Comtech EF Data SLM-3650 Installation And Operation Manual page 323

SLM-3650 Satellite Modem
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Table A-30.Turbo Product Coding Processing Delay Comparison
FEC Mode (64 kbps data rate)
Viterbi, Rate 1/2
Sequential, Rate 1/2
Viterbi Rate 1/2 + Reed-Solomon
Sequential Rate 1/2 + Reed-Solomon
Turbo Product Coding, Rate 3/4, {O}QPSK
Turbo Product Coding, Rate 21/44, BPSK
Turbo Product Coding, Rate 5/16, BPSK
Note: In all cases, the delay is inversely proportional to data rate, so for 128 kbps, the
delay values would be half of those shown above.
It can be clearly seen that the concatenated Reed-Solomon cases increase the delay very
significantly (due mainly to interleaving/de-interleaving), while the TPC cases yield
delays which are less than or equal to Sequential decoding.
A.5.3 Comparison of all TPC Modes
Mode
QPSK Rate 1/2 Viterbi
(see Note 1)
BPSK Rate 21/44 Turbo
BPSK Rate 5/16 Turbo
{O}QPSK Rate 1/2 Turbo
{O}QPSK Rate 3/4 Turbo
8-PSK Rate 2/3 TCM
and R-S (IESS-310)
(see Note 2)
8-PSK Rate 3/4 Turbo
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Eb/No at Eb/No at
BER = 10 -6 BER = 10 -8
3.8 dB 7.2 dB
2.8 dB 3.3 dB
< 4.0 < 4.0 dB
3.5 dB
3.0 dB
4.3 dB
3.9 dB
6.1 dB 6.6 dB
7.0 dB 8.0 dB
A–95
End-to-end delay, ms
12
74
266
522
79
64
48
Spectral
Symbol Rate
Efficiency
1.00 bits/Hz 1.0 x bit rate
0.48 bits/Hz 2.1 x bit rate
0.31 bits/Hz 3.2 x bit rate
1.00 bits/Hz 1.0 x bit rate
1.50 bits/Hz 0.67 x bit rate
1.82 bits/Hz 0.56 x bit rate
2.25 bits/Hz 0.44 x bit rate
Revision 3
MN/SLM3650.IOM
Occupied *
Bandwidth for 1
Mbps Carrier
1190 kHz
2493 kHz
3808 kHz
1190 kHz
793 kHz
666 kHz
529 kHz