I would expect . . . .
I may be misunderstanding your statement, but transmitters in different locations on the ground will show different curves. Remember you have Doppler on both the uplink and downlink too, so the beacon should be different than any uplinked signal (unless someone was running full Doppler tuning).
73, Drew KO4MA
Point well taken Drew - Thanks for your thoughts. I figured there would be some slight differences in uplink doppler as a function of ground location relative to TCA. Comparing the other traces to that of the presumed beacon, there appear to be two slopes - either matching closely or not. That made me suspect an additional transmitter. The 145 MHz doppler I would expect to be less pronounced than the 435 ... I suppose with a really clean display and accurate measurements and .. .. ..
I'm sure that an entire team of experts is involved in this type of spectral fingerprinting every day. Wish I had more time and tools, it could be a lot of (admittedly geeky) fun. Unfortunately the only waterfall I can get is an audio passband-width ala MixW or similar. The wideband waterfall you showed looks like an interesting tool. I'm envious.
Anyway, changing the uplink solves the immediate issue, but still leaves the question - could it have been a terrestrial carrier, relayed by FO-29 or possibly a spur from some other transmitter on a different bird... The fact that you saw energy on that frequency, with doppler could fairly well rule out a ground-based signal on the 145 MHz uplink, reckon ?
Thanks /;^)