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Doppler correct and frequencies - from a newbie!



All,

I'm kinda curious.  I've been tracking and copying the pacsats and I've
noticed an oddity.  I'd just as soon not learn a bad habit, so I figured I'd
ask.

With automatic control and doppler correction, I can't seem to center the
discriminator to keep the satellite decoding on the EVM.  How do others do
it?  It goes like this.

Take KO-23, the uplink is suppose to be 145.900 and the downlink is 435.175.
So I setup the software with those values and when the sat comes over the
horizon, I start to pick it up.  But the discriminator indication on the 847
is way off to one side.  I've found that I have to crank in sometimes as
much as 4K to get it centered and the modem decoding.

So, my real question is as follows....

Do you ....

a) leave the uplink as calculated for doppler based upon the base freqs and
center the discriminator (for best decode) on the downlink?  (in other
words, just adjust the downlink)

b) adjust both the uplink and the downlink to match the offset to center the
discriminator

I presume that both the TX and RX at the sat could vary different directions
as time goes by, perhaps even away from one another.  You know where the TX
is because you can center for that, but what is the preferred method for the
RX.

Do you also setup your software to counteract for this for each sat, so you
don't have to do it manually?

I don't want to learn any bad habits, so I figured I'd ask.  Thanks in
advance,

Alan

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