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TELE-audiovision International — The World‘s Leading Digital TV Industry Publication
— 05-06/2015
—
TELE-audiovision.comstrong the optical signal will
be. Strength of the signal de-
pends on the split ratio and
attenuation of the optic fiber
cables.
After examining all the
products, it was time to build
a test network. We connect-
ed Quad LNBs to the inputs
of TPF 41-2 Optical Trans-
mitter. At the output of the
transmitter we inserted the
TFS 1/32 FC Splitter and
then routed the optical sig-
nal to the input of the TFM
41/10 C Optical Multiswitch.
We knew very well that there
is little point in adding long
fiber cables between the de-
vices because they add very
little attenuation. The main
sources of attenuation in the
optic networks are the split-
ters and junctions if not kept
clean enough.
To evaluate the whole
system rather than its par-
ticular components, we de-
cided to measure and com-
pare the input signal, i.e.
the one coming from LNBs,
to the output signals avail-
able at the trunk and the
subscriber outputs (S1 and
S10) of the TFM 41/10 C Op-
tical Multiswitch. You can see
the results in two graphs:
one showing signal strength
and the other signal quality.
The first graphs answers the
question whether the sys-
tem has enough gain and the
other – to what extent signal
quality suffers when we split
it and deliver it to 320 sub-
scribers.
The output signal strength
was almost the same as in
the input. For some frequen-
cies/subscriber outputs, it
was slightly lower and for
some others slightly higher
than the input. Please re-
member that the signal has
been split 32 times by the
optical switch and then 10
times by the TFM 41/10 C
Fig. 1 Test setup circuit diagram.
tiswitch itself as well as its
power supply leaves noth-
ing to be desired. They are
clearly labeled and it is re-
ally easy to figure out what
should be connected where.
Everything is obvious at the
first look. The TFM 41/10C
has independent gain ad-
justment of every satellite
and terrestrial output (20
dB range). The adjustment
is really needed because it
is not known a priori how