Alarm system having improved false alarm rate and detection reliability
First Claim
Patent Images
1. An alarm system comprising:
- a plurality of sensors providing overlapping coverage of a common protected area and each providing a sensor signal when actuated by an alarm condition in the protected area;
OR circuit means coupled to said sensors and operative in response to any one of the sensor signals to provide a first alarm signal having high detection reliability; and
logic circuit means coupled to said sensors and operative in response to sensor signals from at least two of said sensors present within a predetermined time interval to provide a second alarm signal having a low false alarm rate;
said time interval commencing immediately upon the occurrence of the first of said sensor signals.
4 Assignments
0 Petitions
Accused Products
Abstract
An alarm system has two output modes, one providing relatively high detection probability and the other providing relatively low false alarm probability. Two or more sensors are coupled to an associated logic circuit which provides a first alarm output in response to actuation of any one of the sensors, and a second alarm output in response to actuation of the two or more sensors within a predetermined time interval.
-
Citations
5 Claims
-
1. An alarm system comprising:
-
a plurality of sensors providing overlapping coverage of a common protected area and each providing a sensor signal when actuated by an alarm condition in the protected area; OR circuit means coupled to said sensors and operative in response to any one of the sensor signals to provide a first alarm signal having high detection reliability; and logic circuit means coupled to said sensors and operative in response to sensor signals from at least two of said sensors present within a predetermined time interval to provide a second alarm signal having a low false alarm rate; said time interval commencing immediately upon the occurrence of the first of said sensor signals. - View Dependent Claims (2, 3, 4)
-
-
5. An alarm system comprising:
-
a plurality of sensors providing overlapping coverage of a common protected area and each providing a respective sensor signal when actuated by an alarm condition in the protected area; an OR circuit coupled to said plurality of sensors and operative in response to any one of the sensor signals therefrom to provide a first alarm signal having high detection reliability; a logic circuit for each of said sensors operative in response to the simultaneous presence of a gating signal derived from a sensor signal from one of said sensors and a sensor signal from at least one other of said sensors to provide an output signal; and an OR circuit operative in response to any one of said output signals to provide a second alarm signal having a low false alarm rate; said gating signal commencing immediately upon the occurrence of the first of said sensor signals.
-
Specification