Itu-T J.83/B Signals - Promax TV EXPLORER HD ATSC Manual De Instrucciones

5.14.7.1

ITU-T J.83/B signals

Once determined the parameters of QAM Annex-B signal, it will be possible to
measure BER, press the
In the BER measurement mode, the monitor will show a display like the following
one:
Figure 31.- Screen of BER measurement of QAM Annex-B signals.
The BER measurement before error correction is shown: BER before FEC
(Forward Error Correction).
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
The BER measurement is provided in scientific notation (i.e. 1.0 E-5 means
-5
1.0x10 that is to say one wrong bit of every 100000) 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).
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[12] key until the BER measurement display appears.
J.83/B QAM
A/D
DEMOD.
Figure 32.- Digital reception system via cable.
USER'S MANUAL. TV EXPLORER
BER before FEC
REED-SOLOMON
HD ATSC
12/2010