Low bit rate speech signal transmitting system using an analyzer and

Abstract

In a speech signal encoding system comprising an analyzer and a synthesizer, the analyzer is supplied with an input analog signal to preliminarily select a sequence of digital signals within an analysis frame, to extract a sequence of excitation pulses, from the analysis frame which is divided into a plurality of time intervals each of which is subdivided into a plurality of phases, correlations are calculated between autocorrelations of impulse responses within the analysis frame and cross correlations between the digital signals and the impulse responses to detect, by a maximum similarity series searching circuit, the sequence of the excitation pulses which has a maximum similarity between the autocorrelation coefficients and the cross correlations. The excitation pulses appear at an equidistant time interval and an identical amplitude and have a selected one of the phases and variable polarities. The excitation pulses are sent to the synthesizer together with a phase signal representative of the selected phase, an amplitude signal determined by the analyzer, and a sequence of LPC parameters calculated in relation to the analysis frame.