Title: Burglar alarm device

Abstract: Burglar alarm apparatus includes an ultrasonic transmitter and an electromagnetic radiation transmitter whose signals are Doppler frequency shifted by an object moving through the radiation fields, the signals being received by respective demodulating receivers which provide respective electrical signals corresponding to the Doppler frequency. Frequency conversion apparatus is connected to one of the receivers to convert the output frequency thereof by a predetermined ratio to normalize or equalize the frequencies and a signal comparison circuit is provided to produce a signal in response to a ratio of the Doppler shifted signals within a predetermined tolerance range.

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Inventors: Heywang, Walter (Neukeferloh, DE)
Guntersdorfer, Max (Zorneding, DE)
Kleinschmidt, Peter (Munich, DE)

Application Number: 05/780806
Filing Date: 1977-03-24
Publication_date: 1981-06-23
Assignee: SIEMENS AG

Primary Class(es): 340/554 342/52, 367/94, 342/28
Other Classes: G08B13/16; G08B13/24; G08B13/18; G08B13/16; G08B29/00
US Patent Ref:

3074053	January, 1963	McDonough et al.	340/258	Electrical system and method for protecting premises subject to varying ambient conditions
3074054	January, 1963	Pearson	340/258	Electrical system and method for protecting premises subject to varying ambient conditions
3727216	April, 1973	Antonio	343/5PD	ELECTROMAGNETIC AND ULTRASONIC DOPPLER CORRELATION INTRUSION ALARM SYSTEM
3778823	December, 1973	Sato et al.	343/7VM	VEHICLE SAFETY DEVICE
3801978	April, 1974	Gershberg et al.	340/258A	ULTRASONIC-MICROWAVE DOPPLER INTRUSION ALARM SYSTEM
3846778	November, 1974	Galvin et al.	340/258A	COMBINED ULTRASONIC AND ELECTROMAGNETIC INTRUSION ALARM SYSTEM

Other Refs:
Primary Examiner: Caldwell Sr., John W.
Assistant Examiner: Nowicki, Joseph E.
Attorney: Hill, Van Santen, Steadman, Chiara & Simpson

Claims: