Product specifications

CDM-710 Broadcast Satellite Modem Revision 11
Eb/No Measurement MN/CDM710.IOM
B–2
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
((Co+No)/No)/10)
-1) – 10log10(Spectral Efficiency)
where:
• 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
10
(10
((Co+No)/No)/10)
-1)- 10 log
10
(FEC Code Rate) 10 log
10
(bits/symbol)
where:
• 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.