The

International Telecommunication Union The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...

uses an internationally agreed system for classifying

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upp ...

signals. Each type of radio emission is classified according to its

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

, method of

modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...

, nature of the modulating signal, and type of information transmitted on the carrier signal. It is based on characteristics of the ''signal'', not on the transmitter used. An emission designation is of the form ''BBBB 123 45'', where ''BBBB'' is the bandwidth of the signal, ''1'' is a letter indicating the type of modulation used of the main carrier (not including any subcarriers which is why FM stereo is F8E and not D8E), ''2'' is a digit representing the type of modulating signal again of the main carrier, ''3'' is a letter corresponding to the type of information transmitted, ''4'' is a letter indicating the practical details of the transmitted information, and ''5'' is a letter that represents the method of

multiplexing In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - a ...

. The ''4'' and ''5'' fields are optional. This designation system was agreed at the 1979

World Administrative Radio Conference The World Administrative Radio Conference (WARC) was a technical conference of the International Telecommunication Union (ITU) where delegates from member nations of the ITU met to revise or amend the entire international radio regulations pertaini ...

(WARC 79), and gave rise to the Radio Regulations that came into force on 1 January 1982. A similar designation system had been in use under prior Radio Regulations.

Designation details

Bandwidth

The bandwidth (''BBBB'' above) is expressed as four characters: three digits and one letter. The letter occupies the position normally used for a decimal point, and indicates what unit of

frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...

is used to express the bandwidth. The letter ''H'' indicates

Hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...

, ''K'' indicates

kilo KILO (94.3 FM broadcasting, FM, 94.3 KILO) is a radio station broadcasting in Colorado Springs, Colorado, Colorado Springs and Pueblo, Colorado, Pueblo, Colorado. It also streams online. History KLST and KPIK-FM The 94.3 signal signed on th ...

Hertz, ''M'' indicates

mega Mega or MEGA may refer to: Science * mega-, a metric prefix denoting 106 * Mega (number), a certain very large integer in Steinhaus–Moser notation * "mega-" a prefix meaning "large" that is used in taxonomy * Gravity assist, for ''Moon-Eart ...

Hertz, and ''G'' indicates

giga Giga ( or ) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (109 or ). It has the symbol G. ''Giga'' is derived from the Greek word (''gígas''), meaning "giant". The ''Oxford English Dic ...

Hertz. For instance, "500H" means 500 Hz, and "2M50" means 2.5 MHz. The first character must be a digit between ''1'' and ''9'' or the letter ''H''; it may not be the digit ''0'' or any other letter.

Type of modulation

Type of modulating signal

Types 4 and 5 were removed from use with the 1982 Radio Regulations. In previous editions, they had indicated facsimile and video, respectively.

Type of transmitted information

Details of information

Multiplexing

Common examples

There is some overlap in signal types, so a transmission might legitimately be described by two or more designators. In such cases, there is usually a preferred conventional designator.

Broadcasting

;A3E or A3E G : Ordinary

amplitude modulation Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to ...

used for

low frequency Low frequency (LF) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, respectively, it is also known as the kilometre band or kilometre wave. LF radio waves exh ...

and

medium frequency Medium frequency (MF) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hect ...

AM broadcasting AM broadcasting is radio broadcasting using amplitude modulation (AM) transmissions. It was the first method developed for making audio radio transmissions, and is still used worldwide, primarily for medium wave (also known as "AM band") transmis ...

;A8E, A8E H: AM stereo broadcasting. ;F8E, F8E H :

FM broadcasting FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is cap ...

for radio transmissions on VHF, and as the audio component of

analogue television Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog s ...

transmissions. Since there are generally pilot tones (subcarriers) for stereo and RDS the designator '8' is used, to indicate multiple signals. ;C3F, C3F N : Analogue

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

, SÉCAM, or

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

television video signals (formerly type ''A5C'', until 1982) ;C7W :

ATSC Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...

digital television Digital television (DTV) is the transmission of television signals using digital encoding, in contrast to the earlier analog television technology which used analog signals. At the time of its development it was considered an innovative advanc ...

, commonly on VHF or UHF ;G7W :

DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...

ISDB-T Integrated Services Digital Broadcasting (ISDB; Japanese: , ''Tōgō dejitaru hōsō sābisu'') is a Japanese broadcasting standard for digital television (DTV) and digital radio. ISDB supersedes both the NTSC-J analog television system and th ...

