Figure 10-3. Same Link Using Cdm-625 And Doubletalk Carrier-In-Carrier; Figure 10-4. Duplex Link Optimization - Comtech EF Data CDM-625 Installation And Operation Manual

Advanced satellite modem (18 kbps – 25 mbps)

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CDM-625 Advanced Satellite Modem

DoubleTalk Carrier-in-Carrier Option

Figure 10-3. Same Link Using CDM-625 and DoubleTalk Carrier-in-Carrier

The CDM-625 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

utilized in the vast majority of commercial and military modems. However, it is something that