Comtech EF Data CDM-710 Installation And Operation Manual page 232

CDM-710 Broadcast Satellite Modem
Eb/No Measurement
Example: In the diagram that follows, the (Co+No)/No measured is 4.6 dB. If Rate 1/2 QPSK is
used, this corresponds to an Eb/No of approximately 2.8 dB (DVB-S2) or 3.1 dB (DVB-S).
The relationship used to derive the table values is as follows (only simple way for DVB-S2):
Eb/No = 10log10(10
•
Eb/No and(Co+No)/No are expressed in dB, and
•
Spectral Efficiency includes the modulation type, code rate, overhead and
framing and is shown in Table B-1 and Table B-2.
The equation above applies to DVB-S and DVB-DSNG, or use the traditional relationship:
Eb/No = 10 log
•
Eb/No and(Co+No)/No are expressed in dB;
•
FEC Code Rate (Composite) = 3/4*(188/204), 7/8*(188/204), etc.
•
bits/symbol = 2 for QPSK, 3 for 8-PSK, 4 for 16-QAM;
•
Pay close attention to the sign of the middle term.
((Co+No)/No)/10)
-1) – 10log10(Spectral Efficiency)
where:
((Co+No)/No)/10)
(10 -1)- 10 log
10
where:
(FEC Code Rate) 10 log
10
B–2
Revision 11
MN/CDM710.IOM
(bits/symbol)
10