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High-frequency bandwidth extension in the time domain

  • US 8,200,499 B2
  • Filed: 03/18/2011
  • Issued: 06/12/2012
  • Est. Priority Date: 02/23/2007
  • Status: Active Grant
First Claim
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1. A system that extends the high-frequency spectrum of a narrowband audio signal in the time domain:

  • an interface configured to receive a narrowband audio signal;

    a squaring circuit that squares a segment of the narrowband audio signal to extend 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 the frequencies on the non-linearity and the random noise;

    a first amplifier that adjusts an envelope of the filtered portion of the random noise to an estimate of a high pass filtered version of the received narrowband audio signal; and

    a second amplifier that adjusts an envelope of the filtered portion of the non-linearity to a level of an envelope of the high pass filtered version of the received narrowband audio signal.

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