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Operation instructions | SKT 40-0x | SKT 80-0x | SKT 40-0xM | SKT 80-0xM
24 2017-01-26 | Technical changes, design modifications, errors and misprints are subject to change without prior notice.
Filtering the programmes (see 3.4 on page 18) reduces the net data rate of the input signal. Subsequently, the
net data rate of the output signal is also reduced.
The data rate of the DVB-T channel depends furthermore on the chosen channel bandwidth (7 or 8 MHz), on
the set error correction rate (FEC) and the modulation rate (QPSK, QAM16, QAM64) of the modulator.
If the displayed data rate exceeds 90%, there are different possibilities to change it:
Change to a channel with a bandwidth of 8 MHz if a 7 MHz channel was selected previously.
Raise the modulation rate to 64 QAM. QPSK corresponds to the lowest, the QAM64 setting to the highest
output data rate.
Set the forward error correction to 7/8. With this setting, the data rate is increased, but the error correction
is lower. A lower error correction requires a better transmission quality from the antenna network.
Set the guard interval to 1/32. This shorter guard interval allows you to reach greater data rates.
Reduce the number of selected programmes in the channel list.
COFDM modulated channels allow net data rates from 4.98 up to 31.67 Mbit/s (typically 24).
Modulation
Code rate
Guard interval
1/4 1/8
1/16
1/32
QPSK
1/2
4.976 5.529 5.855 6.032
2/3
6.635 7.373 7.806 8.043
3/4
7.465 8.294 8.782 9.048
5/6
8.294 9.216 9.758 10.053
7/8
8.709 9.676 10.246 10.556
16-QAM
1/2
9.953 11.059 11.709 12.064
2/3
13.271 14.745 15.612 16.086
3/4
14.929 16.588 17.564 18.096
5/6
16.588 18.431 19.516 20.107
7/8
17.418 19.353 20.491 21.112
64-QAM
1/2
14.929 16.588 17.564 18.096
2/3
19.906 22.118 23.419 24.128
3/4
22.394 24.882 26.346 27.144
5/6
24.882 27.647 29.273 30.16
7/8
26.126 29.029 30.737 31.668
3.5.3.
Chosen programmes
The programme table
Selected Programs
shows the programmes that were activated in phase 2 and that have
been selected in the Cross Multiplex.