Band extending apparatus and method

  • US 7,684,979 B2
  • Filed: 05/02/2005
  • Issued: 03/23/2010
  • Est. Priority Date: 10/31/2002
  • Status: Active Grant
First Claim
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1. A band extending apparatus comprising:

  • a spectral parameter calculating unit, receiving at least an input signal of a preset frequency band to calculate spectral parameters representing spectral characteristics;

    a noise generating unit for generating a noise signal;

    a coefficient calculating unit for shifting the frequency of said spectral parameters to then find filter coefficients;

    a gain unit for supplying a gain to an output of said noise generating unit;

    a synthesis filter unit for passing an output signal of said gain unit through a synthesis filter, formed using said filter coefficients, to reproduce a signal for band extension;

    means for adding a signal corresponding to said input signal converted in a sampling frequency thereof to an output signal of said synthesis filter unit to generate a band extended signal; and

    a voiced/unvoiced discriminating circuit, receiving said input signal of the preset frequency band, to verify whether the input signal in terms of a frame as a unit is voiced or unvoiced;

    wherein said gain unit includes;

    a gain adjustment unit, receiving voiced/unvoiced discrimination information output from said voiced/unvoiced discriminating circuit, to adjust the gain to be imparted to the output signal of said noise generating circuit, depending on whether said voiced/unvoiced discrimination information indicates voiced or unvoiced; and

    a gain circuit, receiving said gain adjusted by said gain adjustment unit to multiply the output signal of said noise generating unit with said gain to output the resulting signal.

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