Comtech EF Data CDM-840 - Manual (Page 184)

CDM-840 Remote Router Revision 2
Appendix B MN-CDM840
B–4
Table B-1 specifies the 12 modulations types / code rates that comprise the VersaFEC MODCOD
Set. These chosen modulation types (BPSK, QPSK, 8-QAM and 16-QAM) and code rates afford a
continuous progression of performance in terms of both Eb/No and spectral efficiency – essential
aspects of a well-engineered ACM system.
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
B.3.1 Range of Data Rates
See Sect. 1.4 SUMMARY OF SPECIFICATIONS for the range of available data rates.
B.4 CDM-840 Rx/Tx Error Performance Characteristics
For Rx DVB-S2 Operation: Figure B-2 through Figure B-5 illustrate the guaranteed error
performance characteristics of the CDM-840 while receiving with Normal frames (64,800 bits),
Pilots ON.
For Tx VersaFEC Operation: Figure B-6 through Figure B-9 illustrate the guaranteed error
performance characteristics of the CDM-840.