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High fidelity speech encoding for telecommunications systems

  • US 5,228,076 A
  • Filed: 02/08/1991
  • Issued: 07/13/1993
  • Est. Priority Date: 06/12/1989
  • Status: Expired due to Fees
First Claim
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1. A telephone for producing and receiving audible speech sound having no foldover distortion owing to the natural frequency spectrum of vowel sounds and having no lowpass filter, said telephone comprising:

  • a microprocessor;

    first transducer means for producing, transmitting and receiving signals representing audible speech sound; and

    signal processing means coupled to the microprocessor and to the transducer means, for converting said audible speech sound to digital signals having a predetermined data rate, said data rate including a preselected sampling rate and a preselected digitizing rate;

    said preselected sampling rate selected at a rate for no foldover distortion of said vowel sounds and said preselected sampling rate is less than the Nyquist sampling rate of consonant sounds found in said audible speech sound;

    said signal processing means including volume compression means for compressing said audible speech sound;

    said preselected digitizing rate selected for use with said volume compression means for reducing quantization noise;

    said preselected sampling rate and said preselected digitizing rate cooperating to provide high fidelity speech quality;

    said signal processing means further including error correction means for producing digital signals representing error correction code at a preselected rate and for combining said last-mentioned digital signals with said digital signals representing audible speech sound;

    said signal processing means further including conversion means for converting digital signals representing said audible speech sound to speech signals representing said audible speech sound.

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