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Re: AMSAT-BB On phased arrays with azimuth and elevation beam forming



Sorry, but it is crystal-controlled.

Well, I recall thinking about trying to send enough power at 147.995 to
get a detectable signal on the output.  Never tried it, though (it had
a crystal filter in the i.f., so the out-of-band loss would be fairly
high (the bandwidth was 50 kHz, as I recall).  A few folks talked about
some "slightly out-of-band" tests, but I don't know how that turned
out, since I changed jobs before the bird was launched.

We put a diode network into the antenna feed to try to generate a bit
of third-harmonic for an experiment for a researcher named Owen
Garriott, a name which didn't mean anything to me at the time.

Around the same time, there were rumors going around our lab about some
discussions between Hughes management and the ARRL about some
possibilities.  Nothing happened there, of course.

Bob


On Tue, Aug 29, 2000 at 11:01:24PM -0400, Frank Grossman wrote:
> Hey Bob...
> 
> I don't suppose that old ATS-1 repeater can somehow be reprogrammed or
> retuned to operate in the amateur two meter band?  -s-  It would sure be a
> hoot to have a quasi-geosynchronous FM repeater!
> 
> Well, we can dream, right!
> 
> Frank
> wb2bxo@amsat.org
> 
> 
> > Date: Tue, 29 Aug 2000 12:18:26 -0700
> > From: Bob Nielsen <nielsen@oz.net>
> > Subject: Re: [amsat-bb] On phased arrays with azimuth and elevation beam
> forming
> >
> > The number of bits required is a function of the beamwidth, which is a
> > function of the length and width of the array, so it is hard to
> > generalize.
> >
> > Actually the satellite system I was describing used analog phase
> > shifters with one varactor for each transmitter and receiver (there
> > were 8 each, one per dipole).  The drive waveforms were somewhat
> > complex as I recall.  I no longer have any of the documentation,
> > unfortunately and the details have faded a bit with time....
> >
> > I recall there was an article about the system in QST by KH6IJ, who was
> > involved in some educational applications using ATS-1 and/or 3 (ATS-3
> > had a system similar to ATS-1, but used a linear translator).
> >
> > The last I heard (several years ago), ATS-1's repeater system was still
> > functional and had occasionally been turned on for testing (the array
> > defaults to omnidirectional in the absence of a de-spin signal).  The
> > satellite had long before lost all its fuel and was drifting quite a
> > bit.
> >
> > Bob
> >
> > On Tue, Aug 29, 2000 at 02:45:07PM -0400, Bob Bruninga wrote:
> > > Bob Nielsen wrote.... about ... phased arrays to create a steerable
> "beam"
> > >
> > > > It could be done at VHF with L-C phase shifters using varactors as
> > > > variable capacitors.
> > >
> > > Wow, I would love to see the analysis and background in an article!
> Would
> > > 3 bits of precision be sufficient? (3 varactors)  That would give +/-
> > > phase increments of say 22 degrees between +/- 45 deg?
> > >
> > > Can I assume that +/- 90 deg would give you a beam spread of +/- 45 deg?
> > > I guess then that for my roof pointed south, I would need +/- 180 phase
> > > shifts to get from Moon rise to moon set?  Probably would take 4 bits of
> > > precision?
> >
> > - --
> > Bob Nielsen, N7XY                          nielsen@oz.net
> > Bainbridge Island, WA                      http://www.oz.net/~nielsen
> >
> > - ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> > ------------------------------
> >
> 

-- 
Bob Nielsen, N7XY                          nielsen@oz.net
Bainbridge Island, WA                      http://www.oz.net/~nielsen
 
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