Pagina 20 - TELE-satellite-1207

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TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
— 06-07-08/2012
good that GlobalInvacom’s
processor does not require
you to connect to a PC.
GlobalInvacom’s FibreIRS
DTT Processor not only
passes through the desired
TV channels and blocks the
rest of the spectrum but
also amplifies their signal.
The unit is enclosed in a
metal case designed to be
mounted on a wall on two
screws. It has an external
AC/DC plug type adapter.
After unscrewing two screws
and removing the cover, you
get access to the interior of
the processor. Every mod-
ule has an eight position DIP
switch you use to set the de-
sired channel number (from
21 through 69) and to turn
a module on or off. A piece
of foiled paper is attached to
the internal surface of the
cover. It’s a short list of op-
erating instructions, as how
to turn the module on/off
and how to set the channel
number. A few clicks with a
small screwdriver is enough
to do all that setting. A
green LEDs mounted on the
top of each module signals
which one is turned on.
Except for that, every unit
has its own red knob for ad-
justing channel gain. The
nominal adjustment range
is 30 dB. There is also one
slide switch enabling you to
additionally boost the out-
put by about 20 dB (18 dB in
the specs). It adds this extra
gain to all passed through
channels. It may be very
useful when you deal with
very extended or complex
cable networks in which you
expect significant attenua-
For best performance, the
input signal should be above
60 dBµV for DVB-T and not
more than 65 dBµV for DAB.
The output of every channel
should be adjusted optimal-
ly to 70 dBµV if you connect
the GlobalInvacom ODU32
RF-to-light converter to the
processor. If your antenna
has a built in amplifier – no
problem. The DTT Processor
generates 12 V to power the
We started our test with a
real world signal. In our test
location in Western Poland,
two DVB-T multiplexes are
available. They are trans-
mitted on channels E41 and
E45. The signal level was
slightly above 66 dBµV – ex-
actly as needed. As you can
see on the attached screen
shots, the input signal con-
tained some undesired sig-
nals too. These were some
analog TV channels which
are still transmitted as well
as some spurious signals
produced mainly in the an-
tenna amplifier. But the
output of the DTT Proces-
sor was completely free of
them. Only the two digital
channels were left. We ad-
justed the output of every
channel to 70 dbµV without
any problem.
But that’s not all. The car-
rier-to-noise (C/N) param-
eter measured at the output
was better than that at the
input by 12 dB! For example
for E45 channel, it rose from
31.1 dB to 43.7 dB. We were
really astonished because
we had not expected such
significant improvement in
signal quality.
We checked the gain ad-
justment range for every
channel. We got 26 dB ad-
justment range for E41 and
24.5 dB for E45. A little
1. The original input signal picked up by a terrestrial antenna.
There are 2 DVB-T signals at 634 and 666 MHz (channel 41 and 45)
and a lot of unwanted noise.
2. After passing FibreIRS DTT Processor, only the desired DVB-T
signals remain.
3. A test with a white noise generator proves excellent adjacent
channels rejection.
4.Sharp roll-off and flat pass band - splendid frequency characteri-
stics of one of the FibreIRS DTT Processor channel filters.