Vehicle tracking system
First Claim
1. A vehicle tracking system, comprising:
- an array of fixed cellular signal receiving and transmitting units each covering a predetermined area and forming part of a cellular telephone network, each fixed cellular unit including means for transmitting cellular voice and control channel signals identifying said unit;
a signal processing unit for mounting in a vehicle, the unit including signal generating means for generating emergency signals on detection of an emergency condition, the signal generating means including means for continuously scanning all voice and control channel signals from any fixed cellular units within range of the vehicle during an emergency condition, means for determining the signal strengths of any received cellular voice and control signals, and means for transmitting an emergency signal from the vehicle for each set of received signals, each emergency signal including the received cellular control signals and determined signal strengths; and
a central monitoring means for receiving said emergency signals and for computing an approximate vehicle location from said cellular control signals and signal strengths.
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Accused Products
Abstract
A vehicle tracking system makes use of a conventional cellular telephone network including a plurality of fixed cellular transmitter sites each covering a predetermined area. The system includes a plurality of cellular signal processing units for installation at hidden locations in vehicles to be monitored. Each unit is connected to one or more different sensors in the vehicle, at least one of the sensors being a break-in detector for detecting tampering with the vehicle, and to a cellular antenna, and includes a controller for monitoring the sensor outputs and initiating an emergency message transmission to a remote monitoring station in the event of actuation of a sensor. The car processing unit monitors site identifying signals and signal strengths of transmissions from adjacent cellular transmitter sites in an emergency, and the emergency message includes vehicle identifying information, cell site identifying information, and signal strength information which will be dependent on distance from the cell site. The monitoring station includes a computer for determining and displaying an approximate vehicle location from the incoming cell site identifying and signal strength information.
659 Citations
16 Claims
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1. A vehicle tracking system, comprising:
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an array of fixed cellular signal receiving and transmitting units each covering a predetermined area and forming part of a cellular telephone network, each fixed cellular unit including means for transmitting cellular voice and control channel signals identifying said unit; a signal processing unit for mounting in a vehicle, the unit including signal generating means for generating emergency signals on detection of an emergency condition, the signal generating means including means for continuously scanning all voice and control channel signals from any fixed cellular units within range of the vehicle during an emergency condition, means for determining the signal strengths of any received cellular voice and control signals, and means for transmitting an emergency signal from the vehicle for each set of received signals, each emergency signal including the received cellular control signals and determined signal strengths; and a central monitoring means for receiving said emergency signals and for computing an approximate vehicle location from said cellular control signals and signal strengths. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16)
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15. A method of locating and tracking a vehicle, comprising the steps of:
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installing a modified cellular phone unit in a vehicle including means for detecting an emergency situation in the vehicle and means for generating and transmitting a sequence of emergency signals at periodic intervals after detection of an emergency situation while the emergency situation exists, the cellular phone unit being usable as a standard cellular phone during non-emergency conditions; detecting an emergency situation in the vehicle; continuously monitoring and scanning the cell voice and control channel identifying information transmitted from cellular phone network cell sites within range of the vehicle in the cellular phone unit in the vehicle while the emergency situation exists; extracting and storing signal strength data in the vehicle unit from the signals received from adjacent cell sites during each scan; continuously updating the stored signal strength data using the continuously scanned voice and control channel signals during the emergency situation; transmitting emergency signals at predetermined intervals from the vehicle unit to a central controller at a remote monitoring station during the emergency situation, each emergency signal including an alarm code, vehicle identifying information, and cell identifying and signal strength information generated from the stored signal strength data; and processing the alarm information at the central computer to compute an approximate vehicle location from the cell identifying and relative signal strength data.
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Specification