Comtech EF Data CDM-570A Installation And Operation Manual page 558

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Appendix H
Example: In the above diagram, the (Co+No)/No measured is 4.6 dB. If Rate 1/2 QPSK is being
used, this would correspond to an E
The exact relationship used to derive the table values is as follows:
E /N = 10 log
b 0 10
Where:
•
E /N and (Co+No)/No are expressed in dB
b 0
•
Bits/symbol = 1 for BPSK
•
Bits/symbol = 2 for QPSK
• Bits/symbol = 3 for 8-PSK/8-QAM
•
Bits/symbol = 4 for 16-QAM
• Code Rate for 'uncoded' = 1
Pay close attention to the sign of the middle term
/N
b
(Co+No/No )/10)
(10 -1) - 10 log
of approximately 2.6 dB.
0
(FEC Code Rate) - 10 log
10
H–2
MN-CDM570A
Revision 3
(bits/symbol)
10