axing SKM 40-00M Betriebsanleitung Seite 78

Operation instructions | SKM 40-00M | SKM 40-04M | SKM 80-00M
We recommend you to set the maximal fill level to 90%.
If the current fill level exceeds the maximal fill level, it may cause image disturbances, e.g. mosaic images.
If the net data rate of the signal exceeds the net data rate of the output channel, the modulator overflows. This
overflow leads to disturbances. If the modulator overflows, the status LED on the front side of the device lights
in red.
Filtering the programmes (see 3.4on page 20) 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
QPSK
16-QAM
64-QAM
30
Code rate
1/4
1/2 4.976
2/3 6.635
3/4 7.465
5/6 8.294
7/8 8.709
1/2 9.953
2/3 13.271
3/4 14.929
5/6 16.588
7/8 17.418
1/2 14.929
2/3 19.906
3/4 22.394
5/6 24.882
7/8 26.126
2020-02-23 | Technical improvements, changes in design, printing- and other errors expected.
Guard interval
1/8 1/16
5.529 5.855
7.373 7.806
8.294 8.782
9.216 9.758
9.676 10.246
11.059 11.709
14.745 15.612
16.588 17.564
18.431 19.516
19.353 20.491
16.588 17.564
22.118 23.419
24.882 26.346
27.647 29.273
29.029 30.737
1/32
6.032
8.043
9.048
10.053
10.556
12.064
16.086
18.096
20.107
21.112
18.096
24.128
27.144
30.16
31.668