Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1977-09-21
1978-11-07
Tubbesing, T.H.
Communications: electrical
Condition responsive indicating system
With particular system function
340552, 343 14, G08B 1318, G01S 924
Patent
active
041248481
ABSTRACT:
A system for detecting intruder motion in selectable zones of a defined area is disclosed. The system is principally used as a line protector to detect intruders in the vicinity of a fence or wall and may be used as a virtual fence by employing a narrow-beam antenna and deep range coverage to detect an intruder crossing its line of sight. The system utilizes a transmitter for periodically sweeping the area to be protected and a receiver incorporating a narrow band filter which is variable to select a plurality of overlapping zones within the protected area, the presence of a reflective target in a selected zone resulting in a corresponding output signal. Means are provided to store such output signals from each zone and to compare received signals with previously-stored signals to detect differences in the target pattern of each zone. Differences exceeding a predetermined threshold level produce event signals which may result in a rescanning of the same zone, the system producing a zone trip signal only if an event is detected in a rescan. Upon completion of a complete scan of all zones, the system responds to selected alarm criteria to produce an alarm indication if there has been a preselected change in the target pattern.
REFERENCES:
patent: 3466652 (1969-09-01), Heyser
patent: 3657738 (1972-04-01), Carpentier et al.
patent: 3882495 (1975-05-01), Bolger
patent: 3932871 (1976-01-01), Foote
patent: 3967283 (1976-06-01), Clark et al.
Clark Robert V.
Linder Francis X.
Taylor William R.
Automation Industries, Inc.
Tubbesing T.H.
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