Ultrasonic transmitter for burglar alarm system
First Claim
1. A burglar alarm system, comprising:
- a plurality of ultrasonic transmitter units, each of said units including means for detecting unauthorized intrusion or movement and means for transmitting a plurality of pulses that have a fixed code pattern of pulse durations and intervals between pulses, and a fixed ultrasonic frequency for each pulse in response to actuation of said detecting means;
at least one transceiver means for receiving said ultrasonic pulses and generating a radio frequency signal in response only to both said fixed ultrasonic frequency and said fixed pulse pattern; and
a central monitoring means for receiving said radio frequency signal and emitting an alarm signal in response thereto.
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Accused Products
Abstract
An ultrasonic transmitter for apprising a central burglar alarm system of an unauthorized event includes a transmitting diaphragm which is repeatedly struck by a metal ball driven by a lever. The lever is actuated by a toothed wheel which is rotated by a motor spring, the rotation being governed to maintain constant speed and constant ultrasonic pulse rate. The rotation of the wheel is stopped by a striker interfering therewith, the striker being spring biased to the non-interference position. Thus the striker must be retained in the interference position by a door, window, trip wire, or the like, and any disruption of these structures will trip the striker and cause the transmitter to generate an ultrasonic pulse train and sound an alarm.
17 Citations
23 Claims
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1. A burglar alarm system, comprising:
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a plurality of ultrasonic transmitter units, each of said units including means for detecting unauthorized intrusion or movement and means for transmitting a plurality of pulses that have a fixed code pattern of pulse durations and intervals between pulses, and a fixed ultrasonic frequency for each pulse in response to actuation of said detecting means; at least one transceiver means for receiving said ultrasonic pulses and generating a radio frequency signal in response only to both said fixed ultrasonic frequency and said fixed pulse pattern; and a central monitoring means for receiving said radio frequency signal and emitting an alarm signal in response thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a purely mechanical burglar alarm system, a device for signalling unauthorized intrusion or movement, comprising mechanical ultrasonic transmitter means for emitting a burst of ultrasonic pulses that have a fixed code pattern of pulse durations and intervals between pulses, and a fixed ultrasonic frequency for each pulse when driven,
mechanical motor means for driving said transmitter means when actuated, mechanical means for arming and disarming said device, and mechanical striker means for sensing unauthorized movement or intrusion to actuate said motor means.
Specification