the radar transmitter's pulses or bursts of radio energy hit and bounce back (they are "reflected") from hard or big metallic objects. hard objects are things like buildings, hills, and mountains. big things made of metal include aircraft, bridges, or even objects in space, like satellites. the reflected radar energy is detected by radar pulse receivers which use both pulse and digital circuits together. the pulse and digital circuits in radar pulse receivers are used to show the location, distance, and speed of objects which have reflected the radar transmitter's high powered pulses.