Car security system and method
First Claim
1. A security system for indicating access to a protected area comprising a transmitter means providing a radio frequency signal, power supply means for supplying electric power to said transmitter means, receiver means adapted to continuously receive said radio frequency signal as an input signal and to provide a receiver output signal in response to said received input signal, indicating means operatively coupled to said receiver means and responsive to a disabling condition of an insufficient said input signal to provide said receiver output signal, said radio frequency signal having a first and second frequency component, said receiver output signal in response to said first frequency component and a second receiver output signal in response to said second frequency component, said indicating means adapted to be responsive to said first and second receiver output signals for providing an indicator output signal in the absence of one of said first and second receiver output signals.
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Accused Products
Abstract
A security and alarm system for vehicles includes a portable receiving unit with a remote alarm therein and a transmitter unit physically placed with a vehicle. The transmitter unit broadcasts a continuous radio frequency signal received by the receiver unit. The transmitter unit includes a cadmium sulfide photocell sensor responsive to access into the vehicle which will turn the transmitter off and activate a local alarm. The receiver unit constantly monitors the transmitter signal and will activate an alarm if the transmitted signal is not present for any reason, such as the vehicle being towed beyond the broadcast range.
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Citations
18 Claims
- 1. A security system for indicating access to a protected area comprising a transmitter means providing a radio frequency signal, power supply means for supplying electric power to said transmitter means, receiver means adapted to continuously receive said radio frequency signal as an input signal and to provide a receiver output signal in response to said received input signal, indicating means operatively coupled to said receiver means and responsive to a disabling condition of an insufficient said input signal to provide said receiver output signal, said radio frequency signal having a first and second frequency component, said receiver output signal in response to said first frequency component and a second receiver output signal in response to said second frequency component, said indicating means adapted to be responsive to said first and second receiver output signals for providing an indicator output signal in the absence of one of said first and second receiver output signals.
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17. A method of detecting access to a vehicle that utilizes a radio frequency transmitter in the vehicle and operated by a sensor responsive to access to the vehicle, the transmitter providing a radio signal having a first and second frequency component, further including a remote radio signal receiver adapted to receive the transmitted signal and providing a first output signal in response to reception of the first frequency component and a second output signal in response to reception of the second frequency component, alarm circuitry responsive to the absence of one of the first and second output signals from the receiver comprising the steps of:
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A. continuously transmitting the two frequency-component radio signal by the transmitter; B. continuously monitoring by the receiver of the transmitted signal; and C. activating the alarm circuitry in the absence of one of the first and second frequency signals. - View Dependent Claims (18)
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Specification