Emission Classification

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

N	Unmodulated carrier
A	Double-sideband amplitude modulation
H	Single-sideband with full carrier
R	Single-sideband with reduced-carrier or variable carrier
J	Single-sideband with suppressed carrier
B	Independent sideband (two sidebands containing different signals)
C	Vestigial sideband e.g. NTSC
F	Frequency modulation
G	Phase modulation
D	Combination of AM and FM or PM
P	Sequence of pulses without modulation
K	Pulse amplitude modulation
L	Pulse width modulation
M	Pulse position modulation
Q	Sequence of pulses, phase or frequency modulation within each pulse
V	Combination of pulse modulation methods
W	Combination of any of the above
X	None of the above

Nature of modulating signals

0	No modulating signal
1	One channel containing digital information, no subcarrier
2	One channel containing digital information, using a subcarrier
3	One channel containing analogue information
7	More than one channel containing digital information
8	More than one channel containing analogue information
9	Combination of analogue and digital channels
X	None of the above

Type of information being transmitted

N	No transmitted information
A	Aural telegraphy, intended to be decoded by ear, such as Morse code
B	Electronic telegraphy, intended to be decoded by machine ; Radioteletype and digital modes
C	Facsimile
D	Telemetry or Telecommand
E	Telephony (voice)
F	Video ; television signals
W	Combination of any of the above
X	None of the above

Details of Signals

A	Two-condition code, elements vary in quantity and duration
B	Two-condition code, elements fixed in quantity and duration
C	Two-condition code, elements fixed in quantity and duration, error-correction included
D	Four-condition code, one condition per "signal element"
E	Multi-condition code, one condition per "signal element"
F	Multi-condition code, one character represented by one or more conditions
G	Monophonic broadcast-quality sound
H	Stereophonic or quadraphonic broadcast-quality sound
J	Commercial-quality sound (non-broadcast)
K	Commercial-quality sound—frequency inversion and-or "band-splitting" employed
L	Commercial-quality sound, independent FM signals, such as pilot tones, used to control the demodulated signal
M	Greyscale images or video
N	Full-color images or video
W	Combination of two or more of the above
X	None of the above

Nature of Multiplexing

N	None used
C	Code division multiplexing
F	Frequency division multiplexing
T	Time division multiplexing
W	Combination of Frequency-division and Time-division
X	None 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