Observation 943678: VZLUSAT-1 (42790)

Regarding Observation 943678

In this pass the satellite VZLUSAT-1 is clearly there but the shift is not proper to decode the CW beacon, or at least it’s hard to.

It seems to me the beacon is badly drifted from nominal although the pass is a success as the satellite is there.

What is the procedure to adjust the tracking parameters to account for that?

73 de Pedro LU7DID

Indeed there is a drift on its transmitter.
The procedure is to check other good passes on other stations and see if the drift is stable. Watch out when you checking as some stations hasn’t adjust their SDRs so the signal may have also the drift from the SDR.
After finding the drift the next move is to go to https://db.satnogs.org and suggest the right drift of the transmitter, after that it will be checked and approved or not.

In VZLUSAT-1 case it looks like that we don’t have a stable drift, for example compare the passes on your station with these ones:

It looks like the drift is dynamic and for now we don’t have any mechanism to calculate dynamically transmitter drifts. I don’t know either if there is any way to calculate it or estimate it with a good accuracy.

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The difference between passes seem to be associated with the Doppler shift, being the directo overhead pass the worst.

CW needs a freq shift of about 600 Hz in order to decode by ear, and the current shift is anywhere between 0 and 30 Hz, shifting higher by some 300 Hz might be a compromise as in bad passes would yield some 350 Hz shift and in the good ones would be more like 1 KHz which is still decodeable by hear.

73 de Pedro, LU7DID