Comtech EF Data CDM-625A Installation And Operation Manual page 687

CDM-625A Advanced Satellite Modem
Appendix M
Modulation
BPSK
QPSK
QPSK
QPSK
QPSK
8-QAM
8-QAM
8-QAM
16-QAM
16-QAM
16-QAM
16-QAM
The VersaFEC codes compared with the Shannon bound are shown in Figure M-2. It can be seen
that the performance of VersaFEC at or near the DVB-S2 performance with 16 kbit blocks.
Note that SNR is used in place of Eb/No, a convention for comparing ACM ModCods. SNR is
defined as Eb/No + 10
Table M-1. The VersaFEC ModCod set
Spectral
Code Block
efficiency,
Rate size, bits
bps/Hz
0.488 0.49 2k
0.533 1.07 4.1k
0.631 1.26 4.1k
0.706 1.41 4.1k
0.803 1.61 4.1k
0.642 1.93 6.1k
0.711 2.13 6.1k
0.780 2.34 6.1k
0.731 2.93 8.2k
0.780 3.12 8.2k
0.829 3.32 8.2k
0.853 3.41 8.2k
(Spectral Efficiency).
log
Figure M-2. VersaFEC Codes vs. Constrained Capacity
Typical Latency at
Eb/No, for 64 kbps, in
BER = 5 x 10 milliseconds
-8
2.4 dB 26
2.2 dB 53
2.7 dB 59
3.4 dB 62
3.8 dB 66
4.6 dB 89
5.2 dB 93
5.6 dB 97
6.3 dB 125
7.0 dB 129
7.5 dB 131
8.0 dB 132
M–7
MN-CDM625A
Revision 4
Min. Max.
Data Rate, Data Rate,
CCM mode CCM mode
18 kbps 5.7 Mbps
20 kbps 10 Mbps
23 kbps 10 Mbps
26 kbps 10 Mbps
28 kbps 12 Mbps
35 kbps 12 Mbps
39 kbps 12 Mbps
43 kbps 12 Mbps
53 kbps 12 Mbps
57 kbps 14 Mbps
60 kbps 14 Mbps
62 kbps 16 Mbps