Comtech EF Data CDM-570 Installation And Operation Manual page 344

CDM-570/570L Satellite Modem with Optional IP Module
Appendix B
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
/N
b 0
(Co+No/No )/10)
(10 -1) - 10 log
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
Note: Pay close attention to the sign of the middle term
of approximately 2.6 dB.
(FEC Code Rate) - 10 log
10
B–2
Revision 12
MN/CDM570L.IOM
(bits/symbol)
10