Hello,

Regarding Dopplers, http://amsat.org.ar/pass implements 4 select-able ways to follow Dopplers:

1) Both Uplink and Downlink Dopplers correction 2) Keep Uplink steady and modify Downlink 3) Keep Downlink steady and modify Uplink 4) Keep both Dopplers steady (No control)

1) Result: both stations QSOs like an HF SSB QSO (free hands, no tunning). 3) Result: for receiving station signal always on same frequency.

These can be applied either manually or thru CAT.

Thus allowing freedom of choice which way users prefer.

Appreciate and thanks users had suggested to implement these alternatives.

73, LU7ABF, Pedro

On Sat, Apr 14, 2018 at 1:43 PM, Vince Fiscus, KB7ADL [email protected] wrote:

At 12:29 PM 4/14/2018 +0000, Paul Stoetzer [email protected]wrote:

...

The general guidance in the early years of operating linear transponders was to adjust your transmitter to maintain a constant receive frequency. Experience with the Mode J transponder on FO-12 caused the gudiance to be updated to tuning the higher of the two frequencies. See the Sept 14, 1987 Amateur Satellite Report for more details ( http://www.ka9q.net/asr-1987.pdf).

I've always tended to adjust the uplink to the satellite, even on mode J. Never been chewed out for doing it that way though.

My question, for OM's doing computer control of their rigs. Is the software following the rule, or is it adjusting both uplink and downlink simultaneously?

I've always been curious about that.

Still using InstantTrack here. :-)

KB7ADL

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On Sat, Apr 14, 2018 at 12:43 PM, Vince Fiscus, KB7ADL [email protected] wrote:

At 12:29 PM 4/14/2018 +0000, Paul Stoetzer [email protected]wrote:

...

The general guidance in the early years of operating linear transponders was to adjust your transmitter to maintain a constant receive frequency. Experience with the Mode J transponder on FO-12 caused the gudiance to be updated to tuning the higher of the two frequencies. See the Sept 14, 1987 Amateur Satellite Report for more details ( http://www.ka9q.net/asr-1987.pdf).

I've always tended to adjust the uplink to the satellite, even on mode J. Never been chewed out for doing it that way though.

My question, for OM's doing computer control of their rigs. Is the software following the rule, or is it adjusting both uplink and downlink simultaneously?

You say "Is it following the rule?". As Paul said, the original "one true rule" of adjusting only Rx changed to adjusting the highest frequency frequency, but now (see Gould Smith's book, Appendix A) adjusting both is common if you have computer aided tuning. Both MacDoppler and SatPC32 can adjust both in this way (although MacDoppler can certainly be set to only change one frequency). I don't think that is in opposition to any rule. It is just an update of "The One True Rule".

I've always been curious about that.

Still using InstantTrack here. :-)

KB7ADL

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Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb