[amsat-bb] Re: Question about tuning for doppler and SatPC32

Gary "Joe" Mayfield gary_mayfield at hotmail.com
Tue Nov 21 05:04:17 PST 2006

The rule of thumb if you are adjusting just one band is adjust the higher 
band.  In mode B this would be the uplink.  In mode J it would be the 
downlink.  This will minimize how much you walk across the transponder. 
Computer control of both is even more efficient, but arguably less fun.  The 
definitive guideline can be found here:



----- Original Message ----- 
From: <ehekman at cox.net>
To: <AMSAT-BB at amsat.org>
Sent: Monday, November 20, 2006 3:40 PM
Subject: [amsat-bb] Re: Question about tuning for doppler and SatPC32

>I have found it much easier to maintain QSOs when both stations use 
>computer controlled Doppler correction on both links.  The downlink 
>frequency errors are easily tracked with the receiver RIT control.
> It seems to me that the best practice out of courtesy to others is to 
> always use Doppler correction on the uplink.  If that is done then the 
> uplink and downlinks frequencies stay nearly constant at the satellite and 
> the receiving station can follow the signal with computer control and very 
> minor RIT adjustments.  If uplink Doppler correction is not used then 
> receiving stations must manually track the downlink frequency.
> Since I have found it easy to implement and it makes QSOs much easier to 
> maintain I am curious why computer controlled Doppler correction is not 
> used by all stations.  Are there some radios still in use that do not have 
> the capability for computer control?
> Ed
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