Fracarro 3DG-2S2-2T, Руководство по эксплуатации

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34
English
DVB-T
64-QAM
Guard interval
1/4 1/8 1/16 1/32
FEC
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 30,160
7/8 26,126 29,029 30,737 31,668
DVB-C
m-QAM
16 32 64 128 256
SR
2,0 7,373 9,216 11,059 12,902 14,745
5,1 18,800 23,500 28,200 32,900 37,600
6,0 22,118 27,647 33,176 38,706 44,235
6,9 25,435 31,794 38,153 44,512 50,871
The bitrates are expressed in Mbps, the symbol rate in the DVB-C standard is expressed in
MSps.
For mux set in the DVB-T standard: constellation 64-QAM, FEC 7/8, guard interval 1/32,
guarantees a bitrate of 31.668Mbps.
For mux set in DVB-C: constellation 256 QAM and symbol rate 6900 MSps guarantees a
bitrate of 50.871 Mbps.
As the tables above show, the default settings guarantee greater available bandwidth.
Note that, with the DVB-C standard, the symbol rate determines the bandwidth: with 6900
MSps, the mux occupies 8 MHz, with 6000 MSps 7 MHZ and with 5100 MSps 6 MHz, therefore
in the case of a number of channels, attention must be made when setting the muxes to ensure
they do not overlap each other.
The module must be programmed so that it is an insensitive as possible to an increase in bitrate
of one or more programs included in the output multiplex. The output program multiplex is
organised according to a priority queue Last in First Out: the last program inserted in the queue
will be the first out if the maximum available bitrate limit is exceeded.
The removed program will automatically return to the list once the total bitrate has fallen within
the maximum bitrate limit. The program position in the list can be changed at any time in the
program menu.
In the case of an overflow alarm, the module continues to work correctly by eliminating one or
more programs beginning from the one with the lowest priority (therefore the first program that
was inserted has the highest protection).
Moreover, an innovative overflow algorithm enables automatically returning the eliminated
program to the list if, at a later moment, the available band allows this.
This can be done as the channel is not removed from the output list just the PID (which can then
be reinstated).
It is fundamental to separate programming into two types according to the broadcast method for