METHOD AND DEVICE FOR SPEECH SIGNAL PITCH PERIOD ESTIMATION AND CLASSIFICATION IN DIGITAL SPEECH CODERS

A method and a device for speech signal digital coding are provided where at each frame there is carried out a long-term analysis for estimating pitch period d and a long- term prediction coefficient b and gain G, and an a-priori classification of the signal as active/inactive and, for active signal, as voiced/unvoiced. Period estimation circuits (LT1) compute such period on the basis of a suitably weighted covariance function, and classification circuits (RV) distinguish voiced signals from unvoiced signals by comparing long-term prediction coefficient and gain with frame-by-frame variable thresholds.