Comtech EF Data CDM-600/600L - Manual (Page 130)

CDM-600/600L Open Network Satellite Modem Revision 3
Forward Error Correction Options MN/CDM600L.IOM
6–10
Table 6-7. Comparison of all Comtech EF Data TPC and LDPC Modes
(CDM-600L with LDPC/TPC Codec and Firmware Version 1.3.0)
(CDM-600 with LDPC/TPC Codec and Firmware Version 1.6.0)
Mode
Eb/No at
BER = 10
-6
(typical)
Eb/No at
BER = 10
-8
(typical)
Spectral
Efficiency
(bps per
Hertz)
Symbol Rate
Occupied *
Bandwidth for
1 Mbps
Carrier
QPSK Rate 1/2 Viterbi * 5.5 dB 6.8 dB 1.00 bps/Hz 1.0 x bit rate 1190 kHz
BPSK Rate 1/2 LDPC 1.7 dB 1.9 dB 0.50 bps/Hz 2.0 x bit rate 2380 kHz
BPSK Rate 21/44 TPC 2.6 dB 2.9 dB 0.48 bps/Hz 2.1 x bit rate 2493 kHz
BPSK Rate 5/16 TPC 2.1 dB 2.4 dB 0.31 bps/Hz 3.2 x bit rate 3808 kHz
QPSK/OQPSK Rate 1/2 LDPC 1.7 dB 1.9 dB 1.00 bps/Hz 1.0 x bit rate 1190 kHz
QPSK/OQPSK Rate 1/2 TPC 2.6 dB 2.8 dB 0.96 bps/Hz 1.05 x bit rate 1246 kHz
QPSK/OQPSK Rate 2/3 LDPC 2.1 dB 2.3 dB 1.33 bps/Hz 0.75 x bit rate 892 kHz
QPSK/OQPSK Rate 3/4 LDPC 2.7 dB 2.9 dB 1.50 bps/Hz 0.67 x bit rate 793 kHz
QPSK/OQPSK Rate 3/4 TPC 3.3 dB 4.0 dB 1.50 bps/Hz 0.67 x bit rate 793 kHz
QPSK/OQSK Rate 7/8 TPC 4.0 dB 4.2 dB 1.75 bps/Hz 0.57 x bit rate 678 kHz
QPSK/OQPSK Rate 0.95 TPC 6.0 dB 6.5 dB 1.90 bps/Hz 0.53 x bit rate 626 kHz
8-PSK Rate 2/3 TCM **
and RS (IESS-310)
5.6 dB 6.2 dB 1.82 bps/Hz 0.56 x bit rate 666 kHz
8-QAM Rate 2/3 LDPC 4.3 dB 4.5 dB 2.00 bps/Hz 0.50 x bit rate 595 kHz
8-QAM Rate 3/4 LDPC 4.7 dB 5.0 dB 2.25 bps/Hz 0.44 x bit rate 529 kHz
8-PSK Rate 3/4 TPC 5.7 dB 6.3 dB 2.25 bps/Hz 0.44 x bit rate 529 kHz
8-PSK Rate 7/8 TPC 6.6 dB 6.8 dB 2.62 bps/Hz 0.38 x bit rate 453 kHz
8-PSK Rate 0.95 TPC 8.9 dB 9.9 dB 2.85 bps/Hz 0.35 x bit rate 377 kHz
16-QAM Rate 3/4 LDPC 6.4 dB 6.6 dB 3.00 bps/Hz 0.33 x bit rate 396 kHz
16-QAM Rate 3/4 TPC 7.0 dB 7.7 dB 3.00 bps/Hz 0.33 x bit rate 396 kHz
16-QAM Rate 7/8 TPC 7.7 dB 7.9 dB 3.50 bps/Hz 0.28 x bit rate 340 kHz
16-QAM Rate 3/4 **
Viterbi/Reed-Solomon
7.5 dB 8.0 dB 2.73 bps/Hz 0.37 x bit rate 435 kHz
16-QAM Rate 7/8 **
Viterbi/Reed-Solomon
9.0 dB 9.5 dB 3.18 bps/Hz 0.31 x bit rate 374 kHz
* 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-600L/600 transmit filtering.
** Included for comparative purposes
Table 6-8. TPC and LDPC Summary
FOR AGAINST
Exceptionally good BER performance – significant improvement compared with
every other FEC method in use today
Nothing!
Most modes have no pronounced threshold effect – fails gracefully
Exceptional bandwidth efficiency
Coding gain independent of data rate (in this implementation)
Low decoding delay for TPC
Easy field upgrade in CDM-600/600L