Comtech EF Data SLM-5650A - Manual (Page 395)

D–1
Appendix D. MODEM OPTIONS
D.1 Forward Error Correction Options
As standard, the SLM-5650A Satellite Modem is equipped with three Forward Error Correction
(FEC) encoders/decoders: Viterbi, concatenated Reed-Solomon, and Trellis (available with the
8PSK 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-5650A 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-5650A may be fitted with Turbo Product Coding (TPC) and Low-Density Parity Check
(LDPC) coding.
There are six speed grades of these Advanced FECs; the data rate limits are as follows:
Low Rate 64 kbps to 2.5 Mbps
64 kbps to 5 Mbps
64 kbps to 10 Mbps
64 kbps to 20 Mbps
High Rate 64 kbps to 51.84 Mbps
64 kbps to 155.52 Mbps ( TPC only)