Auto theft detection system

Claim 1

A system for locating a selected motor vehicle in a circumscribed geographic area, said selected vehicle being one of a multitude of motor vehicles dispersed randomly throughout said area with each vehicle having a different predetermined vehicle identification code assigned thereto; said system comprising: a first transmitter centrally stationed in said geographic area and adapted to broadcast a call signal, encoding means coupled to said first transmitter for modulating said call signal with any selected one of said different codes; each of said motor vehicles including at least one transponder inaccessibly concealed thereon, said transponder including a first receiver, a second transmitter adapted to broadcast a continuous predetermined locator signal, a decoder coupled to said first receiver adapted to provide an output signal in response to said call signal when said call signal is modulated with the vehicle identification code characteristic of the vehicle on which the transponder is concealed, and a relay coupled between said decoder and said second transmitter adapted to actuate the latter in response to said output signal; at least some of said transponders on different vehicles being adapted to broadcast identical locator signals; at least one finder vehicle of transportation adapted to be driver-operated; a second receiver mounted on said finder vehicle of transportation; and a direction finder on said finder vehicle of transportation responsive to said locator signal picked up by said second receiver to indicate the direction of the source of said locator signal relative to said further vehicle of transportation.

Claim 2

A system for locating a selected motor vehicle in a circumscribed geographic area, said selected vehicle being one of a multitude of motor vehicles dispersed randomly throughout said area with each vehicle having a different predetermined vehicle identification code assigned thereto; said system comprising: a first transmitter centrally stationed in said geographic area and adapted to broadcast a call signal, encoding means coupled to said first transmitter for modulating said call signal with any selected one of said different codes; each of said motor vehicles including at least one transponder inaccessibly concealed thereon, said transponder including a first receiver, a second transmitter adapted to broadcast a continuous predetermined locator signal, a decoder coupled to said first receiver adapted to provide an output signal in response to said call signal when said call signal is modulated with the vehicle identification code characteristic of the vehicle on which the transponder is concealed, and a relay coupled between said decoder and said second transmitter adapted to actuate the latter in response to said output signal; at least some of said transponders on different vehicles being adapted to broadcast identical locator signals; at least one finder vehicle of transportation adapted to be driver-operated; a second receiver mounted on said finder vehicle of transportation; and a direction finder on said finder vehicle of transportation responsive to said locator signal picked up by said second receiver to indicate the direction of the source of said locator signal relative to said further vehicle of transportation.

Claim 3

A system for indicating the proximity of a stolen vehicle comprising: at least one first transmitter means adapted to broadcast a call signal modulated with any selected one of a plurality of vehicle identification codes each assigned to a different one of a multitude of vehicles including said stolen vehicle; a transceiver affixed to said stolen vehicle, said transceiver including first receiver means for receiving said call signal, second transmitter means adapted to broadcast a continuous locator signal, and circuit means coupled between said first receiver means and said second transmitter means for activating said second transmitter means only upon reception by said first receiver means of said call signal modulated with said vehicle identification code assigned to said stolen vehicle; a plurality of second receiver means each adapted to receive and respond to said locator signal, said second receiver means being remote from said first transmitter means and separate from said stolen vehicle; and means responsive to said second receiver means for providing an indication of at least the bearing or distance of said stolen vehicle relative to said second receiver.

Claim 4

A system for indicating the proximity of a stolen vehicle comprising: at least one first transmitter means adapted to broadcast a call signal modulated with any selected one of a plurality of vehicle identification codes each assigned to a different one of a multitude of vehicles including said stolen vehicle; a transceiver affixed to said stolen vehicle, said transceiver including first receiver means for receiving said call signal, second transmitter means adapted to broadcast a continuous locator signal, and circuit means coupled between said first receiver means and said second transmitter means for activating said second transmitter means only upon reception by said first receiver means of said call signal modulated with said vehicle identification code assigned to said stolen vehicle; a plurality of second receiver means each adapted to receive and respond to said locator signal, said second receiver means being remote from said first transmitter means and separate from said stolen vehicle; and means responsive to said second receiver means for providing an indication of at least the bearing or distance of said stolen vehicle relative to said second receiver.

Claim 8

A system for locating a selected one of a multitude of vehicles of transportation where said vehicles are dispered randomly throughout a wide area and where at least some of said vehicles are in motion, comprising: a plurality of widely separated first transmitter means each adapted to broadcast a call signal; selectively operable means coupled to each of said first transmitter means for modulating said call signal with any one of a large plurality of predetermined vehicle identification codes each characteristic of a different one of said vehicles including said selected vehicle; a plurality of transponders each affixed to a different vehicle of said multitude of vehicles including said selected vehicle, each of said transponders including (a) first receiver means, (b) second transmitter means adapted to broadcast a continuous locator signal, and (c) circuit means coupled between said first receiver means and said second transmitter means for activating said second transmitter means only upon reception by said first receiver means of said call signal modulated with the vehicle identification code characteristic of the vehicle to which said each transponder is affixed; and a plurality of mobile locator stations separate from said vehicles and said first transmitter, each of said locator stations comprising second receiver means adapted to receive said locator signal and location indicator means responsive to said second receiver means for providing in relation to the locator station an indication of at least the bearing or presence of a vehicle having a transponder broadcasting said locator signal.

Claim 9

A system for locating a selected one of a multitude of vehicles of transportation where said vehicles are dispered randomly throughout a wide area and where at least some of said vehicles are in motion, comprising: a plurality of widely separated first transmitter means each adapted to broadcast a call signal; selectively operable means coupled to each of said first transmitter means for modulating said call signal with any one of a large plurality of predetermined vehicle identification codes each characteristic of a different one of said vehicles including said selected vehicle; a plurality of transponders each affixed to a different vehicle of said multitude of vehicles including said selected vehicle, each of said transponders including (a) first receiver means, (b) second transmitter means adapted to broadcast a continuous locator signal, and (c) circuit means coupled between said first receiver means and said second transmitter means for activating said second transmitter means only upon reception by said first receiver means of said call signal modulated with the vehicle identification code characteristic of the vehicle to which said each transponder is affixed; and a plurality of mobile locator stations separate from said vehicles and said first transmitter, each of said locator stations comprising second receiver means adapted to receive said locator signal and location indicator means responsive to said second receiver means for providing in relation to the locator station an indication of at least the bearing or presence of a vehicle having a transponder broadcasting said locator signal.