Comtech EF Data Vipersat CDD-562L, Installation And Operation Manual

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CDD-562L/564 Demodulator with IP Module Revision 2
Appendix B MN/CDD564L.IOM
B–3
B.2.3 Comparison of All TPC Modes (Contains Additional Information)
Mode
Eb/No at
BER = 10
-6
Guaranteed
(Typical in
parentheses)
Eb/No at
BER = 10
-8
Guaranteed
(Typical in
parentheses)
Spectral
Efficiency
Symbol Rate
Occupied
Bandwidth
for 1 Mbps
Carrier
QPSK
Rate 3/4 Turbo 3.8 dB
(3.4 dB)
4.4 dB
(4.0 dB)
1.50 bits/Hz 0.67 x bit rate 793 kHz
QPSK
Rate 0.95 Turbo 6.4 dB
(6.0 dB)
6.9 dB
(6.5 dB)
1.90 bits/Hz 0.53 x bit rate 626 kHz
8-PSK Rate 3/4 Turbo
6.2 dB
(5.8 dB)
6.8 dB
(6.3 dB)
2.25 bits/Hz 0.44 x bit rate 529 kHz
8-PSK Rate 0.95 Turbo
9.3 dB
(8.9 dB)
10.3dB
(9.9 dB)
2.85 bits/Hz 0.35 x bit rate 377 kHz
16-QAM Rate 3/4 Turbo
7.4 dB
(7.0 dB)
8.2 dB
(7.7 dB)
3.00 bits/Hz 0.33 x bit rate 396 kHz
The additional advantages of Turbo – lower delay, performance during fades, etc. – should also
be considered.
Table B-2. Turbo Product Coding Summary
FOR AGAINST
•
Exceptionally good BER performance – significant
improvement compared with every other FEC method in
use today
Nothing!
•
No pronounced threshold effect – fails gracefully
•
Exceptional bandwidth efficiency
•
Coding gain independent of data rate (in this
implementation)
•
Low decoding delay
•
Easy field upgrade