Originally Posted by
Golf-Mike-Mike
Already posted that they said they went back through weeks of other Malaysian 777 flights they had data for and examined the signal for those going northbound compared to the southbound ones and saw a Doppler shift (I guess?). So they're making a comparison not looking at MH370 alone.
similarly no talk of "jitters" I read in another thread.
Satellite sees a Doppler shift when the aircraft is on a trajectory that brings it closer or further away from it. E.g., if the satellite is 45 degrees above the horizon from the point of view of the aircraft and the aircraft flies at 490 knots and steady altitude directly towards the satellite, and communications between the satellite and the aircraft occur at the frequency of 1.6 GHz, Doppler shift is 1.6e9*cos(45)*(490*1.852/3600)/299792=1903 Hz.
If the same aircraft were to turn either X degrees left or X degrees right, radial speed (the component directed towards the satellite) would decrease, transverse speed would increase, and Doppler shift would decrease. But, since the system has mirror symmetry, the satellite has no way of knowing whether the aircraft turned left or right.
Like I said, we have a highly symmetric configuration (one satellite) and nothing evident to break the symmetry.