Comment Re:PR Guys (Score 1) 491
Thanks for the links. I don't think D1 is a variable, they describe D2 as the Aircraft-Satellite Doppler shift, and you need two objects to measure a shift.
As the southbound aircraft passed the equator (satellite) you would indeed expect the aircraft's radial velocity component to drop to a minimum (something the north path would not see I expect). At the edge of the satellite coverage the aircraft will be close to the edge of the planet as seen from the satellite, so much of its velocity would be in the plane tangential to the Earth passing through aircraft and satellite (though not, one would expect, directly toward the satellite). The satellite has time variable velocity components that may be as high as 100 knots rel. to ground that also come into play. Its a continuum in between and a very interesting geometrical puzzle. Certainly the aircraft airspeed limits and norms would put a maximum limit on the Doppler shift due to aircraft motion.