| ITU Emissions are designated using a three-character code. The first character gives you the type of main modulation (or carrier type), the second character gives you the signals that are modifying the main carrier, and the third character gives you the type of information transmitted.
Second Character:
- 0 No modulating signal
- 1 Single-channel digital information, no modulation
- 2 Single-channel digital information with modulation
- 3 Single channel carrying analog information
- 7 Two or more channels carrying digital information
- 8 Two or more channels carrying analog information
- 9 Combination of digital and analog information
As an example, regular old Morse Code is designated as A1A (amplitude-modulated carrier, digital with no signal modulation, telegraphy for human hearing).
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