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Re: Failed attempt on FO-29.

George Henry wrote:

> While the practice of leaving one's uplink frequency constant and 
> adjusting the downlink for doppler may be the only practical way to 
> operate in half-duplex, it is not good operating practice, in that your 
> downlink signal can drift into an on-going QSO, causing interference 
> that you are REQUIRED BY LAW to avoid.  This is PRECISELY the reason 
> that the recommended procedure has always been to adjust one's UPLINK to 
> maintain a constant downlink frequency.

On a mode V/U (or mode J if you prefer), or any other mode where the 
downlink frequency is higher in frequency than the uplink, this is 
neither the preferred nor secondary method.

The preferred method is full doppler tuning wherein the uplink and 
downlink frequencies are constantly adjusted to maintain the frequency 
constant at the satellite.  This is almost impossible to do unless all 
stations involved in the conversation are running computer control of 
the doppler.  If that is not possible, then the higher frequency should 
be adjusted and the lower frequency should be left alone.  In the case 
of FO-29, that means, adjust the downling frequency.  If AO-10 every 
comes back, then adjust the uplink frequency.

With that said however, there are others that will argue the opposite. 
I will tell you that in my opinion, even though the recommendation is to 
adjust the higher frequency, I personally find that it is much easier if 
the downlink only is adjusted.  The reason I say that is that by 
adjusting the receive frequency, you (not the other guy) has control of 
how you like to listen to SSB (not everyone is the same).

I will also tell you that in either case, there will in the real world 
times when the opposite frequency is adjusted.  This is primarily 
because the different operators in the conversation are not in the same 
place and the dopplers are different.

Jim Walls - K6CCC
Ofc:  818-548-4804
AMSAT Member 32537 - WSWSS Member 395
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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