Originally Posted by
Hyperveloce
mm43, are you sure that this P-channel continuous monitoring of the doppler shift between the A/C and the 3F1 satellite was implemented by the MH370 AES ?
I ask because the Inmarsat annex 1 clearly states (red circling D2) that "D2 is not corrected by system" (meaning both GES and AES) hence it is "the observed frequency offset".
All aircraft that ever enter the U.S. airspace (it would be pretty safe to presume that it means all 777's) are required by 47 CFR 87.145(d)
47 CFR 87.145 - Acceptability of transmitters for licensing. | LII / Legal Information Institute to correct their transmit frequencies for Doppler effect relative to the satellite and to bring them under 335 Hz.
Annex 1 could be interpreted to say that D2 is the real Doppler, D1 is the correction, and "measured frequency offset" is the part of D2 that is not subtracted by D1. It's a stretch but it is consistent with my first paragraph.