Pitch detection for use in a predictive speech coder

摘要

A pitch data detecting means to be used to adjust long term predictive means in a pulse excitation speech coder. A residual signal r(n) is first derived from the speech signal s(n) through short term filtering then r(n) is processed to provide a prediction error signal e(n) to be pulse excitation encoded. The generation of e(n) involves predicting a residual through Long Term Prediction operations including measuring a pitch related factor M, through a dual steps process with first step providing a coarse M value through peak clipping and sign transition detection, and then second step for adjusting said M to a finer value through autocorrelations operating about the roughly spaced peaks.