Figure 7-2. Versafec Codes Versus Shannon Capacity - 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

Forward Error Correction Options

The performance of the VersaFEC codes compared with the Shannon bound is shown in Figure 7-2.

This puts the performance of VersaFEC at or near the DVB-S2 performance with 16 kbit blocks.

Figure 7-2. VersaFEC Codes versus Shannon Capacity

Note that SNR is used in place of Eb/No – a convention for comparing ACM ModCods. SNR is

defined as Eb/No + 10log(Spectral Efficiency).

VersaFEC requires both the correct hardware module (PL-0000264) to be installed

in the CDM-625 and Firmware Version 1.3.0 (or higher). ACM requires Firmware

Version 1.4.0 (or higher).