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TELE-audiovision International — The World‘s Leading Digital TV Industry Publication

— 05-06/2015


Optical System

Fiber optics are used more

and more often when there

is a need to distribute satel-

lite signals to a large number

of receivers. That’s because

fiber optic cables attenuate

signal much less than clas-

sical coaxial cables and add

very little noise to the signal

they convey. It is relatively

easy to find components for

such a system when you

want to distribute the signal

from one chosen satellite.

But if you want to deliver sig-

nals to a high number of re-

ceivers from not one but four

satellites plus a signal from a

terrestrial antenna, the job is

no longer that easy. Time for

Tekniksat Electronics! They

have developed an exten-

sive product portfolio built

around fiber optic distribu-

tion components.

For this test report we de-

cided to build a simple dis-

tribution system and used

these components made by

Tekniksat: TPF 41-2 Opti-

cal Transmitter, TFS 1/32 FC

Splitter and TFM 41/10 C Op-

tical Multiswitch.

The TPF 41-2 Optical

Transmitter is in fact a rack

mounted signal amplifier

and converter. Its job is to

amplify and convert satel-

lite signals coming from 4

different LNBs and 1 terres-

trial input to a single optical

signal. Concerning LNBs, you

can use either Quattro or

Quad LNBs. So, it is easy to

figure out that the TPF 41-2

has 4 x 4 = 16 satellite in-

puts designated with HH, HV,

LH and LV symbols. The 17th

input is for the terrestrial

antenna input, which can be

either an over-the-air recep-

tion like DVB-T/T2 or for con-

necting to a cable system

(DVB-C). Of course, that’s

because terrestrial and cable

TV share the same frequen-

cy band: 47-870 MHz. In this

test report we decided for

connecting the system to a

terrestrial antenna.

The unit provides 23 dB

gain for the satellite signals

and 15 dB gain for the ter-

restrial signal. You can ad-

just each input with a mul-

titurn potentiometer and the

adjustment range is 15 dB.

If needed, you can switch off

the LNB power. If you do not,

then the four LNBs will get

the suitable 13 or 18 V volt-

age for polarization switching

and 22 kHz signal for band

switching from the TPF 41-2.

The TPF 41-2 Optical Trans-

mitter is well finished off and

looks robust and solid. A

cooling fan installed on the

Optical Distribution System

sands of meters and/or split

it to many branches.

In our test we used a 1-to-

32 splitter. Namely it was the

TFS 1/32 FC. The ideal 1-to-

32 splitter would produce at

each output a 1/32 fraction

of the input power. Unfortu-

nately, every practical device

has some additional losses.

In case of the TFS 1/32 FC

those additional losses are

really marginal. The inser-

tion loss is only 16.8 dB

(vs. theoretical 15.05dB).

The splitter itself is a rather

rear panel helps preventing

overheating although during

our tests we did not notice

excessive warming. It may

be useful when the unit is in-

stalled in a cramped 19 inch

cabinet though.

The TPF 41-2 has one SC/

APC optical port and gener-

ates a strong output signal:

4 mW (6dBm). This is the

entry point for the fiber optic

network. With such a strong

signal you can transfer the

signal to very remote loca-

tions: hundreds if not thou-

Optical Distribution System

Perfect to feed hundreds of subscribers with

identical quality signals