Regarding Observation 954225 …
Does anyone know what that interesting wave pattern is in the middle of this file? Is this another satellite crossing paths? Just seems odd that the Doppler pattern would go back and forth like that.
That is an amateur radio operator sending a constant tone out to try to find themselves in the downlink.
–Roy
K3RLD
[edit] interesting that it appears the transponder functions all the way through the beacon… I didn’t think that was possible (but never tried)
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Interesting! Are they trying to find the downlink on this satellite, or was it another one nearby?
I went back and looked at a lot of the observations of this particular satellite and mode and this is the only one I can find that looks like this. Do you know of any others that I could view and listen to?
All of the CAS and XW satellites are SSB/CW linear transponders for use in the amateur radio service. AO-7 and the Funcube satellites are, as well. They allow amateur radio operators (such as myself) to make contacts via the satellites using Single Side Band voice modulation or CW modulation (using morse code). So the radio operator has to tune two different frequencies on their radio (or radios): the uplink and downlink. There is a rough correlation between the two for all of these sats, so an operator will pick a downlink frequency and then, as I do, start transmitting something like “K3RLD trying to find my uplink” as I tune the uplink frequency until I can hear my own voice. you can see SSB voice contacts occuring on to the right of the CW beacon. That zig-zagging line is somebody transmitting a continuous tone, trying to find their uplink.
I hope that makes sense.
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Makes perfect sense now. Thanks for the explanation!