29
30
31
32
28
27
44
TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine
— 01-02/2014
—
Testing
27. What about joining network signals to the TV signal? I just fitted
two RJ45 splitters at both ends of the 100m network cable reel
and on the input side I connected the Rj-45 cable from the Catline
TVB-02 carrying the TV signal and the network cable coming
from the router. On the other end of the cable reel I attached a
regular network cable which I connected with the RJ-45 input
connector of the Deviser S7000 meter. Also, I connected the special
TVB-01 cable on the other port of the RJ45 splitter. The aerial
connector with the integrated balun was then connected with the
RF connector of the Deviser S7000. As a side note: having such a
meter is great, since you can simultaneously measure TV signals
and verify network, as well.
28. The constellation diagram reveals that there is indeed a slight
modification of the signal quality when networking signals are
carried on the same cable. However, after 100m the constellation is
still pretty good. There was a drop in BER but again, this I could be
partially recover by fine tuning the amplification and tilting at the
TVB-02.
29. After fine-tuning for best results PRE-BER decreased slightly
when the network signal is present in the cable, but most
importantly the POST-BER is perfect and that’s what the error
algorithm is there for, anyway.
30. Time to verify if the network signal is working, too. The Deviser
S7000 allows to ping other networking appliances and I simply
pinged the router. No surprise: all five packets reached the router
without delay or problems and hence 5 responses came back. 0%
packet loss means that indeed one can just add the TV signal to
pin 7 and pin 8 of existing network cables and transport it along.
Please bear in mind that this will not work with 1000MBPS (“Gigabit
LAN”), as in such case all 8 conductors of the network cable are
being used. Also, I tried to see if the TV signal would survive a
network switch. The results were not clear. At some tests I could
indeed pass the signal from the Catline TVB-02 over a network
cable into a switch and then from the switch to the receiver using a
second network cable. However, this did not work always. I believe
that this depends on all other devices connected to the switch: if
one has a gigabit network card, then chances are that it will not
work.
31. Transporting analogue CATV channels is of course possible,
as well. The picture shows the result of the signal received when
amplification and equalisations are not properly setup.
32. After an increase in amplification and increasing the tilt
slightly the result improved clearly. Remember, that this signal just
travelled through 100m of network cable.
