Co+No)/No Example - Comtech EF Data CDM-425 Installation And Operation Manual

G.1.1 (Co+No)/No Example
In Figure G-1, the (Co+No)/No measured is 4.6 dB. If Rate 1/2 QPSK is used, this corresponds to
an E /N of approximately 2.6 dB. The exact relationship used to derive the table values is as
b 0
follows:
E /N =10log
b 0
Where:
•
E /N
b
•
bits/symbol = 1 for BPSK;
•
bits/symbol = 2 for QPSK;
•
bits/symbol = 3 for 8-PSK/8-QAM;
•
bits/symbol = 4 for 16-QAM;
•
FEC Code Rate for 'uncoded' = 1.
Pay close attention to the sign of the middle term.
See Figure G-2 for the Eb/No Table.
Appendix G
Figure G-1. (Co+No)/No Measured Example
(10 (Co+No/No)/10) -1)-10log
10
and (Co+No)/ No are expressed in dB;
0
CDM-425 Advanced Satellite Modem
(FEC Code Rate)-10log
10
G–2
Revision 0
(bits/symbol)
10
MN-CDM-425