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Re: Satellite Inquiry



Hi All,
Guess we could have FM on a linear transponder as long as everyone managed
their power. This makes the power budget more demanding as the peak and
average power is the same on FM. Also FM requires the space of 5 SSB
signals.
The other question is with a +/- 60 KHz of Doppler shift and +/- 100 HZ for
SSB copy is it reasonable to expect computer correction of this magnitude?

If we were to use 2304 and 2448 the difference would be 144 MHz. Make TX
LHCP and RX RHCP some filtering on the satellite and you could have a linear
in band transponder with a low Doppler shift. AO-51 has used this approach
to separate two transmitters. At 2.4 GHz filters can be small and light
weight.

Here is some fresh meat for the nay sayers!

Art, KC6UQH
----- Original Message -----
From: "i8cvs" <domenico.i8cvs@tin.it>
To: "AMSAT-BB" <amsat-bb@amsat.org>; "William Erhardt" <k7mt@mt.net>
Sent: Monday, February 21, 2005 12:37 PM
Subject: [amsat-bb] Satellite Inquiry


> Hi William, K7MT
>
> If the satellite is a LEO (Low Earth Orbit) than you cannot use SSB for
the
> S band downlink because of the very high doppler at 2400 MHz
>
> On the other side a FM satellite with S band downlink is no good because
> of a single channel with the same problems of a terrestrial repeater in
> general but more complicated because a automatic tracking and automatic
> doppler compensation is needed for the uplink/downlink
>
> Actually we need a simple satellite with a linear transponder to
communicate
> with many stations at the same time using simple ground station equipments
> like we did with OSCAR-6, OSCAR-7, OSCAR-8 and the russian RS satellites
> also in LEO orbit
>
> A linear transponder with a 100 KHz or less passband would be OK
>
> The uplink frequency in U band 70 cm is ok for CW-SSB-RTTY-SSTV
>
> The downlink frequency in V band is OK for CW-SSB-RTTY-SSTV
>
> The above is the old Mode-B but also reverse to uplink in V band and
> downlink in U band would be OK as it would be the old Mode-J
>
> Actually to communicate CW-SSB-RTTY-SSTV via a linear transponder we
> have only AO-29 in Mode-J operational and the old OSCAR-7 in Mode-B
> and Mode-A but the last one is badly functioning.
>
> If you like the idea of a good satellite linear transponder I suggest to
> look at the article " A New Transponder for Amateur Satellites" designed
> by i5TDJ, Piero Moroni that was publisched in AMSAT-Newsletter june
> 1978
>
> This linear transponder was succesfully tested 3 time on board of
> Stratosferic Balloons fling over the Mediterranean sea from Sicily to
Spain
> where it was recovered but never was tested on board of an amateur
satellite
> so that it would be very interesting to try.
>
> Best 73" de
>
> i8CVS Domenico
>
> ----- Original Message -----
> From: William Erhardt <k7mt@mt.net>
> To: AMSATBBS <amsat-bb@amsat.org>
> Sent: Monday, February 21, 2005 6:17 PM
> Subject: [amsat-bb] Satellite Inquiry
>
>
> > Howdy from Bill K7MT AMSAT 33461.
> >
> > There is a possibility that amateur repeater can be placed on a
satellite
> > being built by Montana State University for launch in 2006. It is in
> > research stage right now so we need to put together a proposol for the
> > folks
> > at MSU to see if it will fit into their configuration.
> >
> > One question from Mike KE4AZN is which frequencies would be
incorporated.
> > Since we have three active FM birds V/U mode I am looking at proposing
U/S
> > FM or SSB   or  L/S  FM or SSB.
> >
> > I would like some input from the amateur community as to which mode they
> > would like to see ???? If you get a chance from me an email and the team
> > will look at ideas for this proposol.
> >
> > Looking forward to hearing from the amateur community.
> >
> > Cheers  Bill K7MT
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> ----
> Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> Not an AMSAT member? Join now to support the amateur satellite program!
> To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
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