In the normal applications using Doppler shift registered in aircraft equipment:
The Doppler shift will only be detectable when a ground station is within range.
The Doppler shift will be doubled, because it is based on measuring the frequency of a reflected signal from the ground.
The Doppler shift, indicating ground speed, will always indicate a speed higher than the actual ground speed of the aircraft, due to depression of the beams.
The Doppler shift frequency will normally be displayed.