Apparatus and method for identifying speech and call-progression signals
First Claim
1. A method for performing real-time recognition of speech and call-progression tones from electrical energy on a signal line including the steps of:
- a. providing a digitized signal representing electrical energy on a signal line;
b. correlating N neighboring portions of the digitized signal and reporting no speech present if the correlation does not exceed a predetermined threshold;
c. performing Fast Fourier Transform analysis on the digitized signal and identifying a first, a second, and a third largest frequency-domain maxima;
d. determining whether the first and second largest maxima are above a threshold frequency and reporting speech present if either the first or the second largest maxima are below the threshold frequency; and
e. determining whether a ratio of the first largest maxima to the third largest maxima exceeds a predetermined value and reporting a tone present if the ratio is larger than the predetermined value, and reporting noise present if the ratio is smaller than the predetermined value.
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Accused Products
Abstract
A method for real-time recognition of speech and call-progression tone energy includes the steps of digitizing an analog signal present on a signal line, correlating N neighboring portions of the digitized signal, performing FFT analysis on the digitized signal, identifying the three largest frequency-domain maxima, determining whether the two largest maxima are above a threshold frequency, and determining whether the ratio of the largest to the third largest maxima exceeds a predetermined value. According to the present invention, the steps of the method may be performed in real time using fixed-point hardware by approximating the correlation and FFT functions.
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Citations
13 Claims
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1. A method for performing real-time recognition of speech and call-progression tones from electrical energy on a signal line including the steps of:
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a. providing a digitized signal representing electrical energy on a signal line; b. correlating N neighboring portions of the digitized signal and reporting no speech present if the correlation does not exceed a predetermined threshold; c. performing Fast Fourier Transform analysis on the digitized signal and identifying a first, a second, and a third largest frequency-domain maxima; d. determining whether the first and second largest maxima are above a threshold frequency and reporting speech present if either the first or the second largest maxima are below the threshold frequency; and e. determining whether a ratio of the first largest maxima to the third largest maxima exceeds a predetermined value and reporting a tone present if the ratio is larger than the predetermined value, and reporting noise present if the ratio is smaller than the predetermined value. - View Dependent Claims (2)
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3. An apparatus for performing real-time recognition of speech and call-progression tones from electrical energy on a signal line comprising:
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a. means for receiving a first plurality of digitized signal samples representing electrical energy on a signal line; b. means for attenuating the digitized signal samples and forming a filtered signal, the means for attenuating coupled to the means for receiving; c. means for decimating the filtered signal and forming a decimated signal, the means for decimating coupled to the means for attenuating; d. means for correlating a second plurality of neighboring portions of the decimated signal and calculating a maximum, the means for correlating and calculating coupled to the means for decimating; e. first means for determining if the maximum exceeds a first predetermined threshold and reporting noise present if the predetermined threshold is not exceeded, the means for determining coupled to the means for correlating and calculating; f. means for performing a Fast Fourier Transform analysis of the decimated signal and identifying a first, a second and a third largest frequency-domain maxima, the means for performing coupled to the first means for determining; g. second means for determining if both the first and second largest frequency-domain maxima exceed a second predetermined threshold and reporting speech present if either the first or the second largest frequency-domain maxima exceed the second predetermined threshold, the second means for determining coupled to the means for performing a Fast Fourier Transform; and h. third means for determining whether a ratio of the first largest to the third largest frequency-domain maxima exceeds a third predetermined value and reporting a tone present if the ratio is larger than the third predetermined value, the third means for determining coupled to the second means for determining. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. An apparatus for performing real-time recognition of speech and call-progression tones from electrical energy on a signal line comprising:
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a. means for receiving a first plurality of digitized signal samples representing electrical energy on a signal line; b. means for attenuating the digitized signal and forming a filtered signal, the means for attenuating coupled to the means for receiving; and c. microprocessor means for determining whether the electrical energy represents a tone, noise or speech coupled to the means for receiving and the means for attenuating, the microprocessor means comprising; i. means for decimating the filtered signal and forming a decimated signal; ii. means for correlating a second plurality of neighboring portions of the decimated signal and calculating a maximum; iii. first means for determining if the maximum exceeds a first predetermined threshold and reporting noise present if the predetermined threshold is not exceeded; iv. means for performing a Fast Fourier Transform analysis of the decimated signal and identifying a first, a second and a third largest frequency-domain maxima; v. second means for determining if both the first and second largest frequency-domain maxima exceed a second predetermined threshold and reporting speech present if either the first or the second largest frequency-domain maxima exceed the second predetermined threshold; and vi. third means for determining whether a ratio of the first largest to the third largest frequency-domain maxima exceeds a third predetermined value and reporting a tone present if the ratio is larger than the third predetermined value. - View Dependent Claims (11, 12, 13)
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Specification