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:
http://www.amsat.org/amsat/features/one_true_rule.html
73, Joe kk0sd
----- Original Message ----- From: ehekman@cox.net To: AMSAT-BB@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 WB6YTE _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb