The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, 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. The 4 and 5 fields are optional.

This designation system was agreed at the 1979 World Administrative Radio Conference (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 is used to express the bandwidth. The letter H indicates Hertz, K indicates kiloHertz, M indicates megaHertz, and G indicates gigaHertz. 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.[1]

Type of modulation

CharacterDescription
ADouble-sideband amplitude modulation (e.g. AM broadcast radio)
BIndependent sideband (two sidebands containing different signals)
CVestigial sideband (e.g. NTSC)
DCombination of AM and FM or PM
FFrequency modulation (e.g. FM broadcast radio)
GPhase modulation
HSingle-sideband modulation with full carrier (e.g. as used by CHU)
JSingle-sideband with suppressed carrier (e.g. Shortwave utility and amateur stations)
KPulse-amplitude modulation
LPulse-width modulation (e.g. as used by WWVB)
MPulse-position modulation
NUnmodulated carrier (steady, single-frequency signal)
PSequence of pulses without modulation
QSequence of pulses, with phase or frequency modulation in each pulse
RSingle-sideband with reduced or variable carrier
VCombination of pulse modulation methods
WCombination of any of the above
XNone of the above

Type of modulating signal

CharacterDescription
0No modulating signal
1One channel containing digital information, no subcarrier
2One channel containing digital information, using a subcarrier
3One channel containing analog information
7More than one channel containing digital information
8More than one channel containing analog information
9Combination of analog and digital channels
XNone of the above

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

CharacterDescription
AAural telegraphy, intended to be decoded by ear, such as Morse code
BElectronic telegraphy, intended to be decoded by machine (radioteletype and digital modes)
CFacsimile (still images)
DData transmission, telemetry or telecommand (remote control)
ETelephony (voice or music intended to be listened to by a human)
FVideo (television signals)
NNo transmitted information (other than existence of the signal)
WCombination of any of the above
XNone of the above

Details of information

CharacterDescription
ATwo-condition code, elements vary in quantity and duration
BTwo-condition code, elements fixed in quantity and duration
CTwo-condition code, elements fixed in quantity and duration, error-correction included
DFour-condition code, one condition per "signal element"
EMulti-condition code, one condition per "signal element"
FMulti-condition code, one character represented by one or more conditions
GMonophonic broadcast-quality sound
HStereophonic or quadraphonic broadcast-quality sound
JCommercial-quality sound (non-broadcast)
KCommercial-quality sound—frequency inversion and-or "band-splitting" employed
LCommercial-quality sound, independent FM signals, such as pilot tones, used to control the demodulated signal
MGreyscale images or video
NFull-color images or video
WCombination of two or more of the above
XNone of the above

Multiplexing

CharacterDescription
CCode-division (excluding spread spectrum)
FFrequency-division
NNone used / not multiplexed
TTime-division
WCombination of Frequency-division and Time-division
XNone of the above

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 used for low frequency and medium frequency AM broadcasting
A8E, A8E H
AM stereo broadcasting.
F8E, F8E H
FM broadcasting for radio transmissions on VHF, and as the audio component of analogue television 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, SÉCAM, or NTSC television video signals (formerly type A5C, until 1982)
C7W
ATSC digital television, commonly on VHF or UHF
G7W
DVB-T, ISDB-T, or DTMB digital television, 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 and many other VHF communications
20K0 F3E
Wide FM, 20.0 kHz width, ±5 kHz deviation, still widely used for amateur radio, NOAA weather radio, marine, and aviation users and land mobile users below 50 MHz[2]
11K2 F3E
Narrow FM, 11.25 kHz bandwidth, ±2.5 kHz deviation In the United States, all Part 90 Land Mobile Radio Service (LMRS) users operating above 50 MHz were required to upgrade to narrowband equipment by 1 January 2013.[3][4][5]
6K00 F3E
Even narrower FM, future roadmap for Land Mobile Radio Service (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) 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 (RDF) in marine and aeronautical navigation.
A1A
Signalling by keying the carrier directly, a.k.a. continuous wave (CW) or on–off keying, currently used in amateur radio. This is often but not necessarily Morse code.
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 beacons, usually but not exclusively Morse code (an example of a modulated continuous wave, as opposed to A1A, above).
F1B
Frequency-shift keying (FSK) telegraphy, such as RTTY.[lower-alpha 1]
F1C
High frequency Radiofax
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 (BPSK31)

Other

P0N
Unmodulated Pulse-Doppler radar

Notes

  1. The designators F1B and F1D should be used for FSK radiotelegraphy and data transmissions, no matter how the radio frequency signal is generated (common examples are Audio FSK used to modulate an SSB transmitter or direct FSK modulation of an FM transmitter via varactor diode). However, occasionally the alternatives J2B and J2D are used to designate FSK signals generated by audio modulation of an SSB transmitter.

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 coincidence that the QAM and COFDM emission designators are reciprocals.

References

  1. "TRC-43 — Designation of Emissions, Class of Station and Nature of Service". Industry Canada.
  2. "NOAA weather radio" (PDF). National Oceanographic and Atmospheric Administration. Archived from the original (PDF) on 2013-10-08. Retrieved 2014-04-23.
  3. "Narrowbanding for technicians" (PDF). adcommeng.com.
  4. "Narrowbanding transition". Public safety spectrum. Federal Communications Commission.
  5. "Committee Report" (PDF). American Radio Relay League. July 2010.

Further reading

  • "Complete List of Radio Regulations". Retrieved 2011-12-17.
  • Radio Regulations, ITU, Geneva, 1982
  • Radio Regulations, 2004, ITU Geneva, 2004, c.f. Volume 2 - Appendices, Appendix 1
  • Radiocommunications Vocabulary, Recommendation ITU-R V.573-4, ITU-R, Geneva, 2000
  • Determination of Necessary Bandwidths Including Examples for their Calculation, Recommendation ITU-R SM.1138, Geneva, 1995
  • Emission characteristics of radio transmissions, Australian Communications Authority, Canberra
  • Notes Regarding Designation of Emission, Industry Canada, 1982
  • Eckersley, R.J. Amateur Radio Operating Manual, 3rd edition, Radio Society of Great Britain, 1985, ISBN 0-900612-69-X
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