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Re: AO-27 Freq, and my first AO-27 QSO



    I really don't understand what you are stating here.  Doppler shift on a
    rapidly moving object is a reality based on the laws of physics. 
    Correcting for Doppler is NEVER wasteful, but makes good sense.

    If my HT was capable of tuning steps smaller than 5 kHz, then I would
    constantly compensate for Doppler on both uplink and downlink, much as I
    do on my home based Oscar station.  As it is, an HT user is well served
    by the 5 frequency pairs I posted originally:

    >     436.805 - 145.845
    >     436.800 - 145.850
    >     436.795 - 145.850  middle of pass
    >     436.790 - 145.850
    >     436.785 - 145.855

Let's consider myself and N6TQS, who lives close enough that we hear
each other's uplink.  Suppose we're both operating on AO-27, and one
of us are compensating for doppler on the uplink, and the other other
does.  Let's assume 15 KHz bandwidth for purposes of discussion.  So
close to AOS, one of us will be occupying from 145.8425 to 145.8575,
and other from 145.8375 to 145.8525, thus 145.8375 thru 145.8575 will
be unavailable.  Similarly, at LOS, this will be from 145.8425 to
145.8625.  During the entire pass, 145.8375 thru 145.8625 will be
used, or say, 25 kHz out of the 200 KHz satellite sub-band instead of
15 KHz.

    So, if I wanted to tune the center of the transmitted signal at AOS, I
    would have my receiver set to 436.802.  If I also wanted my signal close
    to the center of the satellite receiver pass band, I would tune down 3.5
    kHz and transmit on 145.8465. 

I used pairs like that to successfully work the MIR/SAFEX repeater[SK?].
The concept isn't bad, and it's very helpful on SSB, so one's signal
doesn't wander up or downthe  passband during the period of a pass.  But
it is unnecessary here, since we're running a single channel and AO-27
does that work for us.

    Especially if I am accessing the bird with a low ERP, concentrating my
    uplink signal at the center of the sat receiver pass band will help
    guarantee my success.

This has been discussed before and AO-27 hears just as well, with or 
without doppler correction.  So there is no advantage to it and it
avoids affecting fewer other users who may be operating on other
satellites.

    I am not using any more bandwidth, and am not being wasteful.  Whoever
    told you that John must have been pulling your leg.

I can't blame anyone else, it's my own damned fault.  Fortunately, it
is mostly a quibble right now and a very minor thing to improve upon.
If we're lucky, maybe it won't be quite so academic starting mid-autumn.
*grin*  By the way, Mike, you have a great signal out here in California 
and i definitely number you amongst the more considerate operators on
AO-27.
	                 73's and good luck,

                            -- KD6PAG
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