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CDM-625A Advanced Satellite Modem
Appendix B
Table B-6. Comparison of all Comtech EF Data TPC/LDPC Modes (CDM-625A with
Mode
QPSK Rate 1/2 Viterbi **
BPSK Rate 1/2 LDPC
BPSK Rate 21/44 TPC
BPSK Rate 5/16 TPC
QPSK/OQPSK Rate 1/2 LDPC
QPSK/OQPSK Rate 21/44 TPC
QPSK/OQPSK Rate 2/3 LDPC
QPSK/OQPSK Rate 3/4 LDPC
QPSK/OQPSK Rate 3/4 TPC
QPSK/OQSK Rate 7/8 TPC
QPSK/OQPSK Rate 0.95 TPC
8-PSK Rate 2/3 TCM **
and RS (IESS-310)
8-QAM Rate 2/3 LDPC
8-QAM Rate 3/4 LDPC
8-PSK/8-QAM Rate 3/4 TPC
8-PSK/8-QAM Rate 7/8 TPC
8-PSK/8-QAM Rate 0.95 TPC
16-QAM Rate 3/4 LDPC
16-QAM Rate 3/4 TPC
16-QAM Rate 7/8 TPC
16-QAM Rate 3/4 **
Viterbi/Reed-Solomon
16-QAM Rate 7/8 **
Viterbi/Reed-Solomon
* 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 CDM-625A
transmit filtering.
** Included for comparative purposes
TPC/LDPC Codec)
Eb/No at
Eb/No at
BER = 10
BER = 10
-6
-8
(typical)
(typical)
5.5 dB
6.8 dB
1.7 dB
1.9 dB
2.8 dB
3.0 dB
2.4 dB
3.0 dB
1.7 dB
1.9 dB
2.8 dB
3.3 dB
2.1 dB
2.4 dB
2.7 dB
2.9 dB
3.4 dB
4.0 dB
4.2 dB
4.3 dB
6.0 dB
6.5 dB
5.6 dB
6.2 dB
4.3 dB
4.6 dB
5.3 dB
5.5 dB
6.1 dB
6.7 dB
6.7 dB
6.9 dB
9.2 dB
10.2 dB
6.7 dB
6.8 dB
7.4 dB
8.1 dB
7.9 dB
8.1 dB
7.5 dB
8.0 dB
9.0 dB
9.5 dB
B–11
Spectral
Efficiency
Symbol Rate
(bps per Hz)
1.00 bps/Hz
1.0 x bit rate
0.50 bps/Hz
2.0 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
0.96 bps/Hz
1.05 x bit rate
1.33 bps/Hz
0.75 x bit rate
1.50 bps/Hz
0.67 x bit rate
1.50 bps/Hz
0.67 x bit rate
1.75 bps/Hz
0.57 x bit rate
1.90 bps/Hz
0.53 x bit rate
1.82 bps/Hz
0.56 x bit rate
2.00 bps/Hz
0.50 x bit rate
2.25 bps/Hz
0.44 x bit rate
2.25 bps/Hz
0.44 x bit rate
2.62 bps/Hz
0.38 x bit rate
2.85 bps/Hz
0.35 x bit rate
3.00 bps/Hz
0.33 x bit rate
3.00 bps/Hz
0.33 x bit rate
3.50 bps/Hz
0.28 x bit rate
2.73 bps/Hz
0.37 x bit rate
3.18 bps/Hz
0.31 x bit rate
MN-CDM625A
Revision 4
Occupied *
Bandwidth for
1 Mbps Carrier
1190 kHz
2380 kHz
2493 kHz
3808 kHz
1190 kHz
1246 kHz
892 kHz
793 kHz
793 kHz
678 kHz
626 kHz
666 kHz
595 kHz
529 kHz
529 kHz
453 kHz
377 kHz
396 kHz
396 kHz
340 kHz
435 kHz
374 kHz
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