Called person locating system in office telephone installations - has proximity detector automatically redirecting call to nearest substation frequented by person concerned

摘要

Each one of a group of telephone sets is equipped with an emitter of personal codes and a receiver of response signals. Each subscriber is equipped with a portable proximity receiver with a personal code store programmed to respond to an equal code with a coincidence signal. The same is decoded in receiver stages in the local exchange and applied to a line selector which switches the call through to the corresp. telephone set where the ring signal is released. The personally carried proximity receiver can be based either on frequency discrimination or on code recognition, both using radio transmission techniques. A further embodiment generates and transmits coded signals by means of infrared emitters and receivers, with the power supply derived from built-in solar cells.