I was thinking about adding a feature to my FT8/4 Assistant program to display in a histogram the delta times from the last minute's worth of decodes and maybe eventually to enable the user to nudge the PC clock backwards or forwards by a few milliseconds. This may or may not be a good idea but my problem is that so far I have not been able to convert the UDP decode message time offset back to anything resembling the DT column in the WSJT-X Band Activity window and I would very much appreciate some help. In the specification the Delta Time is described as a float serialised as a Double. When I examine the eight bytes following the SNR bytes I see a consistent correlation between the Band Activity DT and the pattern of bytes. So I know I am looking in the right place, which is the eight bytes starting at (zero base) byte 32 . Here is a screen shot from an Excel worksheet where I compare samples of the Band Activity DT with their Decode byte array bytes:-
I have several issues here that I do not understand :- 1. The pattern of bytes for negative and positive Delta Times are identical so the sign is lost.2. Between SNR and Delta Frequency there are nine bytes, not the eight I expected for a Double. Byte 40 appears to be surplus.3. DT 0 is suspiciously all zeros when DT 0.1 seems to be a very large number.4. Bytes 33 and 34 are identical. Please can somebody make sense of this for me. 73 de G4SWY Derek +++
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