VECTOR MECHANICS BASED DOPPLER SHIFT ESTIMATION FOR AIR TO GROUND COMMUNICATIONS

A method of estimating Doppler shift for air to ground communications comprises obtaining an initial position of an aircraft during flight, wherein the aircraft includes an onboard database with stored positions for a plurality of ground station towers; when a subsequent position of the aircraft nears a stored position of a closest ground station tower, requesting a Doppler shift estimation for the closest ground station tower; obtaining a current position of the aircraft when requesting the Doppler shift estimation; defining an aircraft position vector from the initial position to the current position; defining a tower position vector from the initial position to the stored position; subtracting the aircraft position vector from the tower position vector to determine an aircraft to tower position vector; differentiating the aircraft to tower position vector with respect to time to determine a velocity magnitude to the closest ground station tower; and calculating a Doppler shift.