- I buy your "shorter" data consideration, but then how to explain that one negative value was stored if the height of the nominal terminal was chosen high enough to "forbid" negative values (the fact it was perhaps a corrupted data can't make "space" for the sign if not anticipated)?
There is one negative BFO number in the log, but no negative BTO numbers. The nominal terminal concept does not apply to the BFO data. For the BFO the standard is the frequency of the response expected, presumably the frequency of the assigned communications channel at that time.
If that negative BFO value at 00:19 is a valid measurement (rather than a noise/synchronisation issue),
one explanation is a very high rate of descent, apparently 13000ft/min.
- IMHO, I don't think that the localization of the nominal terminal can improve the accuracy: when the aircraft is in the area under under the satellite, any incertitude about the time gives a very high incertitude about the position: it is not like there was a physical mirror (for the signal) in this place. You can't use a "percentage incertitude" when subtracting the time of the known legs from the "total" time: you have to use the absolute incertitude.
I agree. My point there, which may not be very important, is that until the ground station to satellite element is removed the round-trip time has a large variable offset (due to the change in ground station to satellite range over the orbit) which means it is not immediately useful for positioning the ping-ring at any level of accuracy. Of course, full identification of the satellite position at the moment of the ping is needed to get complete ping-arc accuracy.