Comtech EF Data CDM-710 Installation And Operation Manual page 330

CDM-710/L Broadcast Satellite Modem
Appendix E
Example: In the diagram that follows, the (Co+No)/No as 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).
The relationship used to derive the table values is as follows (only simple way for
DVB-S2):
Eb/No=10log (10
10
where:
•
Eb/No and(Co+No)/No
•
Spectral Efficiency
overhead and framing and is shown in Table E-1 and Table E-2.
This equation applies to DVB-S and DVB-DSNG, or use the traditional
relationship:
Eb/No=10log (10
10
where:
•
Eb/No and(Co+No)/No
•
FEC Code Rate(Composite)
bits/symbol
•
• Pay close attention to the sign of the middle term.
((Co+No)/No)/10)
-1)–10log
are expressed in dB, and
includes the modulation type, code rate,
((Co+No)/No)/10)
-1)-10log
(bits/symbol)
are expressed in dB;
=3/4*(188/204), 7/8*(188/204), etc.
=2 for QPSK, 3 for 8-PSK, 4 for 16-QAM;
E–2
MN/CDM710.IOM
(Spectral Efficiency)
10
(FEC Code Rate)10log
10
Revision 12
10