Vehicle intrusion detector
First Claim
Patent Images
1. A detector for generating an alarm signal in response to the detection of an intrusion in the perimeter of a space substantially enclosed and having a glass portion, said detector comprising:
- means for detecting a positive air compression wave in said space and for generating an enable signal in response thereto;
means for detecting the breakage of said glass portion and for generating a breakage signal;
means for detecting a negative air compression wave in said space and for generating a negative pressure signal in response thereto;
comparator means for receiving said enable signal and for generating a threshold signal and for receiving said negative pressure signal and for comparing said negative pressure signal to said threshold signal and for generating an instantaneous negative pressure signal in response thereto; and
means for generating an alarm signal in response to the generation of either said instantaneous negative pressure signal or said breakage signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A vehicle detector is disclosed wherein either a glass breakage signal or a door opening signal causes an alarm. The glass breakage signal is caused by the detection of high audio frequency simultaneously accompanied by the detection of a positive pressure change. The door opening signal is generated by the detection of a negative pressure change, which is not preceded by a positive pressure change.
19 Citations
19 Claims
-
1. A detector for generating an alarm signal in response to the detection of an intrusion in the perimeter of a space substantially enclosed and having a glass portion, said detector comprising:
-
means for detecting a positive air compression wave in said space and for generating an enable signal in response thereto; means for detecting the breakage of said glass portion and for generating a breakage signal; means for detecting a negative air compression wave in said space and for generating a negative pressure signal in response thereto; comparator means for receiving said enable signal and for generating a threshold signal and for receiving said negative pressure signal and for comparing said negative pressure signal to said threshold signal and for generating an instantaneous negative pressure signal in response thereto; and means for generating an alarm signal in response to the generation of either said instantaneous negative pressure signal or said breakage signal. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A detector for generating an alarm signal in response to the detection of an intrusion in the perimeter of a space substantially enclosed and having a glass portion, said detector comprising:
-
means for detecting a positive air compression wave in said space and for generating an inhibit signal in response thereto; means for detecting the breakage of said glass portion and for generating a breakage signal; means for detecting a negative air compression wave in said space and for generating a negative pressure threshold signal in response thereto; means for receiving said negative pressure threshold signal and said inhibit signal and for generating an instantaneous negative pressure signal in response to said negative pressure threshold signal in the absence of said inhibit signal; and
,means for generating an alarm signal in response to the generation of either said instantaneous negative pressure signal or said breakage signal. - View Dependent Claims (8, 9, 10)
-
-
11. An intrusion detector for generating an alarm in response to the detection of an intrusion in the perimeter of a vehicle substantially enclosed and having a glass portion, said detector comprising:
-
means for detecting a positive air compression wave in said vehicle and for generating an enable signal in response thereto; means for detecting the breakage of said glass portion and for receiving said enable signal and for generating a breakage signal in response to said breakage of said glass portion and the presence of said enable signal; means for detecting a negative air compression wave in said vehicle and for generating an initial negative pressure signal in response to the absence of said enable signal and the detection of said negative air compression wave; and means for generating an alarm signal in response to the generation of either said initial negative pressure signal or said breakage signal.
-
-
12. A detector for generating an alarm in response to the detection of an intrusion in the perimeter of a space substantially enclosed, said detector comprising:
-
microphone means for generating a first signal in response to the detection of acoustic waves in said space, said acoustic waves representative of change in air pressure or presence of audio sound in said space; first circuit means for receiving said first signal and for generating a breakage signal, said breakage signal representative of the detection of audio sound by said microphone means; low frequency filter means for receiving said first signal and for producing a low frequency signal in response thereto; positive threshold detection circuit means for receiving said low frequency signal and for generating an enable signal in response to said low frequency signal exceeding a positive threshold; negative threshold detection circuit means for receiving said low frequency signal and said enable signal and for generating an instantaneous negative pressure signal in response to said low frequency signal exceeding a negative threshold signal;
wherein said negative threshold detection circuit means increases said negative threshold signal in response to the presence of said enable signal; andmeans for generating an alarm signal in response to the generation of either said initial negative pressure signal or said breakage signal. - View Dependent Claims (13)
-
-
14. A intrusion detector for generating an alarm in response to the detection of an intrusion in the perimeter of a vehicle substantially enclosed and having a glass portion and an ambient air pressure, said detector comprising:
-
means for detecting the breakage of said glass portion and for generating a breakage signal; means for detecting an air pressure in said vehicle greater than said ambient air pressure and for generating an inhibit signal in response thereto; means for receiving said inhibit signal, and for detecting an air pressure in said vehicle less than said ambient air pressure and for generating a negative pressure signal in response to the absence of said inhibit signal and the detection of air pressure less than said ambient air pressure; and means for generating an alarm signal in response to either said negative pressure signal or said breakage signal. - View Dependent Claims (15, 16, 17, 18, 19)
-
Specification