sentence: Hard objects are things like buildings, hills, and mountains.
sentences_after: Metallic objects are anything made of metal, like 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 and distance of objects which have reflected the radar transmitter's high powered pulses.
concept_name: hard object
headings: Electronics Pulse circuits