, or

DTMB DTMB (Digital Terrestrial Multimedia Broadcast) is the digital TV standard for mobile and fixed devices, developed in the People's Republic of China. It is used there and in both of their special administrative regions (Hong Kong and Macau), and ...

, commonly on VHF or UHF

Two-way radio

;A3E : AM speech communication – used for aeronautical & amateur communications ;F3E : FM speech communication – often used for

marine radio Marine VHF radio is a worldwide system of two way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore (for example with harbormasters), and in certain circumstances ship-to-a ...

and many other VHF communications ;20K0 F3E : Wide FM, 20.0 kHz width, ±5

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...

deviation, still widely used for

Ham Radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

NOAA The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

weather radio A weather radio is a specialized radio receiver that is designed to receive a public broadcast service, typically from government-owned radio stations, dedicated to broadcasting weather forecasts and reports on a continual basis, with the routine we ...

, marine, and aviation users and land mobile users below 50 MHz ;11K2 F3E : Narrow FM, 11.25

bandwidth, ±2.5

deviation – In the United States, all Part 90

Land Mobile Radio Service Land mobile service (short: LMS) is – in line to ITU Radio Regulations – a mobile service between base stations and land mobile stations, or between land mobile stations. In accordance with ''ITU Radio Regulations'' (article 1) variations of ...

(LMRS) users operating above 50 MHz were required to upgrade to narrowband equipment by 1 January 2013. ;6K00 F3E : Even narrower FM, future roadmap for

(LMRS), already required on 700 MHz public safety band ;J3E : SSB speech communication, used on HF bands by marine, aeronautical and amateur users ;R3E : SSB with reduced carrier (

AME #REDIRECT AME {{redirect category shell, {{R from other capitalisation{{R from ambiguous page ...

) speech communication, primarily used on HF bands by the military (a.k.a. ''compatible'' sideband)

Low-speed data

;N0N : Continuous, unmodulated carrier, formerly common for

radio direction finding Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio station ...

(RDF) in marine and aeronautical navigation. ;A1A : Signalling by keying the carrier directly, a.k.a.

Continuous Wave A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. It may refer to e.g. a laser or particle ...

(CW) or On-Off Keying (OOK), currently used in

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

. This is often but not necessarily

Morse code Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of ...

. ;A2A : Signalling by transmitting a modulated tone with a carrier, so that it can easily be heard using an ordinary AM receiver. It was formerly widely used for station identification of

non-directional beacon A non-directional beacon (NDB) or non-directional radio beacon is a radio beacon which does not include directional information. Radio beacons are radio transmitters at a known location, used as an aviation or marine navigational aid. NDB are ...

s, usually but not exclusively

(an example of a

modulated continuous wave Modulated continuous wave (MCW) is Morse code telegraphy, transmitted using an audio tone to modulate a carrier wave. The Federal Communications Commission defines modulated continuous wave in 47 CFR §97.3(c)(4) as "Tone-modulated international ...

, as opposed to A1A, above). ;F1B :

Frequency-shift keying Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for communication systems such as telemetry, weather ball ...

(FSK) telegraphy, such as

RTTY Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. Radioteletype evolved from earlier landline teleprinter o ...

. ;F1C :

High frequency High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten ...

Radiofax Radiofacsimile, radiofax or HF fax is an analogue mode for transmitting monochrome images via high frequency (HF) radio waves. It was the predecessor to slow-scan television (SSTV). It was the primary method of sending photographs from remote s ...

;F2D : Data transmission by frequency modulation of a radio frequency carrier with an audio frequency FSK subcarrier. Often called AFSK/FM. ;J2B : Phase-shift keying such as

PSK31 PSK31 or " Phase Shift Keying, 31 Baud", also BPSK31 and QPSK31, is a popular computer-sound card-generated radioteletype mode, used primarily by amateur radio operators to conduct real-time keyboard-to-keyboard chat, most often using frequenci ...

(BPSK31)

Other

;P0N : Unmodulated

Pulse-Doppler radar A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars an ...

Notes

The emission designator for QAM is D7W. The D7W comes from Paragraph 42 of the FCC's July 10, 1996, Digital Declaratory Order allowing then ITFS/MMDS stations to use 64QAM digital instead of NTSC analog. The emission designator for COFDM is W7D. The W7D comes from Paragraph 40 of the November 13, 2002, ET Docket 01-75 R&O. It is only concidence that the QAM and COFDM emission designators are reciprocals.