Communications: electrical – Systems – Call station
Patent
1976-07-14
1978-03-21
Caldwell, Sr., John W.
Communications: electrical
Systems
Call station
235468, 340147MD, 340274C, 343 5PD, G08B 1316, H03K 2300
Patent
active
040805948
ABSTRACT:
In a first mode, a security system uses the Doppler effect to permit the automatic activation of a bolt by the patterned movement of a reflecting card in the vicinity of a Doppler unit. In a second mode, the system behaves as a conventional intrusion detection system to activate an alarm for an unauthorized intruder present within an area to be monitored.
The first mode operates to verify a combination given a user implemented by the movement of a reflecting member towards and away from the Doppler unit based on a predetermined code. If the movement of the reflector is proper and within a predetermined time period, a valid comparison will be had to automatically cause a bolt to unlatch and open the door. The unit is placed in the second mode when all access to the door is prohibited and the system operates as a conventional intrusion detector.
REFERENCES:
patent: 3665443 (1972-05-01), Galvin
patent: 3680074 (1972-07-01), Lieser
patent: 3732465 (1973-05-01), Palmer
patent: 3733581 (1973-05-01), Kalmus
patent: 3760400 (1973-09-01), Galvin et al.
patent: 3769515 (1973-10-01), Clark, Jr.
patent: 3845461 (1974-10-01), Foreman
patent: 3891980 (1975-06-01), Lewis et al.
patent: 4009476 (1977-02-01), Lutz
Caldwell Sr. John W.
Nowicki Joseph E.
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