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RE: FO-20??



You are partially right.  The big difference however is that UO-14 is FM and
therefore a quite wide bandwidth so a KHz or two does not make much
difference, whereas FO-20 is SSB or CW, and a hundred Hz or so makes a
difference.  Some doppler correction on the uplink of the FM satellites is
still a good idea, but not as critical as the SSB birds.

73
-------------------------
Jim Walls - K6CCC
k6ccc@amsat.org
http://home.earthlink.net/~k6ccc/
Ofc:  626-302-8515    FAX:  626-302-9999
Res:  626-914-4641



----------
From:  Christopher E. Phelps[SMTP:n2yqp@flash.net]
Sent:  Friday, June 16, 2000 9:57 PM
To:  kk5do@AMSAT.Org; Paul Williamson
Cc:  ne1h@ne1h.dyndns.org; amsat-bb@AMSAT.Org
Subject:  Re: [amsat-bb] FO-20??

According to my Sat book, FO-20 even thought it has a 100kHz bandwith, still
needs doppler shift on its uplink. Where as UO-14 which is now voice, has
AFC on its receiver so that stations didnot have to adjust for doppler. I
notice at times I donot have to adjust my uplink (on UO-14) as much as my
downlink for a while ,then there seems to be a sudden shift up for me to get
in clearly. Generally if not too crowded I can get in to it without being
aimed right at it. I can get a good signal durring the max of the pass, even
with my arrow aimed at the ground. Meanwhile, AO- 27 has been very poor in
signal quality lately.
----- Original Message -----
From: "Paul Williamson" <kb5mu@AMSAT.Org>
To: <kk5do@AMSAT.Org>
Cc: <ne1h@ne1h.dyndns.org>; <amsat-bb@AMSAT.Org>
Sent: Friday, June 16, 2000 7:02 PM
Subject: Re: [amsat-bb] FO-20??


> At 05:58 PM 6/16/00 +0005, Bruce Paige wrote:
> >for operating digital satellites, you correct both up and downlink
> >frequencies.
>
> Not necessarily. Some digital satellites have uplink receivers that are
broad enough to not require tuning on the uplink, and you can minimize
interference to other fixed-channel stations by leaving your uplink fixed.
>
> >  however, on analog voice satellites, you correct the higher of
> >the two frequencies as that is the freq most affected by doppler.
>
> That's the old rule for manual operations, not the best rule.
>
> See http://www.amsat.org/amsat/features/one_true_rule.html
> for the long version of my thoughts on the subject.
>
> 73  -Paul
> kb5mu@amsat.org
>
>
>
> ----
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>

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