Background Image
Previous Page  18 / 164 Next Page
Show Menu
Previous Page 18 / 164 Next Page
Page Background


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

— 05-06/2015

Optical Multiswitch before

it reached a subscriber out-

put. All the gain settings in

the TPF 41-2 and TFM 41/10

C where set to maximum. It

proves that the overall sys-

tem gain is very precisely

calculated and is exactly

as needed for a 1:32 split.

if you built a system for a

lower number of receivers

you would need fewer split-

ting (say, 1:8) and then you

would have to reduce the

gain of the Tekniksat devices

to avoid over driving sub-

scriber receivers.

The second very important

characteristics of the distri-

bution system is its “quiet-

ness” or, in other words, the

measure how much it spoils

the signal-to-noise param-

eter. Taking into account

that we deal hear with two

signal conversions: electri-

cal to optical and optical to

electrical and additionally

the signal is split firstly in the

optical splitter and secondly

in the final multiswitch, one

could expect a significant

decrease in Modulation Error

Ratio (MER). But, no! Look at

the second graph. Although

there is a small degradation

of signal quality especially in

the lower sub band, the dif-

ference between input and

output is surprisingly low.

You can be pretty sure that if

you have a good signal from

the LNBs, almost equally

good signal will reach each of

the maximal possible num-

ber of 320 receivers.

And that is what we call the

“Power of light”. It is so easy

to achieve such good results

with fiber optic cables when

compared with traditional

electrical splitting.

After so good results with

satellite signals we wanted

to check the terrestrial path.

Our measurements revealed

that the output signal was

stronger by about 15-20 dB

with respect to the input sig-

nal and that signal-to-noise

ratio was again decreased