Comtech EF Data CDM-625A Installation And Operation Manual page 541

CDM-625A Advanced Satellite Modem
Appendix B
CAUTION – You must take care not to operate the demodulator near its sync
threshold. Small fluctuations in Eb/No may cause total loss of the link and, as a result,
the demodulator will need to re-acquire the signal.
• Exceptionally good BER performance –
several orders of magnitude improvement in
link BER under given link conditions.
• Very small additional bandwidth expansion.
Table B-3. Concatenated RS Coding Summary
FOR
B–5
AGAINST
• Very pronounced threshold effect – does not
fail gracefully in poor Eb/No conditions.
Additional coding overhead actually degrades
sync threshold, and reduces link fade margin.
• Significant processing delay (~25 kbps) – not
good for voice or IP applications.
• Adds to demod acquisition time.
• Higher coding gain methods with much lower
latency now available.
NOT RECOMMENDED FOR NEW
LINKS!
MN-CDM625A
Revision 4