Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1976-11-15
1978-12-12
Caldwell, Sr., John W.
Communications: electrical
Condition responsive indicating system
Specific condition
307233R, 343 5PD, G01S 902, G08B 1316
Patent
active
041298560
ABSTRACT:
An intrusion alarm of the kind in which a radiation field is transmitted in an area to be supervised; the reflected field is received and compared with the transmitted field, and a comparison signal is produced the frequency of which is indicative of the speed of movement of an object in the supervised area. A signal processor receives the comparison signal and generates an alarm if the comparison signal contains components in a selected frequency range. The processor includes a unique filter block which removes unwanted frequency components outside the range. The filter block includes a pulse generator which generates a constant amplitude pulse train, each pulse corresponding to a pulsation of the comparison signal, and control elements which control the duty cycle of the pulse train so that as the frequency of the comparison signal increases, the average level of the pulse train first increases and then decreases. The pulse train is integrated and operates an alarm signal generator when its average level rises above a preselected level.
REFERENCES:
patent: 3582870 (1971-06-01), Peterson et al.
patent: 3638210 (1972-01-01), Hankins et al.
patent: 3754222 (1973-08-01), Eisenberg
patent: 3801977 (1974-04-01), Cotter
patent: 3813669 (1974-05-01), Saunders
patent: 3925687 (1975-12-01), Solomon
Caldwell Sr. John W.
Contronic Controls Limited
Nowicki Joseph E.
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