Analysis-by-synthesis 2,4 kbps linear predictive speech codec

A linear predictive speech codec arrangement for performing a closed loop analysis-by-synthesis operation, comprising:

• an excitation model means for generating a plurality of excitation signals comprising voiced excitation generator means in the form of a first order pitch synthesizer for providing a plurality of possible voiced excitation signals for use as an excitation signal;
• and Gaussian noise generator means in the form of a codebook for providing a plurality of possible random sequences for use as an excitation signal, wherein said voiced excitation generator means and said gaussian noise generator means are provided in parallel arrangement;
• sequencing means, coupled to an output of said voiced excitation generator means and said Gaussian noise generator means, for providing all possible pulse trains and random sequences in sequence as possible excitation signals;
• spectrum synthesizer means, coupled to said sequencing means, for providing reconstructed speech generation in response to each of said plurality of excitation signals;
• distortion analyzer means, coupled to an output of said spectrum synthesizer means, for comparing said reconstructed speech with original speech, and providing a distortion analysis signal for each of said excitation signals;
• and
• means for comparing the distortion analysis signal for each of said excitation signals and selecting one of said possible random sequences, or selecting a pitch value and pitch filter coefficient of said first order pitch synthesizer so as to provide optimal reconstructed speech.

A linear predictive speech codec arrangement for performing a closed loop analysis-by-synthesis operation, comprising:

• an excitation model means for generating a plurality of excitation signals comprising voiced excitation generator means in the form of a first order pitch synthesizer for providing a plurality of possible voice excitation signals for use as an excitation signal;
• and Gaussian noise generator means in the form of a codebook for providing a plurality of possible random sequences for use as an excitation signal, wherein said voice excitation generator means and said Gaussian noise generator means are provided in parallel arrangement;
• sequencing means, coupled to an output of said voiced excitation generator means and said Gaussian noise generator means, for providing all possible pulse trains and random sequences in sequence as possible excitation signals;
• spectrum synthesizer means, coupled to said sequencing means, for providing reconstructed speech generation in response to each of said plurality of excitation signals;
• distortion analyzer means, coupled to an output of said spectrum synthesizer means, for comparing said reconstructed speech with original speech, and providing a distortion analysis signal for each of said excitation signals;
• and
• means for comparing the distortion analysis signal for each of said excitation signals and selecting one of said possible random sequences and a pitch value and pitch filter coefficient of said first order pitch synthesizer, and computing a summation of excitation signals according to the selected random sequence and pitch value and pitch filter coefficient so as to provide optimal reconstructed speech.