Sec. 2.201  Emission, modulation, and transmission characteristics.

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

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    (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 unmodulated carrier............................   N
  (2) Emission in which the main carrier is amplitude-modulated         
 (including cases where sub-carriers are angle-modulated):..........    
  --Double-sideband.................................................   A
  --Single-sideband, full carrier...................................   H
  --Single-sideband, reduced or variable level carrier..............   R
  --Single-sideband, suppressed carrier.............................   J
  --Independent sidebands...........................................   B
  --Vestigial sideband..............................................   C
  (3) Emission in which the main carrier is angle-modulated:........    
  --Frequency modulation............................................   F
  --Phase modulation................................................   G
                                                                        


    Note: Whenever frequency modulation ``F'' is indicated, Phase 
modulation ``G'' is also acceptable.


                                                                        
                                                                        
                                                                        
  (4) Emission in which the main carrier is amplitude and angle-        
 modulated either simultaneously or in a pre-established sequence...   D
  (5) Emission of pulses:\1\........................................    
  --Sequence of unmodulated pulses..................................   P
  --A sequence of pulses:                                               
    --Modulated in amplitude........................................   K
    --Modulated in width/duration...................................   L
    --Modulated in position/phase...................................   M
    --In which the carrier is angle-modulated during the period of      
     the pulse......................................................   Q
    --Which is a combination of the foregoing or is produced by         
     other means....................................................   V
  (6) Cases not 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...........................   W
  (7) Cases not otherwise covered...................................   X
                                                                        

      
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    \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).
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    (d) Second Symbol--nature of sig-nal(s) modulating the main carrier:

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

    (e) Third Symbol--type of information to be transmitted:\2\
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    \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 transmitted....................................   N
  (2) Telegraphy--for aural reception...............................   A

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  (3) Telegraphy--for automatic reception...........................   B
  (4) Facsimile.....................................................   C
  (5) Data transmission, telemetry, telecommand.....................   D
  (6) Telephony (including sound broadcasting)......................   E
  (7) Television (video)............................................   F
  (8) Combination of the above......................................   W
  (9) Cases not otherwise covered...................................   X
                                                                        

    (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 1997 FR 48697 , Dec. 14, 1984]