Originally Posted by jimjim1
... As far as I recall they have not released the position of the notional (I refuse to use the inexplicable 'nominal') satellite. They have not stated how they think they know the position of the notional aircraft.
There has been a deal of work done by others on reverse engineering the original BFO data, and it was successful in confirming a baseline when the aircraft was on the ramp at KUL. Though what those who did the work originally didn't realize, was that the AES was only correcting for the aircraft position and motion, and that the residual of 88/89Hz on the ramp was in fact the SAT motion Doppler on account of its orbital eccentricity.
Likewise, it is now possible to compare the BTO data and get a match, though the AES 'pass-through delays' vary with the bit rate of the channel in use. The released data identifies the bit/s e.g. 600/1200/10500. The common rate is 1200 and 180~200uSecs looks like the delay to use.
As for the "nominal terminal", my understanding is that it is outside the SAT and on the ground (surface) at 0° 64.5°E. This allows the L-band stuff to be dealt with, while ignoring the C-band SAT ~ GES effects. I hope to get a graphic together in the near future to demonstrate the principles described.