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AO40 frequency shift



 >Hello Cliff, Dave

 >Now I'm confused!

 >Sounds like we are now talking about an anomaly, not to do with computer
 >Doppler prediction, magnetourquing or s/c temperature.

 >Is this what we're considering?

 >If so, what are the magnitudes of the anomaly and is there an observed
 >pattern (eg, AO-10 & the Aleutians)?

 >This was something I wasn't considering before but now I'm quite interested.

Yes, Howard that is it exactly....I've got tons of e-mail suggesting
everything from the neighbors's television to coriolis force, and I'm
sure neither of them are the problem!!!

I've made the observations when the magnetorguers are off, at night with
no wind blowing and I'm sure the temperature hasn't changed .1°, everything
has been on and warmed up for hours.

The change is random, and so far I've observed nothing like what we saw
on one of the low orbit birds years back...The "poor reception to the east"
phenomena that some German ham so aptly documented at the time.

The g3ruh psk decoder does a very good job of indicating these frequency 
changes,
it has a diode string that indicates 10 Hz, but my Icom will only step
50 Hz on the mike button.  That works ok, with the occasional glitch. But
with the Icom 821 no one has been able to get it to work using the mike
button control as they use a 400~ resistor in one of the up/down control
lines. I separated the up/down control lines with a switch.  That works
just fine now, but I have to "tend" the switch because of these anomolies.

The tracking programs indicate the doppler swing in the expected and proper
direction, but the satellite actual frequency is different in what is 
predicted.

The magnitude of the freq change varies, and is sometimes very short lived.
The rate of the change seems about equal to the "normal at the time" rate.
But that is difficult for me to determine.  The time of the change varies from
a minute or so to (I cannot accurately say how 'cause I don't take time to sit
and watch it).

As little as I know about these things it looks like a computer program that
would use the actual beacon frequency being received as an input could control
the radio.  I got the expensive CI-V  computer interface from Icom and that
had a data sheet that seems to indicate all the tools are there for someone
to do that.  My junk box two transistor computer interface worked just as well,
so the Icom interface was an expensive proof.

Howard get out the rubidium, and paste one together.  I thank you and all the
wonderful gang out there that responded to my inquiry.

I'll forever just remain a beta tester, but very happy to do that!!

Tnx agn, Howard...


            73, Dave wb6llo@amsat.org
                      Disagree; I learn.........



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