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Comtech EF Data CDM-600/600L User Manual

Page 188

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CDM-600/600L Open Network Satellite Modem

Revision 3

Appendix B

MN/CDM600L.IOM

B–2

Example: In the diagram that follows, the (Co+No)/No measured is 4.6 dB. If Rate 1/2 QPSK is
being used, this would correspond to an Eb/No of approximately 2.6 dB.




















The exact relationship used to derive the table values is as follows:

E

b

/N

0

= 10 log

10

(10

(Co+No/No )/10)

-1) - 10 log

10

(FEC Code Rate) - 10 log

10

(bits/symbol)

where:

• E

b

/N

0

and (Co+No)/No are expressed in dB

• 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