Comtech EF Data SNM-1001L - Manual (Page 263)

SNM-1001L Satellite Modem Revision 1
Specifications MN/SNM1001L.IOM
A–25
A.10.6 Doppler/Plesiochronous Buffer Clock Source
The operator from the following sources can select the Doppler/Plesiochronous buffer
clock reference.
• The RX satellite clock (Bypass Mode).
• The TX terrestrial clock (TT). Must be within ± 100 PPM of the nominal receive
data rate. Or, with the Asymmetric Timing Option, it can be any multiple of 1 kHz
as long as it is
≥ 64 kHz ≤ 5 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, with the Asymmetric Timing Option, it can be any
multiple of 1 kHz as long as it is
≥ 64 kHz ≤ 5 MHz or any multiple of 600 Hz as
long as it is ≥ 2.4 kHz ≤ 64 kHz.
• SCT/Internal, ± 10 PPM or per high stability option.
A.10.7 RX Clock Switching Due to Failure of Selected Clock
The modem will automatically switch the receive clock source to RX satellite on failure of
the selected clock.
A.10.8 RX Clock Phase Adjustment
The operator can set the RX clock phase to Normal or Inverted.
A.10.9 RX Clock Jitter
The RX clock will have less than 2% jitter RMS for a BER of 10-7 or less.
A.10.10 RX Data Phase Adjustment
The operator can set the RX data phase to Normal or Inverted.
A.10.11 Buffer Centering
The operator can set the buffer to 50%. The modem will automatically set the buffer to
50% after receive signal acquisition or a buffer overflow/underflow.