Going over the last nine months of observations for STRAND-1, actual observations seem to tail off in January of '23. This observation is one of the last, if not the last, times I’ve seen what looks like a proper signal in the waterfall which corresponds to decoded data. Skipping through more recent observations I’ve found decoded data from time to time but no waterfall presence and no indication that the data is from STRAND-1. What say ye, fellow observers?
What’s an appropriate methodology? In December and January at least, decodes with beginning with hex characters C0 80 01 0C 02 80 0C had a strong correlation with good, Doppler-correct signals on the waterfall. Perhaps that’s a good starting point.
Given that is rare to have decoded data and not signal in the waterfall, I think it is safe for this satellite and transmission type to assume that decoding without signal in waterfall is a false positive.
On the other hand, your approach of checking if the data start with the known sequence is an extra verification.
For the doppler, as the satellite is still tracked from space-track.org well, I think every signal that shows extreme drift (more than 4-5 KHz) is something else.
Finally one more hint is to make sure that the visible signal is similar to the known ones, mode- and bandwidth-wise.
This is one of those times where being able to search for a specific hex string in the data would be super helpful, but I see from recent posts in another thread that it’s not possible yet. Meanwhile, I’ve set some shortcuts and vet a few dozen observations per day; thank you for posting the links.
Though the review process is by no means complete, I have yet to find any valid decodes from STRAND-1 in recent months. Consequently I’ll mark the transmitter “inactive” in the database, and link to this discussion in the citation. I defer to anyone with deeper experience on whether this is the right procedure but it’s certainly appropriate based on what we’ve seen since January.
(Edit to add: …and I’m sorry I submitted the same change twice.)