Document Type and Number:
Japanese Patent JPS5141480
Kind Code:
B1
Abstract:
Ultrasonic intrusion alarm system with oppositely phased voltage doublers and timing capacitors for distinguishing between the movements of an intruder and other movements such as air turbulence. An operational amplifier in the input stage provides common mode rejection; an integrator prevents actuation of the alarm by disturbances of short duration, and fail-safe means is included to prevent the system from being deflated by disabling it.
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Application Number:
JP4677071A
Publication Date:
November 10, 1976
Filing Date:
June 26, 1971
Export Citation:
International Classes:
G01S15/52; G08B13/16; (IPC1-7): G08B13/16; G01S3/80