Frequency Plan - Alcad 912-TQ Serie Manual De Instalación Y Programación

24 - ENG
41- F-connectors
42- List of technical characteristics
3.

FREQUENCY PLAN

TQ transmodulators generate DVB-C cable signals from DVB-S satellite
signals. Such transformation implies a change in modulation from QPSK
to QAM, a band change from IF to RF and a change in bandwidth. This
makes it possible to distribute the selected DVB-S satellite transponders
(QPSK modulation) through one single coaxial cable, according to the
DVB-C standard (QAM modulation) in the 47 to 862MHz band.
The input frequency of the transmodulators must be equal to the IF of the
selected satellite transponders.
The output frequency must be set to any value between 47 and 862 MHZ,
in 1MHz increments, by programming the centre frequency and ensuring
that the bandwidth to be occupied by the QAM signal is free.
In order to program the output frequencies, it is recommended to use a
frequency plan with 8MHz channels. Among the possible output bands,
the S band should preferably be used, since it is rarely used in existing
installations. The standard frequency plan is attached as an Appendix to
this Manual.
MHz 122
BW 7.0
In the event of setting up a frequency plan in the VHF band or in the low
S band, which would combine QAM channels with other channels, it
might be necessary to allocate a 7MHz bandwidth to the QAM channels.
As a result, the QAM frequency plan will coincide with the channels of
most standards. In order to combine QAM channels with other channels,
it will be enough to refrain from allocating QAM channels to already
occupied channels and to check that the QAM signals occupy a
bandwidth inferior to the assigned one.
Installation and programming manual
130 138
7.9
8 MHz 8 MHz
Fig. 5 - Standard frequency plan
146
4.3
2.0
8 MHz
858
7.9