Method and system for tracking stolen property

A method of tracking stolen property uses a continously powered radio receiver for receiving encoded signals from a central station. When the received signal corresponds to a unique code stored at the receiver, a GPS receiver and a radio transmitter located with the stolen property are connected for a predetermined period of time to a source of power so that a GPS signal received by the receiver is processed and the position data produced thereby is transmitted to the central station.

The present invention relates in general to methods and apparatus making 
use of the signals from the Global Positioning System (GPS) satellites to 
indicate the location of a GPS receiver, and it relates more particularly 
to a new and improved method and system for tracking the location of a 
stolen vehicle or other property in which a GPS receiver is disposed. 
BACKGROUND OF THE INVENTION 
In the United States alone, millions of dollars worth of automobiles, 
motorcycles, boats, and airplanes are stolen each year, and it would be 
desirable to provide a way to promptly locate the stolen property after it 
has been stolen and moved and before it can be dismantled or moved beyond 
the reach of the owner or other authorities. 
In U.S. Pat. No. 4,177,466 - Reagan there is disclosed a system for 
locating stolen property such as automobiles using a triangulation method 
of direction finding in which three mobile transmitter/receivers are 
adapted to receive a non-directional signal from a transmitter located in 
the stolen vehicle. The transmitter in the stolen vehicle must first be 
awakened by an encoded signal from a central station before transmitting 
the non-directional signal, which is then continuously transmitted for an 
indefinite period of time, presumably until the vehicle is recovered or 
the power source to the transmitter is exhausted. 
Since the Global Positioning System has been put into operation, many 
devices have been patented and marketed which make use of a GPS receiver 
to identify the position of a device in which the GPS receiver is 
disposed. Such devices are used, for example, by fisherman to find precise 
geographical positions on bodies of water, by trucking companies to track 
the location of their over-the-highway trucks, and automobile drivers to 
identify their own instantaneous geographical position. However, none of 
these systems are of use in locating a stolen piece of property unless the 
thief is willing to and actually does actuate the proper device in the 
vehicle to activate the receiver and transmitter located in the stolen 
piece of property. 
SUMMARY OF THE INVENTION 
Briefly there is provided in accordance with the present invention a novel 
method and apparatus for promptly locating a stolen vehicle or other 
property without the aid of anyone in the vehicle and, indeed, in spite of 
whatever such a person might do to defeat the system. Unlike the tracking 
and position finding systems and methods known in the prior art, the 
present invention provides for a continuous standby power system which 
maintains a radio receiver functional at all times. Upon receipt of a 
properly coded signal, unique to the receiver in question, a GPS 
receiver/transmitter is enabled and immediately begins to transmit a 
signal encoded with the precise geographical position (longitude and 
latitude) of the GPS receiver/transmitter. After a predetermined period, 
of say, five minutes, the GPS receiver/transmitter is disabled by a timer, 
but may be enabled by a subsequent signal from the central station to 
transmit the signal encoded with the position of the GPS 
receiver/transmitter for an additional predetermined period of time. 
The standby receiver and the GPS receiver/transmitter are physically 
mounted at a place on the vehicle or the like which is difficult to reach 
and from which it is almost impossible to be removed from the vehicle or 
to be disabled by a thief in a reasonably short period of time. For 
example, the electronic equipment, which is very small in physical size, 
may be mounted in a steel enclosure welded directly to the frame or engine 
block of the vehicle and connected to one or more antenna by a cable 
enclosed in a strong and massive conduit. 
In the case of a vehicle, when the vehicle is first acquired, the owner 
provides a central station, such as a police department, with the unique 
identification code of the vehicle. For example, the identification code 
may be the vehicle identification number affixed to the vehicle by the 
manufacturer. This number is generally referred as the VIN number. 
However, other identification codes may be used without departing from the 
invention. The standby receiver in the vehicle is set to respond to a 
signal encoded with this unique code and not to respond to any other 
identification code. 
When the owner of the vehicle realizes that the vehicle has been stolen, he 
or she reports the theft to the central station which then transmits a 
signal encoded with the unique identification code of the vehicle in 
question. Upon receipt of this signal by the standby receiver in the 
vehicle, its GPS receiver and transmitter are activated and the 
transmitter immediately commences to transmit to the central the GPS 
signals being received by the GPS receiver. The equipment at the central 
station then processes these GPS signals to determine the precise and 
substantially instantaneous position of the vehicle and transmits this 
information to a patrol vehicle and/or patrol vehicles located in the 
vicinity of the stolen vehicle. These patrol vehicles will receive this 
signal on their receivers and will be able to quickly find the vehicle. 
The GPS processing equipment is commercially available at a reasonable 
cost including CD-ROM maps etc.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawing and more particularly to FIG. 1 thereof, 
wherein the tracking system of the present invention may be seen to 
comprise a central station 10, one or more patrol vehicles 12 connected to 
the central station via radio, a standby radio receiver 14 mounted in a 
housing 16 located at the property to be tracked, a GPS receiver 18, and a 
GPS transmitter 20. The GPS receiver 18 and the GPS transmitter 20, like 
the standby receiver 14, are mounted in the housing 16 located with the 
piece of property to be tracked. The standby receiver 14 is directly 
connected to a power supply 21, such, for example, as the battery of the 
vehicle, and is thus energized at all times. The GPS receiver 18 and the 
GPS transmitter 20 are connected to the power supply 21 by switching 
circuit means 22 and are energized only when the switching circuits 22 are 
enabled by a signal from a timer 24. The enable signal from the timer 24 
is initiated when a properly coded radio signal transmitted from the 
central station 10 is received by the standby receiver 14 via an antenna 
26. The signal received by the standby receiver 14 is applied to a decoder 
28 and if the received code matches the code stored in the decoder 28, an 
output from the decoder enables the timer 24 which enables the switching 
circuits to connect the power supply 21 to the GPS receiver and to the GPS 
transmitter. After a predetermined time of about five minutes has elapsed 
the enable signal from the timer 24 to the switching circuits 22 
terminates and the power to the GPS receiver 18 and the GPS transmitter is 
interrupted. 
When the GPS receiver 18 and the GPS transmitter 20 are enabled, radio 
signals from a plurality of GPS satellites 25a, 25b, and 25c revolving in 
their respective orbits around the earth are intercepted by a GPS antenna 
30 and applied to the input of the GPS receiver 18. The GPS receiver 
processes the signals from the satellites and output position data 
corresponding to the geographical location of the GPS receiver. The 
geographical position data is applied to the transmitter 20 from which it 
is relayed to the central station 10 by means of radio waves developed in 
the transmitter 20 and transmitted from the antenna 26 or from another 
suitable antenna to the central station 10. 
This GPS signal when received at the central station 10 is processed in the 
conventional manner using commercially available equipment to provide the 
necessary geographical coordinates to identify the precise location of the 
GPS antenna 28. These geographical coordinates along with the 
identification characteristics of the vehicle are then transmitted from 
the central station 10 to one or more of the patrol vehicles 12 located in 
the vicinity of the stolen vehicle. 
While the present invention has been described in connection with a 
particular embodiment thereof, it will be understood that many changes and 
modifications may be made without departing from the true spirit and scope 
of the invention. Therefore, it is intended by the appended claims to 
cover all such changes and modifications which fall within the true spirit 
and scope of the invention.