CAGE DOOR STATUS INDICATION

摘要

ABSTRACTIn a multi-deck underground cage each door has a switchfitted to it to provide a door-open or door-closed signal.The signals identify the respective door and are used tomodulate an infrared carrier signal which is transmitteddownwardly and reflected to a receiver. Informationdecoded from the carrier signal is displayed to indicatethe status of each door at a location remote from the cage.