Sprachkodierung mittels Analyse durch Synthese

摘要

The method involves using a digitiser (18) to form a speech signal into successive frames divided into typically 4 subframes of 40 samples of 16 bits. A coder (16) delivers a binary sequence at a substantially slower rate to a channel encoder (22), introducing error detection and/or correction bits. Each frame is analysed by short-term linear prediction (26) to determine coeffts. of a short-term synthesis filter. For each subframe, an excitation sequence is determined which after filtering produces a synthetic signal representing the speech. The subframe is divided into segments corresp. to pulses of stochastic excitation (40), and the positions of these pulses are found so that there is at most one in each segment.