A.3.1 Range Of Data Rates - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710/L Broadcast Satellite Modem
Appendix A
A.3.1 Range of Data Rates
For the detailed Range of Data Rates see Chapter 2. SPECIFICATIONS.
A.3.2 Eb/No, Es/No Spectral Efficiency and Occupied
Bandwidth
Depending upon the operating mode, the DVB standard uses different modes of
specifying performance with a modem in IF Loop and Additive White Gaussian
Noise (AWGN):
• DVB-S (QPSK with Viterbi and Reed Solomon): BER=2 x 10
(before Reed Solomon) and QEF after Reed Solomon at the specified
Eb/No and includes a modem implementation loss of 0.8 dB and the
noise bandwidth increase due to the outer code (10
Quasi-Error-Free (QEF) corresponds to less than one uncorrected error
event per hour, or BER=10
demultiplexer. This is the error rate most commonly used.
• DVB-DSNG (8PSK and 16QAM with Viterbi and Reed Solomon): Similar
to DVB-S. The modem implementation ranges from 1.0 dB (8PSK 2/3) to
2.1 dB (16QAM 7/8).
• DVB-S2 (QPSK, 8PSK, 16APSK and 32APSK with LDPC and BCH): PER
(packet error rate) = 10
is a theoretical value with perfect carrier recovery and symbol
synchronization, and no modem oscillator phase noise. The manufacturer
decides the implementation margin and specifies performance.
The other difference is the use of PER (packet error rate) based upon a 188
or 204 byte MPEG frame size instead of BER (bit error rate).
Also, note the use of Es/No instead of Eb/No. When links operate at
constant symbol rate, this is a good method for comparing the
performance of different modulation types and code rates. The relation
between the two quantities is given by:
-10 -11
to 10 at the input of an MPEG-2
-7
after LDPC and BCH at the specified Es/No. This
A–3
MN/CDM710.IOM
Revision 12
-4
after Viterbi
188/204=0.36 dB).
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