ITU Radio Regulations

Emission Designations

The ITU uses an internationally agreed system for classifying radio frequency signals.  Each type of radio emission is classified according to a number of factors which describe the characteristics of the signal – not the transmitter used

This classification, referred to as the Emission Designation, has a minimum of 3 characters, showing:

1. Type of Modulation

example:  J = Single-sideband, suppressed carrier

example:  F = Frequency modulation

2. Nature of modulating signal

example:  1 = One channel containing digital information, no subcarrier

example:  3 = One channel containing analogue information

3. Type of information transmitted

example:  D = Data, e.g. RTTY

example:  E = Telephony, e.g. voice

For purposes of the exam, these emission designations should be known:

  • A1A = CW (Morse, on/off keying of the carrier)
  • J3E = SSB (single sideband, suppressed carrier, speech)
  • A3E = AM (amplitude modulation, speech)
  • F3E = FM (frequency modulation, speech)
  • F1B, F2B, J2B = RTTY / AMTOR
  • F1D, F2D, J2D = Packet / Data