Dvb-S Signals - Promax PRODIG-5 Manual Del Usuario

5.14.5.3

DVB-S signals

Once determined the parameters of QPSK signal, it will be possible to measure
BER. Following is shown the BER measurement before the error corrections: BER
before the FEC: CBER.
MPEG-2
Figure 31.- Screen of CBER measurement (QPSK signals).
In a digital reception system for satellite signals, after the QPSK decoder two
different correction methods are applied (see following Figure). Obviously, each time we
apply an error corrector to a digital signal, the error rate changes, therefore if we
measure in a digital satellite television system, for example, the error rate at the output
of the QPSK demodulator, at the output of the Viterbi decoder, and at the output of the
Reed-Solomon decoder, we obtain nothing more than different error rates. This is the
reason because the BER measurement is provided before FEC, after Viterbi (VBER).
Figure 32.- Digital reception system via satellite.
Page 56
-6 -5 -4
FREQ: 1781.94 MHz
5037 kHz
DL-Ku: 12382.0 MHz
CH: 99 MHz
USER'S MANUAL. PRODIG-5
-3 -2 -1
C/N: 0.2
POWER: 51.5 dBµV
MER: 10.9
» CBER: 9.7E-4
VBER:
5.2E-8
dB
dB
11/2013