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TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine
— 01-02/2014
—
Testing
19. The question is: can you distribute the
same signal over network cable of CAT-5
or CAT-6 quality? Let’s find out! This time
I used our network cable reel, which holds
100m of CAT-6 cable.
20. The spectrum shows the DVB-T2
transponder. Interestingly, the 100m CAT-6
cable reel was able to capture a nearby
LTE transponder, due to the fact that it has
much less cable isolation than a coaxial
cable. However, this did not influence the
test, as this transponder operates at about
810 MHz. Still, this should remind you that
network cable is much less immune to
these situations than regular coaxial cable.
21. The measurement screen shows that
there is more attenuation using the network
cable and I only achieved an LBER value
of 6.2E-05. This however, is perfectly
acceptable for a DVB-T2 signal and the
signal source was not particularly strong to
begin with – as already mentioned I worked
with a DVB-T2 signal with signal power of
-30 dBm at the output of the source.
22. After fine-tuning the equalisation with
the TILT knob on the TVB-02 the results
improved. The LBER is now <1.0E-8, which
means that we actually got a better result
than with the coaxial cable and a simple
amplifier. And no, there is no magic going
on. Despite having a better LBER value
the constellation it is not as clean as with
the coaxial cable distribution. While there
are no modulation errors, one can clearly
see that the “clouds” are not as close
together than before, indicating that the
signal has suffered from being squeezed
into the network cable. Conclusion: you
can be sure to have great results with the
Catline TVB-02 and you have learned that
you should not only use quality cable, but
quality amplifiers, too.
23. And again: here is the proof. Perfect
picture from a DVB-T2 transponder
distributed over in a 100m long network
cable. Amazing!
24. Next I tested transporting a DVB-C
transponder over the 100m long network
cable using the Catline TVB-02. No surprise
at this point, as the spectrum clearly shows
the transponder at the end of the TVB-01
cable attached to the 100m cable reel.
25. Always a concern: having a good
POST-BER. In this case, we have under
1.0E-9, which is the best possible result.
But look closely: even the PRE-BER has
a value of <1.0E-9. This actually provides
a better result than the coaxial cable with
the simple amplifier we used. This proves
that Macab is using a really good amplifier
within the Catline TVB-02.
26. And the constellation diagram shows a
perfect point cloud as if it came from a text
book. These results are incredible. Never
forget that this HF TV signal just went
through 100m of plain CAT-6 cable.
