicating by bouncing signals off the moon; requires equipment with low noise floor, very high gain antennas, and typically high output power, although modern SDR can use DSP to succeed with just low noise floor and high gain
External RF Power Amplifier
(FCC a18) A device capable of increasing power output when used in conjunction with, but not an integral part of, a transmitter.
(FCC A20) Federal Aviation Administration.
Fast scan TV
Image modulation; typically uses 6mhz wide NTSC encoding (60 half frames a second) in the UHF band and can be demodulated with a regular analog TV (corresponds with cable channel 57-61)
(FCC A21) Federal Communications Commission.
Frequency coordinator
(FCC a22) An entity, recognized in a local or regional area by amateur operators whose stations are eligible to be auxiliary or repeater stations, that recommends transmit/receive channels and associated operating and technical parameters for such stations in order to avoid or minimize potential interference.
Frequency shift keying (FSK) 
a digital modulation mode that forms digital symbols by alternating between frequencies; for example, RTTY
Field strength 
(XX) density of a magnetic or radio frequency spectrum through a cross sectional area
(wp) Frequency Modulation; a modulation method where output frequency varies with input amplitude; generally used on vhf and higher, especially with repeaters; can be 5khz, 15khz (vhf) , 25khz (uhf), 100khz (commercial, not amateur)


Harmful interference
(FCC a23) Interference which endangers the functioning of a radio navigation service or of other safety services or seriously degrades, obstructs or repeatedly interrupts a radio communication service operating in accordance with the Radio Regulations.
HF (high frequency)
(FCC b2) The frequency range 3-30 MHz.
(FCC b3) Hertz.
(FCC A24) International Amateur Radio Permit. A document issued pursuant to the terms of the Inter-American Convention on an International Amateur Radio Permit by a country signatory to that Convention, other than the United States. Montrouis, Haiti.
(FCC c3) A type of information content: Facsimile and television emissions having designators with A, C, D, F, G, H, J or R as the first symbol; 1, 2 or 3 as the second symbol; C or F as the third symbol; and emissions having B as the first symbol; 7, 8 or 9 as the second symbol; W as the third symbol.
(FCC a25) Words, letters or numerals appended to and separated from the call sign during the station identification.
Information bulletin
(FCC a26) A message directed only to amateur operators consisting solely of subject matter of direct interest to the amateur service.
International Morse code
(FCC a27) A dot-dash code as defined in ITU-T Recommendation F.1 (March, 1998), Division B, I. Morse code. Frequently modulated as CW
(FCC A28) International Telecommunication Union.
Line A
(FCC a29) Begins at Aberdeen, WA, running by great circle arc to the intersection of 48° N, 120° W, thence along parallel 48° N, to the intersection of 95° W, thence by great circle arc through the southernmost point of Duluth, MN, thence by great circle arc to 45° N, 85° W, thence southward along meridian 85° W, to its intersection with parallel 41° N, thence along parallel 41° N, to its intersection with meridian 82° W, thence by great circle arc through the southernmost point of Bangor, ME, thence by great circle arc through the southernmost point of Searsport, ME, at which point it terminates.
Local control
(FCC a30) The use of a control operator who directly manipulates the operating adjustments in the station to achieve compliance with the FCC Rules.
(FCC b4) Meters.
(FCC C4) Tone-modulated international Morse code telegraphy emissions having designators with A, C, D, F, G, H or R as the first symbol; 2 as the second symbol; A or B as the third symbol.
Message forwarding system
(FCC a31) A group of amateur stations participating in a voluntary, cooperative, interactive arrangement where communications are sent from the control operator of an originating station to the control operator of one or more destination stations by one or more forwarding stations.
MF (medium frequency)
(FCC b5) The frequency range 300-3000 kHz.
(XX) maximum permissible exposure


