Speech coder using an orthogonal search and an orthogonal search method

摘要

A code excited linear prediction speech decoder includes an adaptive codebook configured to generate an adaptive code vector. The decoder also includes a random codebook configured to generate a random code vector. The decoder also includes a synthesis filter that receives a signal based on said adaptive code vector and said random code vector, and that is configured to perform linear prediction coefficient synthesis on said signal. The random codebook includes a pulse vector providing system configured to provide a pulse vector having a signed unit pulse. The random codebook also includes a comparing system configured to compare a value of adaptive codebook gain with a preset threshold value. The random codebook further includes a selecting system configured to select a dispersion pattern from a plurality of dispersion patterns stored in a memory in accordance with a result of said comparison. The random codebook additionally includes a generating system configured to generate said dispersed vector by convoluting said pulse vector and said selected dispersion pattern.