Pagina 229 - TELE-satellite-1205

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229 —
04-05/2012 —
TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
bits. The next block takes care of er-
ror correction and does descrambling
if necessary. Unscrambled and error
corrected BB frames are fed into the
TS processor which turns them into
familiar transport stream packets. The
transport stream is then processed as
in any DVB receiver – a desired TV’s or
radio channel’s TS packets are filtered
out and converted to a HDMI signal or
to analog video and audio in digital-to-
analog converters.
As you can see, the changes in hard-
ware architecture are not so fundamen-
tal but except for introducing them,
also software must be re-written. For
example, today’s receivers assume that
one transponder carries just one trans-
port stream with a given modulation
and FEC ratio. New receivers must be
able to assign more than one transport
stream to one transponder. From the
end user’s perspective, a VCM DVB-S2
transponder is like a few classical DVB-
S2 transponders overlapped one over
another on the same frequency.
If you would like to transmit the VCM
signal as a couple of ordinary CCM sig-
nals, you would need as many classi-
cal transponders as many transport
streams you use. And because such
CCM transponders would have to be
separated in frequency spectrum, the
total bandwidth occupied by them
would be greater than the bandwidth
occupied by one VCM transponder.
That’s the basic advantage of VCM.
The sky seems to be the limit for the
excellence in satellite bandwidth utili-
Fig. 3. Block diagram of VCM compatible
DVB-S2 receiver front end.
1. TELE-satellite first introduced MIS transmission technology (based on VCM) in
TELE-satellite 10-11/2011 in a testreport about the TBS6925 PC card manufactured
by Tenow (
2. ... and then again in a more detailed reception report in TELE-satellite 12-01/2012