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A wireless optical short-range communication system adapted for use as an intercom system. The system can be used in fast food restaurants and similar commercial institutions. The communication system includes a base station to interconnect via optical communication a group of substantially similar

A wireless optical short-range communication system adapted for use as an intercom system. The system can be used in fast food restaurants and similar commercial institutions. The communication system includes a base station to interconnect via optical communication a group of substantially similar physically spaced-apart, remote units. Each one of the remote units and the base units includes an optical emitter to transmit an optical message-carrying beam to the base station, and an optical receptor to receive an optical message-carrying beam from the base station. The base station includes a receptor for receiving the optical beam transmitted by the optical emitters of all of the remote units, and an optical emitter to relay the received optical beam to the optical receptors of all the remote units. The base station includes a clock arrangement for synchronizing the operation of the system 10 in a time division multiplexing carrier arrangement, by providing individual discrete time slots for the transmission of the signals from the remote units to the base unit, and for the transmission of the signals from the base unit to the remote units. In this regard, the base station and each one of the remote units include an oscillator to modulate the audio frequency on a predetermined subcarrier frequency, and another oscillator to modulate the subcarrier frequency on a predetermined optical infrared carrier frequency. This method of multiplexing a duplex communication system on a single carrier frequency can also be used in a radio frequency system as well as in an optical system.

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A wireless optical short range communication system utilizing a single optical carrier frequency comprising: a base station; a plurality of substantially similar spaced-apart remote units interconnected in optical communication with said base station; each one of said remote units including an optic

A wireless optical short range communication system utilizing a single optical carrier frequency comprising: a base station; a plurality of substantially similar spaced-apart remote units interconnected in optical communication with said base station; each one of said remote units including an optical emitter for transmitting an optical message-carrying beam at a predetermined optical carrier frequency to said base station; each one of said remote units further including an optical receptor for receiving an optical message-carrying beam from said base station; said base station including an optical receptor for receiving the optical message-carrying beam transmitted by the optical emitter of any of said remote units; said base station further including an optical emitter for repeating the message content of said optical message-carrying beam received from any one of said remote units to all of said remote units at said predetermined optical carrier frequency; clock means for generating recurring time slot signals, said signals including inbound signals and outbound signals; and said base station and said remote units including means responsive to said inbound and outbound signals for causing said station and said units to send and receive said beams during individual time slot signals.