Browse Prior Art Database

LOCATION TRACKING SYSTEM WITH HAND-OFF CAPABlLlTlES

IP.com Disclosure Number: IPCOM000007727D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2002-Apr-17
Document File: 6 page(s) / 277K

Publishing Venue

Motorola

Related People

Brad Murray: AUTHOR [+2]

Abstract

A personal location device with transmit capa- bilities, such as a GPS receiver incorporated in a paging transceiver, can triangulate its position using GPS satellite transmissions and transmit the posi- tion coordinates to a paging system. This allows the paging system to track the location and movement of the user of the portable transceiver. If a user of one of these transceivers requires help, an emer- gency signal can be transmitted to the paging sys- tem upon the user pushing a button. This emer- gency signal will also contain the current location coordinates of the user. This allows an operator at the paging system to guide help towards the user. The transceiver continues to transmit it's location coordinates so that the operator has the most cur- rent location of the person in need of help. Under ideal conditions this locator system works well.

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MOlVROLA Technical Developments

8

LOCATION TRACKING SYSTEM WITH HAND-OFF :CAPABlLlTlES

by Brad Murray and Greg Cheraso

  A personal location device with transmit capa- bilities, such as a GPS receiver incorporated in a paging transceiver, can triangulate its position using GPS satellite transmissions and transmit the posi- tion coordinates to a paging system. This allows the paging system to track the location and movement of the user of the portable transceiver. If a user of one of these transceivers requires help, an emer- gency signal can be transmitted to the paging sys- tem upon the user pushing a button. This emer- gency signal will also contain the current location coordinates of the user. This allows an operator at the paging system to guide help towards the user. The transceiver continues to transmit it's location coordinates so that the operator has the most cur- rent location of the person in need of help. Under ideal conditions this locator system works well.

  However, there are situations where the user's transceiver may not be able to continue transmit- ting updated location coordinates. Specifically, the user's transceiver battery may run low, especially if the transceiver must transmit location coordinates for an extended period of time. This, in turn, will cause the transmission output power of the trans- ceiver to be reduced to the point where the paging system may lose contact with the transceiver. By the time help arrives at the last known location, the user may have moved to another location. This requires the arriving help to perform a physical search of the entire surrounding area of the last known loca- tion of the user in trouble. What is needed is a per- sonal locator system which can continue tracking a transceiver even when the paging system loses con- tact with the transceiver.

  Figure 1 is a block diagram of a portable paging transceiver incorporating a GPS receiver. The port- able unit contains both a GPS receiver and a paging transceiver. As shown, a single processor controls both the GPS receiver and the paging transceiver. However, the GPS receiver could have a dedicated processor for triangulation calculations to determine

latitude and longitude coordinates. In either case these coordinates are stored in a memory. Once stored, the paging transceiver processor can acknowl- edge this information to the paging system. The pag- ing transceiver processor can also selectively acti- vate and deactivate the GPS receiver to minimize battery drain on the portable unit and can change the transmit/receive frequencies of the transceiver section.

  Figure 2 is a flow chart of a transceiver operating in an emergency mode. The transceiver's processor monitors the controls and detects a "help" button being activated. The transceiver sets it's transmit tiequency to a predetermined wide area channel. The processor then activates the GPS receiver and sets a transmit timer. The GPS receiver triangulates it's current locati...