High-frequency bandwidth extension in the time domain
First Claim
Patent Images
1. A system that extends the high-frequency spectrum of a narrowband audio signal in the time domain comprising:
- an interface configured to receive a narrowband audio signal;
a controller that extends the harmonics of vowels by introducing a non linearity in the received narrowband audio signal in the time domain; and
a random noise generator that generates consonants by introducing random-noise in the received narrowband audio signal in the time domain,where the controller comprises a squaring circuit that squares a segment of the narrowband audio signal.
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Abstract
A system extends the high-frequency spectrum of a narrow band audio signal in the time domain. The system extends the harmonics of vowels by introducing a non linearity in a narrow band signal. Extended consonants are generated by a random-noise generator. The system differentiates the vowels from the consonants by exploiting predetermined features of a speech signal.
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Citations
18 Claims
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1. A system that extends the high-frequency spectrum of a narrowband audio signal in the time domain comprising:
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an interface configured to receive a narrowband audio signal; a controller that extends the harmonics of vowels by introducing a non linearity in the received narrowband audio signal in the time domain; and a random noise generator that generates consonants by introducing random-noise in the received narrowband audio signal in the time domain, where the controller comprises a squaring circuit that squares a segment of the narrowband audio signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method that extends a high-frequency spectrum of a narrowband signal comprising:
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determining if a portion of a signal represents a vowel or a consonant; generating a first portion of a high frequency spectrum in a time domain by squaring a portion of a narrow band signal if the that portion of the narrowband signal represents the vowel; generating a second portion of the high frequency spectrum in the time domain by generating a random signal if the portion of the narrowband signal represents the consonant; and filtering the generated high frequency signals to adjust spectral shapes and magnitude. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A system that extends the high-frequency spectrum of a narrowband audio signal in the time domain comprising:
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an interface configured to receive a narrowband audio signal; a controller that extends the harmonics of vowels by introducing a non linearity in the received narrowband audio signal in the time domain; a random noise generator that generates consonants by introducing random-noise in the received narrowband audio signal in the time domain, a plurality of filters that pass a portion of frequencies of the non-linearity generated by the controller and the random-noise generated by the random-noise generator, respectively, a plurality of amplifiers that increase magnitudes of the non-linearity and random-noise; a plurality of mixers that select a portion of the non-linearity generated by the controller and a portion of the random-noise generated by the random-noise generator; a first summing circuit that sums the portion of the non-linearity generated by the controller and the portion of the random-noise generated by the random-noise generator; a second summing circuit that sums the portion of the combined non-linearity and the random-noise with the narrowband audio signal a first adaptive filter configured to dampen a background noise detected in an upper frequency of the second summed signal; and a second adaptive filter configured to vary the spectral shape of a portion of the second summed signal, where the controller comprises a squaring circuit that squares a segment of the narrowband audio signal.
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Specification