Comtech EF Data CDM-750, Installation And Operation Manual

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CDM-750 Advanced High-Speed Trunking Modem Revision 2
Appendix E MN-CDM750
E–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 Es/No of approximately 2.8 dB (DVB ‐ S2).
The relationship used to derive the table values (the only simple way for DVB ‐ S2) is as follows:
Es/No = C/N = 10log
10
(10
((Co + No)/ 10)
-1) – 10log
10
(Spectral Efficiency)
where:
•
Es/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 E ‐ 1 and
•
Table
E-2
.