Comtech EF Data CDM-600/600L User Manual
Page 129
CDM-600/600L Open Network Satellite Modem
Revision 3
Forward Error Correction Options
MN/CDM600L.IOM
6–9
Table 6-6. Turbo Product Coding Processing Delay Comparison
FEC Mode (64 kbps data rate)
End-to-end delay, ms
Viterbi, Rate 1/2
12
Sequential, Rate 1/2
74
Viterbi Rate 1/2 + Reed Solomon
266
Sequential Rate 1/2 + Reed Solomon
522
Turbo Product Coding, Rate 3/4, O/QPSK
47
Turbo Product Coding, Rate 21/44, BPSK
64
Turbo Product Coding, Rate 5/16, BPSK
48
Turbo Product Coding, Rate 7/8, O/QPSK
245 *
Turbo Product Coding, Rate 0.95, O/QPSK
69
LDPC Coding, Rate 1/2
248
LDPC Coding, Rate 2/3, O/QPSK
296
LDPC Coding, Rate 2/3, 8-PSK, 8-QAM
350
LDPC Coding, Rate 3/4, O/QPSK
321
LDPC Coding, Rate 3/4, 8-PSK, 8-QAM, 16-QAM
395
*A larger block is used for the Rate 7/8 code, which increases decoding delay.
Note that, in all cases, the delay is inversely proportional to data rate; so for 128 kbps, the delay
values would be half of those shown above. It can be seen that the concatenated Reed-Solomon
cases increase the delay significantly (due mainly to interleaving/de-interleaving), while the TPC
cases yield delays which are less than or equal to Sequential decoding.