Showing papers on "Intrusion detection system published in 1985"

Self-diagnostic ultrasonic intrusion detection system

Abstract: The disclosed self-diagnostic ultrasonic motion detection system includes an ultrasonic transceiver operative in a transmit mode and in a receive mode. In normal operation, the ultrasonic transceiver in its transmit mode has a characteristic electrical impedance. Potential electro-mechanical, electrical, acoustical, and other sources of false and failure of alarm situations manifest as changes in the electrical impedance of the transceiver in its transmit mode. The electrical impedance is monitored, changes from the nominal are detected, and a suitable self-diagnostic alarm signal is produced in response thereto.

Keyboard hold-down functions for a multi-zone intrusion detection system

Abstract: An intrusion detection system of the type employing a keypad utilizing the keys to conventionally enable a user to key in a secret code capable of arming or disarming the system. The present apparatus includes a hold-down feature whereby if any one of the plurality of keys on the keypad is depressed for a predetermined interval, the apparatus detects the predetermined timing interval and transmits an audible sound to the user indicating that the requisite timing interval has transpired. Upon receipt of the audible sound, as depending upon the test to be performed, the user is thus informed that the system will now commence the test procedure as defined by the selected key. Thus the system includes apparatus for detecting the requisite timing interval. Upon detection of the requisite timing interval a storage means is activated, which storage means is associated with the selected key. Upon activation of the storage means, the output of the storage means is directed to the intrusion system whereby the intrusion system is now programmed to undergo the test procedure or operating procedure which is defined by the selected key as depressed for the requisite timing interval.