Mobile telephone location system and method

Patent 5844522 Issued on December 1, 1998. Estimated Expiration Date:

October 13, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

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Inventors

Assignee

Trackmobile, Inc.

Application

No. 543031 filed on 10/13/1995

US Classes:

342/457, Land vehicle location (e.g., bus, police car340/825.49, Location indication455/456.5At system equipment (i.e., base station)

Examiners

Primary: Blum, Theodore M.

Attorney, Agent or Firm

Brown, Martin, Haller & McClain, LLP

Foreign Patent References

0417944 EP. 03/13/1991

International Class

G01S 003/02

Abstract

A wireless network based location system and method uses an existing wireless communication network to locate the position of any active phone or transceiver unit in the network. The system includes a plurality of agile vector sensor units, one each installed at each antenna site in the network, and a remote central monitoring station to which wireless network users can call for assistance in the event of an emergency. The system is designed to locate a portable phone transceiver unit using the reverse voice channel signal transmitted by the transceiver unit. Each agile vector sensor unit locks onto the reverse voice channel to determine azimuth and signal strength in the reverse voice channel, and also tracks any changes in voice channel by monitoring the forward voice channel. In the event of a voice channel change, the sensor unit tunes to the new voice channel. The azimuth, signal strength, and reverse voice channel information collected is used to track the location of a transceiver unit in real time.