In the end - it doesn't matter a bit in the great scheme of the world's problems. It was just a bit of a puzzle to people who like to understand what is going on behind the wspr scenes.)Tony,
Yes, but as Hans reminded me most explanations of false decodes are based on assumptions.
Questions have come up regularly for many years, some causes are identified but the more obscure ones like you have experienced remain unexplained except by guesses.
In WSJT-X Hashtable.txt contains the hashtag of a call and it's 4 figure locator. The hashgtag is calculated for all received spots, not just those using complex transmissions. Does anyone actually know every use of hashtag.txt? Is it used for normal one-part messages?
Received power figure is stored in ALL_WSPR.txt. Is it referred to when decoding?
We often do not even know what decoder is being used by stations that give false spots. There are at least two other decoders in common use. WSPR daemon in the raspberry pi etc. and that in the Kiwi are the ones I know of. There are others and variants.
Looking at worldwide spot summaries makes me wonder if the majority of reports now are not from WSJT?
Some false callsigns like LQ0HGF in RP22 have come up from various stations for years.
It needs research from someone who fully understands all that goes on, I'm not aware of anyone who has done that. Perhaps those people realise there will never be a complete answer..
73 Alan G4ZFQ