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Re: Re: Flight Opportunity



On Thu, 22 Oct 1998, Richard W L Limebear wrote:

> Stephan Greene writes:
> 
> snip
> > Quite a lot can be done in that volume, although 2 W will limit the TX
> > power.
> 
> 2W from space can be LOUD. Say 1.5W for tx and the rest for the other

Assuming 50% TX efficiency, that gives us about 0.75W at the TX output. 
Considering AO-27 usually runs 0.5 W (-1.7 dB) 

> bits - should be plenty. Remember, someone else will be doing the command/
> control, attitude control, etc. KISS principle will work fine here; don't
> (shock, horror) put a computer in it.

I was specifically thinking of the "TSFR" tray/module in A0-27.  It
contains modems, control circuitry allowing selection of different combos
of modems and signal sources/outputs, *and* the amateur payload.  While
the main flight computer 2 trays down is required in data modes, it just
toggles different settings in voice mode (AO-27's normal operation).
While the stated requirement is about 1/2 the volume available on AO-27,
components have gotten smaller and I think there was a fair amount of
unused volume.

> Big question: what antennas will they allow to be mounted outside ?

Yep.  If the spacecraft has some nadir-pointing ability, the antenna
pattern can have some directivity; even 3dB from a earth-pointing platform
would provide significant improvement vs. AO-27.  But even a 1/4 whip
would work.

Of course there needs to be a mission defined before someone can start
stuffing a box with hardware and software, even on paper.  Would a
flexible "rudak"-style payload fit in the available space and power?
(Assuming the talent and resources to build one exist)  Just an idea.

73  Steve  KA1LM@amsat.org

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