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Re: ATV from Space?



Dave Hartzell wrote:

> Why not start out with a simpler FSTV downlink of real-time video of 
> the Earth?
>
> It might get boring after a while, but it would be a good opportunity 
> to learn about link characteristics, etc for FSTV in space...
>
> Cloud cover and geography could be viewed, and maybe ham information 
> could be broadcast in-band via Closed Caption! ;-)


I think this graph would apply...

http://www.hamtv.com/giffiles/DXgraph1.jpg

I checked ISS and it was about 350km up. When it's at horizon it's going 
to be
pretty far away. According to this, at 300 miles with 100 watts signal, 
looks like
around 28DB of gain? That's a lot of power and antenna for 70cm. That 
436CP42
has 16.8db -- and that's pretty big already. Maybe with like 4 of these 
suckers, and 200 watts
on the transmit and some gain on the transmit antenna side it could 
work? That
is a lot of stuff though.

(I always make some horrible mistake when I work this stuff out, but I 
think this
is right.)

Imo, would be cool to have camera on the ISS and see astronauts walking 
around or chatting
or something. I don't see how the numbers add up for 70cm though.
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