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Re: AO-40 and future sats.



Each satellite needs large enough solar panels to power the transmitter. You
are correct that a microwave-only satellite would be lighter and cheaper as
the transmitter power output required would be lower. Background noise at
2400 MHz is 250 times lower than at 144 MHz if your antenna is pointing at
the sky. A digital downlink would also reduce power requirements.

However, the need to constantly adjust the orbit to make it stay synchronous
increases the cost and complexity beyond that of AO-40. LEOs are cheap
because they reduce the transmitter power required for the downlink by a
factor of 100 and eliminate the need for a heavy rocket engine and fuel.

73,

John
KD6OZH

----- Original Message -----
From: "Frederick M. Spinner" <fspinner@hotmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, 18 December 2000 02:35 UTC
Subject: [amsat-bb] AO-40 and future sats.


> Even if AO-40 doesn't come back-- I've done enough experimenting and
> tinkering with my station and microwave equipment to be happy.
> I guess thats why I am not much of a DXer.. I derive my joy in ham radio
> from building the station up.
>
> Anyway.. I have and probably will still disagree with the sat community
> about geosync sats.  If there were a way to put up three small microwave
> sats, and maybe have two or three ground stations cross link all of them
> together, we would have the ultimate setup.. worldwide coverage-- small
> antennas-- no rotors.  The southern hemisphere would not get shafted
either
> in that scenario.
>
> Is it possible to put three small sats in a high orbit with a propultion
> system, and keep it light enough to be a cheap launch?
> I dunno-- maybe one of the aerospace guys can prove that I'm an idiot.
> But from a communications perspective it seems like a good idea.
>
> I'd not completely panic yet.. Remember what was done to DO-17 and
> KO-23.. sometimes the herculean efforts of the ground stations can
> pay off.  I seem to remember that one of the big EME arrays recovered
DO-17
> once.
>
> My only concern really is will the batteries hold out until 21 DEC or
> 25 DEC?
>
> Fred W0FMS


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