Televes DVB-S2 COFDM - Manual (Page 20)

DVBS2 - COFDM / COFDM CI
20
7. - Controlling the Device
This version of the DVBS2-COFDM (CI) T0X allows
configuration and monitoring via a PC, both locally
and remotely.
a. Local control
You need to have the TSuite software package
(version v2.1.4.x32 or higher), as well as a special
cable (provided with the programme) that
connects a PC serial port to the DVBS2-COFDM (CI)
T0X “PRGM” connector.
The programme can be used to set up and read all
the operating parameters, as well as to monitor the
correct operation of the device.
b. Remote control
It is necessary to have a Headend Control module
(ref. 555901) that includes the programme
mentioned above, and the corresponding modem
connected to a phone line.
Once the communication with the headend
control has been established, all the controllable
devices that have been installed in the headend
can be accessed. In this case it is essential that each
element be programmed with a different device
address between 1 and 254.
In short, the higher and further to the left the DVB-
T mode selected is, the more powerful this mode
will be in terms of information service output
(Mbits/sg).
On the other hand, the lower and further to the
right the DVB- T mode selected is, the more robust
this mode will be in terms of interferences which
could affect the signal.
The terrestrial transmission channel (transmission
aerial - terrestrial atmosphere – receiving aerial) is
very complex, with numerous interferences that
can potentially affect the DVB-T signal.
Due to this, in Spain, the DVB- T signal is generally
disseminated with the following features:
(1) Type of modulation: 64QAM
(2) Level of protection against Errors: 2/3
(3) Level of protection against echoes: 1/4
If one looks at the previous chart, one can see that
the information service output of the DVB-T mode
is 19.91 Mbits/s.
In our case, the DVB-T signal generated by the
DVBS2-COFDM (CI) transmodulator, is not going to
be transmitted through the terrestrial transmission
channel, but through a channel that is generally
much more benign: the distribution network of
the building.
NOTE: The better the quality of the building´s
distribution network, the better the transmission
channel will be when transmitting signals.
Given that our transmission channel is better, we
can use the DVBS2-COFDM (CI) transmodulator,
by selecting a higher DVB-T output mode than
that used by terrestrial channels to disseminate.
This will have a greater information service output
(Mbits/s) and will therefore enable us to include a
greater number of TV and Radio
services.
Therefore, when setting up the DVBS2- COFDM (CI)
transmodulators, one should follow a procedure
such as the one below:
1 - Select one of the stronger DVB-T output
modes.
E.g. 64QAM-5/6 with GI=1/32, information
service output of 30.16 Mbits/s.
2 - Check the quality of the signal received at
various points within the building.
If the signal quality is good, the technician can
consider using an even stronger DVB-T mode,
in other words, one with a greater information
service output. On the other hand, in cases where
the signal quality is insufficient, they must consider
using a more robust DVB-T mode.
In most cases, the distribution network within
the building should support those DVB-T modes
that have a lower protection level against echoes.
Therefore, if a more robust mode is necessary,
one should first try using, one at a time, greater
protection levels against errors.