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TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
— 09-10/2012
— www.TELE-satellite.com
Transponders lying
close to each other
The reception parameters required
by standard users for their satellite
receivers are average values. In other
words, a transponder with a specified
frequency of 12,600 MHz in general is
not received at precisely this frequency
but rather at an optimum frequency of,
say, 12,598 MHz.
This deviation between nominal and
optimum frequency is caused by the LNB
converter and cables, among others.
Digital satellite receivers are designed
to detect the optimum frequency and
adjust their internal reception param-
eters accordingly.
Strong transponders with sufficient
spacing between each other therefore
hardly cause any problems due to this
impreciseness, but SCPC transponders
with identical or similar symbol rates,
which are close to each other and of
which one transponder is significantly
stronger than the other will cause
receivers to lock the stronger tran-
sponder and ignore the weaker tran-
sponder.
The situation is aggravated by the
fact that only very few receivers for pri-
vate users still have the option of limit-
ing the reception bandwidth, which can
be used to force the receiver to select
its frequency from a very limited range.
The result of all this is that TV stations
can easily hide individual transponders
behind others. If you’re eager to find
out how your receiver at home copes
with this, you can try to receive hori-
zontal channels between 11,619 MHz
and 11,645 MHz on NSS7 at 22° West.
The same is true for channels between
12,507 MHz and 12,655 MHz on EUTEL-
SAT SEASAT 36° East – here too many
receivers will try in vain to lock in a
signal.
As you can see there are many ways
for TV stations to restrict feed reception
for Joe Average even without resorting
to encryption. However, if you’re in the
know you can react accordingly and use
suitable hardware to have your way in
the end. In all TELE-satellite reports you
will find some reference to a receiver’s
SCPC capabilities and an account of how
sensitively its tuner deals with weak sig-
nals.
Diego Rosende from Tenerife, Spain
Ron Roessl from New York, USA
Satheesan Puzhakkara from Thiruvananthapuram, India