(12) United States Patent ao) Patent No.: us 6,486,794 Bi
Calistro et al. (45) Date of Patent: Nov. 26,2002
(54) METHOD OF LOCATING A SUBSCRIBER
UNIT WITHIN THE COVERAGE AREA OF A
(75) Inventors: Enrique E. Calistro, Cooper City, FL
(US); Robert S. Flippo, Deerfield
Beach, FL (US); Troy A. Bailey, Lake
Worth, FL (US)
(73) Assignee: Motorola, Inc., Schaumberg, IL (US)
( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 1252 days.
(21) Appl. No.: 08/628,361
(22) Filed: Apr. 5, 1996
Related U.S. Application Data
(63) Continuation-in-part of application No. 08/606,950, filed on Feb. 26, 1996, now Pat. No. 5,740,541.
(51) Int. CI.7 H04M 11/00
(52) U.S. CI 340/825.49; 455/456; 455/457;
(58) Field of Search 340/825.49, 825.44,
340/825.36; 379/56.1; 455/39, 503, 440, 441, 11.1, 13.1, 500, 456, 457; 370/310, 312, 313, 314, 328
(56) References Cited
U.S. PATENT DOCUMENTS
3,663,762 A * 5/1972 Joel, Jr. 379/58
In a communication system (800) having transmitters (108) for transmitting location information to subscriber units (102) located with the transmitters' coverage areas, a method ol determining the location ol a subscriber unit. At least some ol the transmitters use different assigned time intervals to transmit their information, and a subscriber unit receiving such information can determine its location based, at least in part, on the time interval during which it received information. Received location information is stored in a dedicated portion (808) ol a subscriber unit's memory for later retrieval by the user. In a two-way system, a subscriber unit can transmit its stored location information to a system receiver (802) for storage in a system memory (804). The system memory (804) is accessed by a system operator or other authorized person to determine the location ol a subscriber unit and/or its pattern ol movement throughout the coverage areas.
14 Claims, 10 Drawing Sheets