Emission Classification

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What are they?

Emission classification coding is designed to provide an internationally recognised way of describing the essential characteristics of a radio frequency transmission

How are they written?

Emission codes are usually written in the form XXXX 12345, where;

  • XXXX is used to describe the bandwidth. For example 750H means 750 Hz, and 2K50 means 2.5KHz
  • 12345 is used to describe the other 5 characteristics listed below. Note that characteristics 4 and 5 are optional and are frequently missing from emission codes.
  • 1 Modulation of the main carrier
  • 2 The nature of the signals modulating the main carrier
  • 3 The type of information being transmitted
  • 4 Details of signals
  • 5 Nature of multiplexing


Carrier modulation

NUnmodulated carrier
ADouble-sideband amplitude modulation
HSingle-sideband with full carrier
RSingle-sideband with reduced-carrier or variable carrier
JSingle-sideband with suppressed carrier
BIndependent sideband (two sidebands containing different signals)
CVestigial sideband e.g. NTSC
FFrequency modulation
GPhase modulation
DCombination of AM and FM or PM
PSequence of pulses without modulation
KPulse amplitude modulation
LPulse width modulation
MPulse position modulation
QSequence of pulses, phase or frequency modulation within each pulse
VCombination of pulse modulation methods
WCombination of any of the above
XNone of the above

Nature of modulating signals

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

Type of information being transmitted

NNo transmitted information
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
DTelemetry or Telecommand
ETelephony (voice)
FVideo ; television signals
WCombination of any of the above
XNone of the above

Details of Signals

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

Nature of Multiplexing

NNone used
C Code division multiplexing
FFrequency division multiplexing
TTime division multiplexing
WCombination of Frequency-division and Time-division
XNone of the above

Commonly used Ham Radio emission characteristics

Table 1 - Commonly used emission characteristics

Transmission mode

Emission mode coding examples
AM SSB FM PM
Morse A1A
A1B
J2A
J2B
F1B
G1B
Speech A3E J3E F3E G3E
Data (packet) A2D
A1D
J2D
FID
F2D
G1D
G2D
RTTY A2D J2D F2D G2D
Facsimile A2C J2C F2C G2F
FSTV C3F
A3F
J3F
F3F
G3F
SSTV A2F
J2F
J3F
F2F
F3F
G2F
G3F


Modes of operation
Modes CW * AM * FM * SSB * Digital * Echolink * Emission Classification * IRLP * Optical communications
Packet APRS * D-Star
SSTV and ATV SSTV frequencies * SSTV Modes