Operation instructions | SKT 40-00 | SKT 80-00 | 8PSK/QPSK | COFDM Quattro/Octo Module
14
2016-01-11 | © AXING AG Switzerland | Subject to change in design and type; errors and misprints reserved
100% modulator fill level correspond to the maximal net data rate of the output channel. The maximal net
data rate depends on the chosen settings. The bandwidth, the modulation, the code rate and the guard interval
affect the net data rate. COFDM modulated channels allow net data rates from 4.98 up to 31.67 Mbit/s
(typically 24).
Table 1: Net data rate in the 8 MHz channel:
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
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 programs (see chapter 3, section 3.1) reduces the net data rate of the input signal. Subsequently,
the net data rate of the output signal is also reduced.
The data rates of the programs are not constant. They are dynamically changed by the sender. These
fluctuations can be noticed in the fill level.
To avoid an overflow, we recommend that you don't let the maximal fill level exceed 90%.
