Promax Promax TV EXPLORER HD ISDB-Tb, Manual

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USER’S MANUAL. TV EXPLORER HD ISDB-T/T
B
11/2010 Page 57
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In a digital reception system for cable signals, after the QAM Annex-B
demodulator an error correction method called Reed-Solomon is applied (see following
Figure). Obviously, the error rate after the corrector is lower to the error rate at the QAM
Annex-B decoder output. This is the reason because this screen provides the BER
measurement before FEC (Forward Error Correction).
TUNER A/D
J.83/B QAM
DEMOD.
REED-SOLOMON
BER before FEC
Figure 31.- Digital reception system via cable.
The BER measurement is provided in scientific notation (i.e. 1.0 E-8 means
1.0 x 10
-8
that is to say one wrong bit of every 100000000) and through an analogue bar
(as its length is smaller the signal quality will be better). The analogue representation is
done on a logarithmic scale (not linear).
5.14.7.2 DVB-C signals
Once determined the parameters of QAM signal, it will be possible to measure
BER , press the [12] key until the BER measurement display appears.
In the BER measurement mode, the monitor will show a display like the following
one:
Figure 32 .- DVB-C ( QAM ) signals BER measurement screen.
The BER measurement before error correction is shown: BER before FEC
(Forward Error Correction).