Passive RF-RF entry system for vehicles
First Claim
1. A passive entry system for a vehicle that uses a bi-directional signal between the vehicle and a passive driver'"'"'s ID device comprising:
- a transmitter and receiver on a vehicle, and a transmitter and receiver in a passive driver'"'"'s ID device;
said vehicle being provided with a vehicle lock and a control for said vehicle lock, said vehicle transmitter and receiver taking a reference level signal strength of said passive driver'"'"'s ID device at said vehicle transmitter and receiver and storing a threshold value based on said level signal strength, and when a request occurs for access to said vehicle lock, said vehicle transmitter and receiver taking a current signal strength of a passive driver'"'"'s ID device, and comparing said current to said threshold values to determine whether the request is authorized.
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Accused Products
Abstract
A system for preventing unauthorized access to a vehicle having a passive entry system uses a bi-directional radio frequency, or RF-RF, signal. When using a RF-RF signal system, the signal from vehicle to a driver'"'"'s ID device is non-directional and not significantly distance limited. Consequently, a thief may be able to activate the entry system and gain access to the vehicle when the driver'"'"'s ID device is simply within range. The inventive passive entry system interrogates the ID device periodically following parking and locking of the vehicle. The signal strength levels received by the vehicle from the ID device are stored and a signal strength threshold level is computed. Upon a request for entry to the vehicle, a current signal strength level is compared to the signal strength threshold level. Based on that comparison, it is determined whether the request is valid or unauthorized. If the request for entry is deemed unauthorized, then access to the vehicle is not granted.
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Citations
14 Claims
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1. A passive entry system for a vehicle that uses a bi-directional signal between the vehicle and a passive driver'"'"'s ID device comprising:
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a transmitter and receiver on a vehicle, and a transmitter and receiver in a passive driver'"'"'s ID device;
said vehicle being provided with a vehicle lock and a control for said vehicle lock, said vehicle transmitter and receiver taking a reference level signal strength of said passive driver'"'"'s ID device at said vehicle transmitter and receiver and storing a threshold value based on said level signal strength, and when a request occurs for access to said vehicle lock, said vehicle transmitter and receiver taking a current signal strength of a passive driver'"'"'s ID device, and comparing said current to said threshold values to determine whether the request is authorized. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A passive entry system for a vehicle comprising:
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a bidirectional radio frequency signal transmitter and receiver on a vehicle and in a passive ID device, said vehicle incorporating a system for preventing unauthorized entry to said vehicle;
said transmitter and receiver within said vehicle periodically receiving measured signal strength levels from the ID device after said vehicle is parked and locked;
a control unit storing the signal strength levels and computes a threshold signal strength level based on said measured signal strength levels;
a device on said vehicle to request entry, said control requesting a current signal level when an entry request is received; and
said current signal level is compared to said computed threshold signal strength level to determine whether the request for entry is authorized, and a vehicle lock control unlocks a vehicle lock in response to a signal from said passive entry control unit at a point when it has been determined that the request for entry is authorized. - View Dependent Claims (9, 10, 11)
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12. A method for preventing unauthorized access to a vehicle having a passive entry system comprising the steps of:
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periodically measuring a signal strength level received by a passive entry receiver in the vehicle from a driver'"'"'s ID device after the vehicle is parked and locked;
storing the measured signal strength levels;
computing a threshold signal strength level based on said stored signal strengths; and
at a point in time when vehicle entry is requested, comparing the most recent measured strength level to said computed threshold signal strength level to determine whether the requested entry is authorized and then controlling vehicle entry accordingly. - View Dependent Claims (13, 14)
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Specification