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Re: AMSAT has a SECRET!



Yes, given that the satellite cost millions and millions of dollars,
it makes a lot of sense to spend a few hundred K $$$ extra to get a
bullet-proof downlink.

But the dish is definitely 11 meters.  Go look at the pictures.
Here is the main page for the ground system stuff:
http://hessi.ssl.berkeley.edu/ground_systems/station.html

Doug
NA1DB

At 12:59 PM 6/4/01 , you wrote:
> >I stumbled across the web pages for the soon-to-be-launched HESSI satellite.
> >This satellite will be in a 600 km high orbit, and will have a 5-watt
> >transmitter on 2215 MHz, with a 5 MBPS data rate.  To receive this, their 
> >ground station needs a 11-meter dish!  Check out:
> >http://hessi.ssl.berkeley.edu/ground_systems/Gif/antenna_install_79.jpg
> >This antenna is speced to point with 0.05 degrees of accuracy,
>  Their 5 (*not* 11) meter dish has a
>specified G/T of +16.2 dB/K. So the received C/No would be
>
>+7dBw - 165.4dB + 16.2 dB/K - -228.6 dbJ/K = 86.4 dB-Hz.

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