Doppler effect and radar

The Doppler effect can be used to calculate the speed of any automobile . Calculations of change of radio waves from rotating satellites, for example, are used in the navigation systems of marine and can also be used in radar surveillance to determine the speed of automobiles.

RADAR speed detectors bounce microwave radiation off of moving vehicles and detect the reflected waves. These waves are shifted in frequency by the Doppler effect, and the beat frequency between the directed and reflected waves provides a measure of the vehicle speed .

By measuring the shift (or change) in phase between a transmitted pulse and a received echo, the target’s movement directly toward or away from the radar is calculated . This then provides a velocity along the direction the radar is pointing, called radial velocity.