METHOD OF TRANSMITTING, AT LOW RATE, BY CELP CODING OF A SPEECH SIGNAL AND CORRESPONDING SYSTEM.

摘要

The invention relates to a method for transmitting a low bit rate digital speech signal. BR/ The coding is performed by code-excited linear prediction to generate a code signal, a waveform being represented by an initial vector (O) of dimension L, from a synthesis filter by a shape reference waveform selected from a reference vector dictionary (v), on min minimum difference criterion || x - Hv || 2, x representing a target vector by perceptual weighting of the initial vector (O). A dictionary (Y) factorized as a product of base vectors yi of n-ary shape, corrected by a gamma scaling factor of distribution of the excitation energy, and a dictionary G (y) of gains gk, are set to represent the reference vector dictionary (v), vk, i = gk.gammai.yi. The criterion is established by calculating C (gk, gammai.yi) = 2gk - gk2 || H.gammai.yi || 2 formed of scalar products and perceptual energies. The initial vector (O) is assigned the optimal reference vector vk *, i * = gk * .gammai * .yi * represented by the only index values k *, i *. BR/ Application to coding and transmission of low-rate speech by ternary or n-ary vectors.