Dominique,
I am also speaking from personal and professional experience with Ku
QPSK MCPC systems. Signal loss through the glass in dB correlates with
the same decrease in Eb/No in digital systems. I am curious what your
location is and what systems you have worked with.
Bob

Dominique Michel wrote:
Le Sat, 05 Aug 2006 15:33:07 GMT,
Bob a écrit :

Are you asking about amateur satellite operation or TV reception via
satellites? Although Dominique’s explanation of digital satellite
signals passing through glass may be explained on paper, it has no merit
in actual use. Some glass has attenuation at C/Ku frequencies but this
purely shows up as signal reduction with associated loss of C/N, BER,
etc in digital systems. Analog and digital satellite reception are
affected the same.
Bob


What I say here is based on personal experience. And it is for TV reception that use phase multiplexing in order to send many different channels on the same frequency. The signal going through a glass is affected in a way that do impossible to receive some channels. A bigger parabol will change nothing, it is just to remove the glass to get all the channels.

You get exactly the same effect if the shape of the parabol is not
perfect (as it can append after a hazard under transportation), it will
work just fine for analog reception but with a digital tuner, some
channels will work when others will not. It is just to change the
parabol to get all the channels. Sometime, the defect with the shape of
the parabol is so little as you see nothing with the eyes, but you
change it against another one from the same model and it just work. I
installed hundreds of parabol antenna, and it was never a problem with
a wholesaler or a manufacturer to change a defective parabol, they know this problem very well.

Dominique

Dominique Michel wrote:
Le Sat, 05 Aug 2006 11:38:23 GMT,
ml a écrit :

hi

thinking about getting into sat's, and have a newbie question

i may only be permitted to put up my antennas on a part of the roof that
would be blocked by a structure(elevator room)

so in 1 compass direction or so to almost straight up i would be blind

question:

so is their a particular compas headding that is best to loose?
It MUST be a direct view from the antenna to the sat. Otherwise is it
just to forget it. With analog reception, the antenna can work very
well through a glass window, or while directing the antenna on a
reflexion (at least if you can afford a high end tuner in this last case),
by but with digital reception, even a tiny glass will cause a
lot of trouble (some channels will just disappear), because the digital technique use phase multiplexing
and the phase of the signal will change in a non linear fashion through
the glass or on a reflexion.

Dominique