Uncoded Operation (No Fec) - Comtech EF Data SNM-1001L Installation And Operation Manual

SNM-1001L Satellite Modem
Forward Error Correction Options
Note: For additional data, refer to Appendix A, for BER specifications.
Mode
QPSK Rate 1/2 Viterbi *
BPSK Rate 21/44 Turbo
BPSK Rate 5/16 Turbo
Offset QPSK Rate 1/2 Turbo
Offset QPSK Rate 3/4 Turbo
8-PSK Rate 2/3 TCM **
and RS (IESS-310)
8-PSK Rate 3/4 Turbo
*
The occupied bandwidth is defined at the width of the transmitted spectrum taken at the -10 dB points on
the plot of power spectral density. This equates to 1.19 x symbol rate for the SNM-1001L transmit
filtering.
**
Included for comparative purposes.
It can be seen that the 8-PSK Rate 3/4 Turbo performance closely approaches that of the Rate
2/3 TCM/Reed-Solomon case – the BER performance is within approximately 0.4 dB. However,
it should be noted that the Rate 3/4 Turbo mode is 20% more bandwidth efficient than the TCM
case. The additional advantages of Turbo (lower delay, performance during fades etc) should
also be considered.
7.4

Uncoded Operation (No FEC)

Eb/No at Eb/No at
-6
BER = 10 BER = 10
6.0 dB 7.2 dB
3.0 dB 3.3 dB
< 4.0 dB < 4.0 dB
3.0 dB 3.5 dB
3.9 dB 4.3 dB
6.1 dB 6.6 dB
7.0 dB 8.0 dB
7–4
Spectral
Symbol Rate
-8
Efficiency
1.00 bps/Hz 1.0 x bit rate
0.48 bps/Hz 2.1 x bit rate
0.31 bps/Hz 3.2 x bit rate
1.00 bps/Hz 1.0 x bit rate
1.50 bps/Hz 0.67 x bit rate
1.82 bps/Hz 0.56 x bit rate
2.25 bps/Hz 0.44 x bit rate
Revision 1
MN/SNM1001L.IOM
Occupied *
Bandwidth for
1 Mbps Carrier
1190 kHz
2493 kHz
3808 kHz
1190 kHz
793 kHz
666 kHz
529 kHz