Pittway Corporation

John E Foster

Christopher R Paul

Kenneth G Eskildsen

Ying Xiong

A method and a device for detecting the breakage of glass. A glass breakage detector that uses an acoustic transducer, an analog-to-digital converter, and a processing means which uses software algorithms to determine if a signal received by the acoustic transducer is a result of glass breaking. The glass breakage detector also uses amplifiers which have a greater gain response for higher frequency components in the received signal. The glass breakage detector is also able to correct the offset error generated by the amplifiers. The processing means or digital signal processor (DSP) uses a feature extraction software algorithm that extracts characteristics of the received sound using a plurality of filters centered at different frequencies and a rules analysis software algorithm to compare the extracted features to features from glass breakage and false alarms. The DSP is also capable of transmitting the extracted features to an external computing device for further analysis. The DSP may use different software routines which may be selected by a user to process the signal from the acoustic transducer. The software algorithms used by the DSP may be modified or customized for optimally detecting a glass breakage event.

Glass breakage detector

A glass breakage detector that uses an acoustic transducer, an analog-to-digital converter, and a processing means which uses software algorithms to determine if a signal received by the acoustic transducer is a result of glass breaking. The glass breakage detector also uses amplifiers which have a greater gain response for higher frequency components in the received signal. The glass breakage detector is also able to correct the offset error generated by the amplifiers. The processing means or digital signal processor (DSP) uses a feature extraction software algorithm that extracts characteristics of the received sound using a plurality of filters centered at different frequencies and a rules analysis software algorithm to compare the extracted features to features from glass breakage and false alarms. The DSP is also capable of transmitting the extracted features to an external computing device for further analysis. The DSP may use different software routines which may be selected by a user to process the signal from the acoustic transducer. The software algorithms used by the DSP may be modified or customized for optimally detecting a glass breakage event.

A method and apparatus for testing a balanced diode mixer and local oscillator combination in a microwave receiver. The diodes comprising a balanced mixer are unbalanced in a selective, controlled manner to generate an offset signal. The unbalancing of the mixer is accomplished by heating one of a pair of mixer diodes. By measuring an offset voltage output of the balanced diode mixer after one of the diodes has been heated, it is possible to measure an artificially created diode mismatch offset voltage and thereby verify that the balanced mixer/oscillator combination is working properly. The heating step is performed by either forward biasing the mixer diode or by placing a resistive heating element adjacent to the diode.

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Huntington, NY, United States of America

John E Foster