"Thierry" - wrote in message ...
Hi,

A question : how weak is a geostationnary satellite signal at the edge ?
(case study)

Imagine a geostationnary TV satellite like AMC-6 located over NY or so (72
deg W) with a signal 50 dB in area 500 km wide, decreasing down to 30 dB a
few hundreds miles offshore and thus very weak in Europe (10 dB ?)
The satellite transmits two signals : its NTSC video (vertically
polarized)
near 3.88 GHz and an audio at 6.8 MHz FM mode (monaural), standard specs
used e.g. by NASA TV.

Is there a way to capture its signals from Europe (say ON) using a 2 to 4m
wide type TVRO or Quorum dish (with preamp, NTSC/PAL converter, etc)
knowing
that its beam is quite narrow and the signal very weak ?
In addition a beam cut on 6.8 MHz 'd be used to capture its FM signal on
HF,
the satellite being not to high above the horizon ... (supposition)
NB. In this example the longitude difference is 50-75 degrees !!

Theoretically, is it possible to built such a system being so far from the
satellite and the satellite being so low over the horizon ?
or the beamwidth of the satellite dish does not permit receiving at such
longitude differences ?

Or say in other words, has an european ham already tried to capture US
geostat satellites successfully ? and using what kind of system (RX and
antenna diam.)
or conversely, has an US ham succeeded to capture signal from an european
geostat satellite (Meteosat...) ?

What should be the minimum antenna specs to get a "good" receive
(diameter,
preamp gain, without or without downconverter and then rx qrg, longitude
difference max., signal strength at receive on 2m and 4m dish...)

I think that it is possible with a dish 2m, but I 'd like a confirmation.

Thanks in advance

Thierry, ON4SKY
http://www.astrosurf.com/lombry

Do the math- what is the minimum dish size required to receive the signal
in the 50dB contour? If your contour is 10dB- you are 40 dB down. Dish gain
goes up 6dB each time you double the diameter- so you need a dsih 128X the
diameter of the 50dB contour dish. to yield the same pix quality.

Dale W4OP