Did Inmarsat use similar calculations for calibration before MH370?

March 8, 2015

Inmarsat claims the calculations it did were original to MH370.  Is that believable?  First the basic calculations are


  1. Time delay to calculate distance.
  2. Doppler shift to calculate velocity.

These are not new and are taught in textbooks.  Such calculations are standard.

Let us consider some alternatives.  Prior to MH370 as part of its services:

  1. Inmarsat didn’t calculate any information on aircraft position or velocity.
  2. Inmarsat did calculate position and velocity but not using time delay or Doppler shift.
  3. Inmarsat used time delay and Doppler shift but with other parts of the signal system.
  4. Inmarsat used some totally different methods for position and velocity.

It seems likely that what Inmarsat means by novelty is that the specific handshake signal it had not used to calculate position and velocity, but that it was calculating such things using other parts of the signal system.  Even this might be a fib however.

What about calibration? However Inmarsat calculated position and velocity, why not use time delay and Doppler to check it?  Don’t engineers calibrate one technique against another? Maybe they were already doing that.

If they were using time delay and Doppler shift with one signal, how novel is it to apply it to another signal?

Assuming Inmarsat provided position tracking and velocity information prior to MH370, and that it used physics principles of time delay and Doppler Shift, then this was likely known to its customers including Russia and China. So they didn’t have to do anything special in terms of penetrating Inmarsat to do this.

That the handshake signal could be used for position tracking and velocity calculation might require more inside know-how, but could have been easily obtained by Russia or China?  They were using the equipment on their own jets as customers of Inmarsat?

This is draft and preliminary. The above is hypotheses and speculation. Comments and corrections welcome. Please restate as questions. All other disclaimers apply.


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