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Re: BBQ Dish Gain

Tom is absolutely correct.  Rather than debating the numbers why not
actually measure what you have.  By comparing Sun noise and ground noise to
the quiet sky you can determine both your system gain and effective system
NF.  This also give you a very effective way to find out which feed best
matches your chosen dish.

The SetiLeague has a good web page to get you started.



----- Original Message -----
From: "Tom Clark, W3IWI" <w3iwi@toad.net>
To: <ericrawson@rawsonoptics.com>; <amsat-bb@AMSAT.Org>
Cc: <kn6kc@arrl.net>
Sent: Sunday, March 09, 2003 15:43 PM
Subject: RE: [amsat-bb] BBQ Dish Gain

> In terms of what real counts -- the received S/N ratio -- it is really the
> ratio of Gain to System Temperature (called G/T) the matters. If some of
> "lost" illumination leaks onto the warm earth because the feed is not
> right, then you take a double hit -- Gain goes down and Tsys goes up. This
> is the reason that offset feeds work so well: much of the illumination
> "spillover" loss hits cold sky instead of warm earth.
> 73, Tom

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