Passive intrusion detection system

Details Passive intrusion detection system Passive intrusion detection system

1977-02-09

1980-04-08

Caldwell, Sr., John W.

Communications: electrical

Condition responsive indicating system

Specific condition

310319, 331 65, 340604, G08B 2100, H01L 4110

Patent

active

041975308

ABSTRACT:
An intrusion detection system in which crystal oscillators are used to provide a frequency which varies as a function of fluctuations of a particular environmental property of the atmosphere, e.g., humidity, in the protected volume. The system is based on the discovery that the frequency of an oscillator whose crystal is humidity sensitive, varies at a frequency or rate which is within a known frequency band, due to the entry of an intruder into the protected volume. The variable frequency is converted into a voltage which is then filtered by a filtering arrangement which permits only voltage variations at frequencies within the known frequency band to activate an alarm while inhibiting the alarm activation when the voltage frequency is below or above the known frequency band.

REFERENCES:
patent: 2571171 (1951-10-01), Van Dyke
patent: 3296549 (1967-01-01), Johnson
patent: 3689907 (1972-09-01), Guajardo
patent: 3895912 (1975-07-01), Naumann

Affiliated with

Also associated with

Rating

Passive intrusion detection system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Passive intrusion detection system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Passive intrusion detection system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-976350