National Radio Quiet Zone
(FCC a32) The area in Maryland, Virginia and West Virginia bounded by 39° 15' N on the north, 78° 30' W on the east, 37° 30' N on the south and 80° 30' W on the west. (wp) This area is home of a number of high sensitivity radio telescopes and equipment run by NASA, NSA, and others. Part 97 mentions restrictions on amateur radio beacons in this area; transmissions of any kind near certain facilities must be coordinated with the area frequency coordinator.
Noise figure 
(wp) The ratio (in decibels) of noise added to a signal by a device to the noise that would be in the signal if none were added; especially applies to amplifiers.
Noise floor 
(wp) The average power of the sum noise from all noise sources. A weak signal must be above the noise floor to be discernible.
PEP (peak envelope power)
(FCC b6) The average power supplied to the antenna transmission line by a transmitter during one RF cycle at the crest of the modulation envelope taken under normal operating conditions.
packet radio
(wp) digital mode, usually FM modulated on VHF, uses a channel as wide as a voice channel
Phase shift keying 
a digital modulation method that forms symbols by adjusting phase of the carrier; for example, PSK31
(FCC c5) A type of information content: Speech and other sound emissions having designators with A, C, D, F, G, H, J or R as the first symbol; 1, 2 or 3 as the second symbol; E as the third symbol. Also speech emissions having B as the first symbol; 7, 8 or 9 as the second symbol; E as the third symbol. MCW for the purpose of performing the station identification procedure, or for providing telegraphy practice interspersed with speech. Incidental tones for the purpose of selective calling or alerting or to control the level of a demodulated signal may also be considered phone.
(FCC a33) For the purposes of this Part, a person who is licensed to practice in a place where the amateur service is regulated by the FCC, as either a Doctor of Medicine (MD) or a Doctor of Osteopathy (DO).
Primary allocation 
(XX) attribute of a range of frequencies over which a radio user (amateur or otherwise) is the primary user; secondary users must not interfere with primary users and must accept interference from primary users
(PSK31) a digital mode using phase shift keying with varicode encoding to send ascii in a 31hz bandwidth; PSK31 was designed to have a symbol rate close to average typing speed
(FCC c6) Emissions having designators with K, L, M, P, Q, V or W as the first symbol; 0, 1, 2, 3, 7, 8, 9 or X as the second symbol; A, B, C, D, E, F, N, W or X as the third symbol.
Quad antenna 
(wp) a directional antenna that uses an array of loops (sometimes square) including a driven element, directors, and reflectors similar to a yagi.
Question pool
(FCC a34) All current examination questions for a designated written examination element.
Question set
(FCC a35) A series of examination questions on a given examination selected from the question pool.
Radio Regulations
(FCC a36) The latest ITU Radio Regulations to which the United States is a party.
RACES (radio amateur civil emergency service)
(FCC a37) A radio service using amateur stations for civil defense communications during periods of local, regional or national civil emergencies.
Remote control
(FCC a38) The use of a control operator who indirectly manipulates the operating adjustments in the station through a control link to achieve compliance with the FCC Rules.
(FCC a39) An amateur station that simultaneously retransmits the transmission of another amateur station on a different channel or channels.
(FCC B7) Radio frequency.
(wp; FCC c7) Radioteletype ; a digital mode using a pair of tones (frequency shift keying) to encode text; this mode was originally used with electromechanical teleprinters; Narrow-band direct-printing telegraphy emissions having designators with A, C, D, F, G, H, J or R as the first symbol; 1 as the second symbol; B as the third symbol; and emission J2B.
Secondary allocation 
(XX) attribute of a range of frequencies over which a radio user (amateur or otherwise) shares the band with users of a different license type; secondary users must not interfere with primary users and must accept interference from primary users


SHF (super-high frequency)
(FCC b8) The frequency range 3-30 GHz.
single side band (SSB USB LSB)
(wp) A modulation for phone mode for HF typically 3khz bandwidth; sometimes used on VHF/UHF for weak signal and long distance; SSB is similar to AM except only one side band is transmitted (upper or lower) and the carrier may be suppressed
Slow Scan TV (SSTV) 
(wp) a low bandwidth modulation method that transmits pictures digitally using the bandwidth of a SSB phone channel; typically uses SSB modulation with either a FAX mode or digitally transmitting a jpeg or other similar digital image format; typically one image per transmission, 1-5 minutes per image.
Space station
(FCC a40) An amateur station located more than 50 km above the Earth's surface.
Space telemetry
(FCC a41) A one-way transmission from a space station of measurements made from the measuring instruments in a spacecraft, including those relating to the functioning of the spacecraft.
Spurious emission
(FCC a42) An emission, on frequencies outside the necessary bandwidth of a transmission, the level of which may be reduced without affecting the information being transmitted.
(FCC c8) Spread Spectrum; A modulation mode that spreads emissions over a wide range with the advantage that it is naturally resistant to interference and jamming; emissions using bandwidth-expansion modulation emissions having designators with A, C, D, F, G, H, J or R as the first symbol; X as the second symbol; X as the third symbol.
(FCC a43) A one-way transmission to initiate, modify, or terminate functions of a device at a distance.
Telecommand station
(FCC a44) An amateur station that transmits communications to initiate, modify, or terminate functions of a space station.
(FCC a45) A one-way transmission of measurements at a distance from the measuring instrument.
(FCC c9) Emissions containing no information having the designators with N as the third symbol. Test does not include pulse emissions with no information or modulation unless pulse emissions are also authorized in the frequency band.
Third-party communications
(FCC a46) A message from the control operator (first party) of an amateur station to another amateur station control operator (second party) on behalf of another person (third party who might be unlicensed).
UHF (ultra-high frequency)
(FCC b9) The frequency range 300-3000 MHz.
ULS (Universal Licensing System)
(FCC a47) The consolidated database, application filing system and processing system for all Wireless Telecommunications Services.
upper side band; a type of single sideband
(FCC A48) Volunteer examiner.
(FCC A49) Volunteer-examiner coordinator.
VHF (very-high frequency)
(FCC b10) The frequency range 30-300 MHz.
(FCC b11) Watts.
(wp) a directional antenna that uses an array of dipole like elements including a driven element, reflectors, and directors.
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