@ Gysbreght
Thanks for posting a spreadsheet. I'm currently going through it, and hopefully working towards getting a meaningful result from the final calibration point, i.e.
17:07:15 UTC 5°20.4'N 102°49.5'E 025°T 469 KTS GS FL350
The above position from FR24 is effectively the last reliable 'steady state' one. The average BFO around +/ 15 secs of the above time as reported by Inmarsat is 134.6 Hz (135).