Passive remote access control system
First Claim
1. A method for controlling access to a vehicle which has a door and an engine, that method comprising the steps of:
- (a) periodically transmitting a first interrogation signal at a first rate from a control circuit on the vehicle;
(b) receiving the first interrogation signal at a remote control that is separate from the vehicle;
(c) upon receiving the first interrogation signal, transmitting a first reply signal from the remote control;
(d) receiving the first reply signal at the control circuit;
(e) after receiving the first reply signal, periodically transmitting a second interrogation signal at a second rate from the control circuit;
(f) receiving the second interrogation signal at the remote control;
(g) upon receiving each second interrogation signal, transmitting a second reply signal from the remote control;
(h) receiving each second reply signal at the control circuit;
(i) measuring strength of each second reply signal at the control circuit;
(j) activating a first function of the vehicle when the strength exceeds a first predefined threshold; and
(k) activating a second function of the vehicle when the strength exceeds a second predefined threshold.
3 Assignments
0 Petitions
Accused Products
Abstract
Access to a motor vehicle is controlled by periodically transmitting an interrogation signal from a control circuit on the vehicle. Upon receiving the interrogation signal, a hand-held remote control transmits a reply signal to the control circuit. The control circuit measures the strength of the reply signal and the activates a first function, such as unlocking a door of the vehicle, when the strength exceeds a first threshold level. Thereafter, when the signal strength exceeds a second threshold level, the control circuit activates a second function, for example enabling the engine to be started. When the signal strength drops below a third threshold activates a third function, such as locking the door.
105 Citations
16 Claims
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1. A method for controlling access to a vehicle which has a door and an engine, that method comprising the steps of:
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(a) periodically transmitting a first interrogation signal at a first rate from a control circuit on the vehicle;
(b) receiving the first interrogation signal at a remote control that is separate from the vehicle;
(c) upon receiving the first interrogation signal, transmitting a first reply signal from the remote control;
(d) receiving the first reply signal at the control circuit;
(e) after receiving the first reply signal, periodically transmitting a second interrogation signal at a second rate from the control circuit;
(f) receiving the second interrogation signal at the remote control;
(g) upon receiving each second interrogation signal, transmitting a second reply signal from the remote control;
(h) receiving each second reply signal at the control circuit;
(i) measuring strength of each second reply signal at the control circuit;
(j) activating a first function of the vehicle when the strength exceeds a first predefined threshold; and
(k) activating a second function of the vehicle when the strength exceeds a second predefined threshold. - View Dependent Claims (2, 3, 6)
3.The method as recited in claim 1 wherein the first rate is slower than the second rate. -
3. The method as recited in claim 1 wherein the step of activating a first function comprising unlocking a door of the vehicle.
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6. The method as recited in claim 1 further comprising activating a third function of the vehicle when the strength becomes less than a third predefined threshold.
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4. The method as recited in claim 4 wherein the step of activating a second function comprising enabling the engine to be started.
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5. The method as recited in claim 5 wherein the first predefined threshold is greater than the second predefined threshold.
- 7. The method as recited in claim 7 wherein the step of activating a third function comprising locking the door of the vehicle.
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9. A method for controlling access to a vehicle which has a door and an engine, that method comprising the steps of:
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(a) periodically transmitting an interrogation signal at a given rate from a control circuit on the vehicle;
(b) receiving the interrogation signal at a remote control that is separate from the vehicle;
(c) upon receiving the interrogation signal, transmitting a reply signal from the remote control;
(d) receiving the reply signal at the control circuit;
(e) measuring strength of the reply signal at the control circuit;
(f) activating a first function of the vehicle when the strength exceeds a first predefined threshold;
(g) after activating the first function, changing the given rate at which the interrogation signal is transmitted, and repeating steps (a) through (e); and
(h) thereafter activating a second function of the vehicle when the strength of the reply signal exceeds a second predefined threshold.
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- 10. The method as recited in claim 10 wherein the first predefined threshold is greater than the second predefined threshold.
Specification