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what dish to capture a geostat. sat shifted of 75 deg long ?
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 |