USER’S MANUAL. TV EXPLORER II/II+
12/2013
Page
57
En
g
lis
h
-6 -5 -4 -3 -2 -1
FREQ:
DL-Ku:
CH:
C/N:
POWER:
MER:
CBER:
VBER:
»
0.2
51.5
10.9
dB
dBµV
dB
MHz
kHz
MHz
1781.94
12382.0
5037
99
9.7E-4
5.2E-8
MPEG-2 TS
Figure 34.-
DVB-S
(
QPSK
) signals
CBER
measurement screen.
In a digital reception system for satellite signals (
DVB-S
), 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 35.-
Digital reception system via satellite. (DVB-S)
-8 -7 -6 -5 QEF -3
FREQ:
DL-Ku:
CH:
C/N:
POWER:
MER:
CBER:
VBER:
»
0.2
51.5
10.9
dB
dBµV
dB
MHz
kHz
MHz
1781.94
12382.0
5037
99
9.7E-4
5.2E-8
MPEG-2 TS
Figure 36.-
DVB-S
(
QPSK
) signals
VBER
measurement screen.
