초록 ▼

An alarm system for detecting the pattern of acoustic signals resulting from the breaking of glass utilizes transducers to convert the acoustic waves to electrical signals and then analyzes the signal strength, the frequency content and the pattern of the signal and no signal intervals to discrimina

An alarm system for detecting the pattern of acoustic signals resulting from the breaking of glass utilizes transducers to convert the acoustic waves to electrical signals and then analyzes the signal strength, the frequency content and the pattern of the signal and no signal intervals to discriminate the breaking of glass from background or spurious noises. The system also determines the level of background noise and compensates therefor in determining whether an alarm signal is to be generated.

대표청구항 ▼

A circuit for generating an electrical indicating signal in response to a pattern of acoustic signals which comprises: a. transducer means for receiving the acoustic signals and providing electrical signals at a first output terminal; b. threshold means coupled to said first output terminal and prov

A circuit for generating an electrical indicating signal in response to a pattern of acoustic signals which comprises: a. transducer means for receiving the acoustic signals and providing electrical signals at a first output terminal; b. threshold means coupled to said first output terminal and providing an output signal at a second output terminal in response to signals having a magnitude exceeding a threshold level; c. switch means coupled to said first output terminal and having a third output terminal and first control terminal, said switch means being actuated by a signal at said first control terminal; d. signal analyzing means coupled to the third output terminal and having a fourth output terminal and a second control terminal, said signal analyzing means being actuated by a signal at said second control terminal to indicate the presence of at least one frequency component in the signal at said third output terminal; e. output logic means coupled to the third and fourth output terminals and having a third control terminal and a fifth output terminal, said output means providing the electrical indicating signal at said fifth output terminal when actuated by a control signal and signals at the third and fourth output terminals, and f. timing circuit means coupled to the second output terminal and responsive to the signal from said threshold means for providing first, second and third actuating signals to the first, second and third control terminals respectively, the timing of said actuating signals being determined in accordance with the pattern of acoustic signals to be responded to.