Cell-phone-based vehicle locator and "path back" navigator

Abstract

A hand-held, portable navigation system and method are integrated within a cellular telephone enclosure, resulting in a simplified architecture with fewer buttons to press and items to carry. The apparatus uses a cellular telephone having a microphone, a keypad, GPS receiver, a display, a memory, an earphone, a wireless transceiver, and a processor. The processor is programmed to receive a command through a user input device to determine the initial location of the user and activate the GPS receiver to obtain positional coordinates associated with the initial location. The coordinates are then stored in the memory. A subsequent command through a user input device causes the processor to determine the new location of the user, and the GPS receiver is again activated to obtain positional coordinates of the new location. The processor is further programmed to provide guidance to the user based upon the coordinates of the initial location and the new location enabling the user to return to the initial location from the new location. The user input device may be a portable wireless keyless entry device such as a ‘fob,’ in which case the processor is further operative to receive and store a vehicular DOOR LOCK command in memory, and determine the initial location of the user when the DOOR LOCK command is received and recognized by the telephone.

I claim: 
     
         1 . A hand-held portable navigation system, comprising:
 a cellular telephone having a microphone, a keypad, GPS receiver, a display, a memory, an earphone, a wireless transceiver and a processor programmed to perform the following functions:
 a) receive a command entered directly by a user through the keypad or microphone of the cellular telephone to determine the initial location of the user, 
 b) activate the GPS receiver to obtain positional coordinates associated with the initial location, 
 c) store the coordinates in the memory, 
 d) receive a subsequent command through a user input device to determine the new location of the user, 
 e) activate the GPS receiver to obtain positional coordinates of the new location, and 
 f) provide guidance to the user based upon the coordinates of the initial location and the new location enabling the user to return to the initial location from the new location. 
   
     
     
         2 . The hand-held portable navigation system of  claim 1 , wherein the guidance is provided to the user on the display of the cellular telephone. 
     
     
         3 . The hand-held portable navigation system of  claim 1 , wherein the guidance is provided to the user in the form of a graphical route on the display of the cellular telephone. 
     
     
         4 . The hand-held portable navigation system of  claim 1 , wherein the guidance is provided to the user in the form of a route superimposed on a map on the display of the cellular telephone. 
     
     
         5 . The hand-held portable navigation system of  claim 4 , wherein the map is previously stored in the cellular telephone. 
     
     
         6 . The hand-held portable navigation system of  claim 4 , wherein the map is loaded into the cellular telephone when the subsequent command is received. 
     
     
         7 . The hand-held portable navigation system of  claim 1 , wherein the guidance is provided to the user with voice prompts through the earphone.