Comtech EF Data Vipersat SLM-5650A, Installation And Operation Manual

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SLM-5650A Satellite Modem
Revision 10
Appendix H G–7 MN-SLM-5650A
Figure G-3. Same Link Using SLM-5650A and DoubleTalk Carrier-in-Carrier
Figure G-4. Duplex Link Optimization
The SLM-5650A CnC module operates on the near-zero signal before the demodulator, and is
waveform-agnostic. This means that no prior knowledge of the underlying modulation, FEC, or
any other waveform specific parameter is required in order to perform the signal suppression
operation. The only caveat to this is that the waveform must be
sufficiently random .
Because acquiring the delay and frequency offset of the interfering carrier is fundamentally a
correlation operation, anything deterministic in the interfering carrier (within the correlation
window of the algorithm) will potentially produce false correlation peaks and result in incorrect
delays and/or frequency. Normally, this is not a problem, since energy dispersal techniques are
used in the vast majority of commercial and military modems. However, it is something that must
be kept in mind when troubleshooting a system that uses the CnC technique for signal
suppression.