Comtech EF Data CDD-880 - Manual (Page 116)

CDD-880 Multi Receiver Router Revision 1
Appendix B MN-CDD880
B–2
Table B-1. The VersaFEC ModCod Set
Modulation Code Rate
Spectral
Efficiency,
bps/Hz
Block
size, bits
Typical
Eb/No, for
BER = 5 x 10 -8
Latency at
64 kbps, in
milliseconds
Min. Data
Rate,
CCM mode
Max. Data
Rate,
CCM mode
BPSK 0.488 0.49 2k 2.4 dB 26 16 kbps 2.19 Mbps
QPSK 0.533 1.07 4.1k 2.2 dB 53 18 kbps 4.80 Mbps
QPSK 0.631 1.26 4.1k 2.7 dB 59 21 kbps 5.67 Mbps
QPSK 0.706 1.41 4.1k 3.4 dB 62 23 kbps 6.34 Mbps
QPSK 0.803 1.61 4.1k 3.8 dB 66 26 kbps 7.22 Mbps
8-QAM 0.642 1.93 6.1k 4.6 dB 89 31 kbps 8.67 Mbps
8-QAM 0.711 2.13 6.1k 5.2 dB 93 35 kbps 9.60 Mbps
8-QAM 0.780 2.34 6.1k 5.6 dB 97 38 kbps 10.53 Mbps
16-QAM 0.731 2.93 8.2k 6.3 dB 125 47 kbps 13.16 Mbps
16-QAM 0.780 3.12 8.2k 7.0 dB 129 50 kbps 14.04 Mbps
16-QAM 0.829 3.32 8.2k 7.5 dB 131 54 kbps 14.91 Mbps
16-QAM 0.853 3.41 8.2k 8.0 dB 132 55 kbps 15.35 Mbps
VersaFEC represents the best currently available FEC technology, and is offered with a range of
code rates and modulation types that sufficiently optimize link performance under almost any
conditions. The performance of the VersaFEC codes compared with the Shannon bound is
shown in Figure B‐1:
Figure B‐1. The VersaFEC Codes versus Shannon Capacity
Note that SNR is used in place of Eb/No – a convention for comparing ACM ModCods. SNR is
defined as Eb/No + 10
log
(Spectral Efficiency).