The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 21, 1989
Filed:
Dec. 14, 1987
Ronald T Miyahira, Honolulu, HI (US);
Kenneth Fasen, San Diego, CA (US);
H. M. Electronics, Inc., San Diego, CA (US);
Abstract
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.