Promax US TV EXPLORER 2 User Manual página 67

USER'S MANUAL. US TV EXPLORER II
-6
FREQ:
DL-Ku:
CH:
MPEG-2 TS
Figure 35.- 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 (CBER) and after
Viterbi (VBER).
Figure 36.- Digital reception system via satellite. (DVB-S)
-8
FREC:
DL-Ku:
CAN:
MPEG-2 TS
Figure 37.- DVB-S (QPSK) signals VBER measurement screen.
10/2007
-5 -4 -3 -2
1781.94 MHz C/N: 0.2
5037 kHz POWER: 51.5
12382.0 MHz MER: 10.9
99 » CBER: 9.7E-4
VBER: 5.2E-8
-7 -6 -5 QEF
1781.94 MHz C/N: 0.2
5037 kHz POTEN.: 51.5
12382.0 MHz MER: 10.9
99 CBER: 9.7E-4
5.2E-8
» VBER:
-1
dB
dBµV
dB
-3
dB
dBµV
dB
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