TV EXPLORER HD+ manual - Promax

EnglishUSER’S MANUAL. TV EXPLORER HD +In a digital reception system for satellite signals (DVB-S), after the QPSK decodertwo different correction methods are applied (see following Figure). Obviously, each timewe apply an error corrector to a digital signal, the error rate changes, therefore if wemeasure in a digital satellite television system, for example, the error rate at the output ofthe QPSK demodulator, at the output of the Viterbi decoder, and at the output of theReed-Solomon decoder, we obtain nothing more than different error rates. This is thereason because the BER measurement is provided before FEC, after Viterbi (VBER).Figure 39.- Digital reception system via satellite. (DVB-S)Figure 40.- DVB-S (QPSK) signals VBER measurement screen.In a digital reception system for satellite signals (DVB-S2), after the QPSKdecoder other two different correction methods are applied (see following Figure). In thiscase, as the previous one, each time we apply an error corrector to a digital signal, theerror rate changes, therefore if we measure in a digital satellite television system, forexample, the error rate at the output of the QPSK/8PSK demodulator, at the output ofthe Low Density Parity Check (LDPC) decoder, and at the output of the BCH decoder,we obtain nothing more than different error rates. This is the reason because the BERmeasurement is provided after LDPC (LBER). It also shows the amount of packet errors(PER), that is, the amount of packets receiving during the measurement time, which arenot correctable by the demodulator (WP).Figure 41.- Digital reception system via satellite. (DVB-S2).01/2011 Page 61