Comtech EF Data SDM-300A - Manual (Page 381)

SDM-300A Satellite Modem Revision 6
Specifications MN/SDM300A.IOM
19–25
19.8.2.1 Transmit Clock Switching Due to Failure of Selected Clock
The modem will automatically switch the TX clock source to SCT internal on failure of
terminal timing.
19.8.2.2 Transmit Clock Phase Adjustment
The operator can set the TX clock phase to Normal, Inverted, or Auto mode.
19.8.2.3 Transmit Data Phase Adjustment
The operator can set the TX data phase to Normal or Inverted.
19.8.2.4 Transmit Data Stable Condition
Transmitted data to the Modulator will be held stable (all 1’s) for the fault conditions shown
in the Fault Tree, then set TX AIS.
19.8.2.5 Doppler/Plesiochronous Buffer Clock Source
The operator can set the Doppler/Plesiochronous buffer clock reference from the following
sources.
• The RX satellite clock (Bypass Mode).
• The TX terrestrial clock (TT). Must be within ± 100 PPM of the nominal receive
data rate. Or it can be any multiple of 8 kHz as long as it is ≥ 64 kHz ≤ 4.376 MHz
or any multiple of 600 Hz as long as it is ≥ 2.4 kHz ≤ 64 kHz.
• The external clock (Master Clock) input, must be within ± 100 PPM of the
programmed value. Or it can be any multiple of 8 kHz as long as it is ≥ 64 kHz
≤ 4.376 MHz or any multiple of 600 Hz as long as it is ≥ 2.4 kHz ≤ 64 kHz.
• SCT/Internal, ± 10 PPM or (with high stability option), ± 0.2 PPM.