UNAOHM
54
EP2500 (Rev. 0)
For DVB-S, QPSK with BW=33MHz, Rs=27.5 M symb/sec obtains:
Eb/No=C/N – 10 log
[
(27.5*2)/33
]
Eb/No=C/N-2.2
Figure 27
CH BER/pViterbi BER comparison in respect of Eb/No variations for a given BER
The instrument supplies both BER parameters described but actually the only parameter that is truly
useful to the installer is the CH BER.
Indicatively, for a good installation that should withstand variations throughout long periods of time
(aging of components, thermal shifts) and those provoked by changes in meteorological conditions
(weakening due to snow, rain) the initial conditions to be obtained are summarized, along general lines,
in the following table:
Measurement carried out on
CH BER (pre Viterbi BER)
LNB output
or
Headend output
Worst user’s socket
from 1E-5 (1 error out of 100000)
to 1E-4 (1 error out of 10000)
better than 1E-3 (1 error out of 1000)
Table 2
