Emergency sound detector device
First Claim
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1. An apparatus for detecting a warning sound emitted by an emergency vehicle or the like, comprising:
- first monitor means for monitoring a first predetermined range of frequencies including at least a portion of the spectrum of frequencies of the emitted warning sound;
second monitor means for monitoring a second predetermined range of frequencies, the frequencies of the second predetermined range of frequencies being lower than the frequencies of the first predetermined range of frequencies;
comparator means for comparing a first magnitude derived from an electrical signal detected to have a frequency within the first predetermined range of frequencies monitored by said first monitor means with a second magnitude derived from an electrical signal detected to have a frequency within the second predetermined range of frequencies monitored by said second monitoring means; and
indicator means, responsive to said comparator means, for indicating when the first magnitude is greater than the second magnitude.
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Abstract
A low-pass filter passes a spectrum of electrical signals which are utilized to establish a threshold level with which electrical signals having frequencies in a relatively higher range are compared to determine if a warning sound is present in the sounds in the vicinity of a receiver unit for receiving the ambient sound. If the rectified magnitude of the signals having the higher frequencies exceeds the rectified and variably adjusted magnitudes of the signals having lower frequencies, a visual indication is given to communicate the existence of a warning sound in the ambient sounds.
38 Citations
27 Claims
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1. An apparatus for detecting a warning sound emitted by an emergency vehicle or the like, comprising:
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first monitor means for monitoring a first predetermined range of frequencies including at least a portion of the spectrum of frequencies of the emitted warning sound; second monitor means for monitoring a second predetermined range of frequencies, the frequencies of the second predetermined range of frequencies being lower than the frequencies of the first predetermined range of frequencies; comparator means for comparing a first magnitude derived from an electrical signal detected to have a frequency within the first predetermined range of frequencies monitored by said first monitor means with a second magnitude derived from an electrical signal detected to have a frequency within the second predetermined range of frequencies monitored by said second monitoring means; and indicator means, responsive to said comparator means, for indicating when the first magnitude is greater than the second magnitude. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for warning of the presence of an emergency signal having a predetermined frequency, comprising:
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first monitor means for monitoring signals having frequencies within a first range of frequencies, said first range of frequencies including the predetermined frequency of the emergency signal; second monitor means for monitoring signals having frequencies within a second range of frequencies, said second range of frequencies including frequencies at which signals, generated by wind movement relative to said apparatus, have a substantial quantity of their energy; comparator means for comparing the signals monitored by said first monitor means with the signals monitored by said second monitor means; and indicator means, responsive to said comparator means, for communicating when the emergency signal has been monitored by said first monitor means. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An apparatus for warning of the presence of an emergency signal, comprising:
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first filter means for passing electrical signals having frequencies within a first predetermined range; first rectifier means for electrically rectifying the electrical signals passed by said first filter means and for providing an output thereof; second filter means for passing electrical signals having frequencies within a second predetermined range; second rectifier means for electrically rectifying the electrical signals passed by said first filter means and for providing an output thereof; comparator means for comparing the output of said first rectifier means with the output of said second rectifier means; and indicator means, responsive to said comparator means, for indicating when the output of said first rectifier means exceeds the output of said second rectifier means. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. An apparatus for warning of the presence of an emergency signal, comprising:
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receiver means for receiving electrical signals corresponding to ambient sound; band-pass filter means for passing the electrical signals having frequencies within the pass band of said band-pass filter means; first rectifier means for rectifying the electrical signals passed by said band-pass filter means; low-pass filter means for passing the electrical signals having frequencies within the pass band of said low-pass filter means; second rectifier means, including; operational amplifier means; variable resistive means, connected to said operational amplifier means, for establishing a threshold level; and amplitude controlling means, connected to said operational amplifier means, for limiting the amplitude of the electrical signals passed by said low-pass filter means; comparator means for comparing the output of said first rectifier means with the output of said operational amplifier means; and indicator means, responsive to said comparator means, for indicating when the ambient sound contains an emergency signal. - View Dependent Claims (23, 24, 25)
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26. An apparatus for warning of the presence of an emergency signal, comprising:
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first operational amplifier means for receiving electrical signals corresponding to ambient sounds; second operational amplifier means, having input means connected to an output of said first operational amplifier means, for providing a band-pass filter; third operational amplifier means, having input means connected to an output of said second operational amplifier means, for rectifying and amplifying; fourth operational amplifier means, having input means connected to the output of said first operational amplifier means, for providing a low-pass filter; fifth operational amplifier means, having input means connected to an output of said fourth operational amplifier means, for rectifying and amplifying; sixth operational amplifier means, having input means for receiving an output from said third operational amplifier means and from said fifth operational amplifier means, for providing a comparator output; seventh operational amplifier means for providing an oscillating signal; and eighth operational amplifier means, having input means for receiving the comparator output from said sixth operational amplifier means and for receiving the oscillating signal from said seventh operational amplifier means, for controllably outputting an oscillating signal corresponding to the oscillating signal of said seventh operational amplifier means. - View Dependent Claims (27)
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Specification