Sec.  2.201   Emission, modulation, and transmission characteristics.

   The following system of designating emission, modulation, and transmission
   characteristics shall be employed.

   (a) Emissions are designated according to their classification and their
   necessary bandwidth.

   (b) A minimum of three symbols are used to describe the basic
   characteristics of radio waves. Emissions are classified and symbolized
   according to the following characteristics:

   (1) First symbol—type of modulation of the main character;

   (2) Second symbol—nature of signal(s) modulating the main carrier;

   (3) Third symbol—type of information to be transmitted.

   Note: A fourth and fifth symbol are provided for additional information and
   are shown in Appendix 6, part A of the ITU Radio Regulations. Use of the
   fourth and fifth symbol is optional. Therefore, the symbols may be used as
   described in Appendix 6, but are not required by the Commission.

   (c) First Symbol—types of modulation of the main carrier:




 (1) Emission of an  N
 unmodulated
   carrier
 (2) Emission in
 which the main
 carrier is
 amplitude-
 modulated
 (including cases
 where sub-carriers
 are angle-
 modulated):
  _Double-sideband.  A
  _Single-sideband,  H
   full carrier....
  _Single-sideband,  R
   reduced or
   variable level
   carrier.........
  _Single-sideband,  J
   suppressed
   carrier.........
  _Independent       B
   sidebands.......
  _Vestigial         C
   sideband........
 (3) Emission in
 which the main
 carrier is angle-
 modulated:
  _Frequency         F
   modulation......
  _Phase modulation  G


   Note: Whenever frequency modulation “F” is indicated, Phase modulation “G”
   is also acceptable.




 (4) Emission in     D
 which the main
 carrier is
 amplitude and
 angle-modulated
    either
 simultaneously or
 in a pre-
 established
  sequence
 (5) Emission of
 pulses:\1\
  _Sequence of       P
   unmodulated
   pulses..........
  _A sequence of
   pulses:
    _Modulated in    K
     amplitude.....
    _Modulated in    L
     width/duration
    _Modulated in    M
     position/phase
    _In which the    Q
     carrier is
     angle-
     modulated
     during the
     period of the
     pulse.........
    _Which is a      V
     combination of
     the foregoing
     or is produced
     by other means
 (6) Cases not       W
 covered above, in
 which an emission
 consists of the
 main carrier
 modulated, either
 simultaneously or
 in a pre-
 established
 sequence, in a
 combination of two
 or more of the
 following modes:
 amplitude, angle,
     pulse
 (7) Cases not       X
 otherwise covered



   ^1 Emissions where the main carrier is directly modulated by a signal which
   has been coded into quantized form (e.g. pulse code modulation) should be
   designated under (2) or (3).

   (d) Second Symbol—nature of signal(s) modulating the main carrier:




 (1) No modulating   0
    signal
 (2) A single        1
 channel containing
 quantized or
   digital
 information
 without the use of
 a modulating sub-
 carrier, excluding
 time-division
  muliplex
 (3) A single        2
 channel containing
 quantized or
   digital
 information with
 the use of a
 modulating sub-
 carrier, excluding
 time-division
 multiplex
 (4) A single        3
 channel containing
  analogue
 information
 (5) Two or more     7
  channels
 containing
 quantized or
   digital
 information
 (6) Two or more     8
  channels
 containing
  analogue
 information
 (7) Composite       9
 system with one or
 more channels
 containing
 quantized or
   digital
 information,
 together with one
 or more channels
 containing
  analogue
 information
 (8) Cases not       X
 otherwise covered


   (e) Third Symbol—type of information to be transmitted: ^2

   ^2 In this context the word “information” does not include information of a
   constant, unvarying nature such as is provided by standard frequency
   emissions, continuous wave and pulse radars, etc.




 (1) No information  N
 transmitted
 (2) Telegraphy_for  A
 aural reception
 (3) Telegraphy_for  B
 automatic
 reception
 (4) Facsimile       C
 (5) Data            D
 transmission,
 telemetry,
 telecommand
 (6) Telephony       E
 (including sound
 broadcasting)
 (7) Television      F
   (video)
 (8) Combination of  W
 the above
 (9) Cases not       X
 otherwise covered


   (f) Type B emission: As an exception to the above principles, damped waves
   are symbolized in the Commission's rules and regulations as type B emission.
   The use of type B emissions is forbidden.

   (g) Whenever the full designation of an emission is necessary, the symbol
   for that emission, as given above, shall be preceded by the necessary
   bandwidth of the emission as indicated in  Sec. 2.202(b)(1).

   [ 49 FR 48697 , Dec. 14, 1984]