Promax TV EXPLORER HD Manual De Usuario página 151

USER'S MANUAL. TV EXPLORER HD
Figure 26.- DVB-T/H (COFDM) signals CBER measurement screen.
In a reception system of terrestrial digital signal, after the COFDM decoder two
error correction methods are applied. Obviously, each time we apply an error corrector to
the digital signal, the error rate changes, therefore if we measure the error rate at the
output of the COFDM 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. The
TV EXPLORER HD provides the BER after Viterbi (VBER).
TUNER A/D
Figure 27.- COFDM reception system.
Figure 28.- DVB-T/H (COFDM) signals VBER measurement screen.
The BER measurement is provided in scientific notation (i.e. 1.0 E-7 means
-7
1.0x10 , that is to say 1.0 average value of wrong bits of each 10000000) and through a
graphic bar (as its length is smaller the signal quality will be better). The analogue
representation is done on a logarithmic scale (not linear), that is to say, the bar divisions
correspond to the exponent of the measurement.
11/2009
BER before FEC,
MER BER after Viterbi
COFDM
VITERBI
DEMOD.
RED-SOLOMON
Page 53