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A.1
Forward Error Correction Options
As standard, the SLM-5650 Modem is equipped with three Forward Error Correction
encoders/decoders – Viterbi, concatenated Reed-Solomon, and Trellis (which is available with
the 8-PSK FAST option). The constraint lengths and encoding polynomials are not only Open
Network compatible, but are also Closed Network compatible with the vast majority of
existing modems from other manufacturers. The SLM-5650 also provides the capability to
disable all FEC allowing the modem to run uncoded.
Turbo Coding represents a very significant development in the area of FEC, and optionally,
the SLM-5650 may be fitted with the Turbo Product Codec. It is a plug-in daughter card
(SIMM module), which can be upgraded in the field. There are four speed grades of the Turbo
FEC. The data rate capabilities are from:
Appendix A. OPTIONS
Low Rate
64 kbps to 5 Mbps
Low Rate
64 kbps to 10 Mbps
Low Rate
64 kbps to 20 Mbps
High Rate
64 kbps to 51.84 Mbps
A–1
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