9D37 D
 The properly operating HF DSC transmitter in the GMDSS system differs from older non-GMDSS SSB voice transmitters in what way?
A. 170 Hz shift is used rather than 1700 kHz.
B. Frequency response is flat rather than 6dB/Octave pre-emphasis.
C. Direct FSK is used rather than AFSK.
D. Required carrier stability.
