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Speech coding system

  • US 20020173949A1
  • Filed: 04/04/2002
  • Published: 11/21/2002
  • Est. Priority Date: 04/09/2001
  • Status: Abandoned Application
First Claim
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1. Speech coding system with a speech encoder and a speech decoder cooperating with said speech encoder, the speech encoder comprising a pre-processor and an ADPCM (adaptive differential pulse code modulation) encoder with a quantizer and step-size adaptation means and the speech decoder comprising an ADPCM decoder with similar step-size adaptation means as in the ADPCM encoder and a decoder, and a post-processor, characterized in that the pre-processor is provided with phase-smearing filtering means to smooth the effect of high and/or rapid energy changes at the input of the quantizer and the post-processor is provided with filtering means inverse to said phase-smearing filtering means.

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