Parking sensor systems use ultrasonic proximity detectors embedded in the front and/or rear bumpers, to measure the distances to nearby objects at low level.

The sensors measure the time taken for each sound pulse to be reflected back to the receiver.

Backup cameras are alternatively known as 'reversing cameras' or 'rear view cameras'

A backup camera is a special type of video camera that is produced specifically for the purpose of being attached to the rear of a vehicle to aid in backing up.