SYSTEME DE TRANSMISSION DE LA PAROLE

摘要

1347794 Speech transmission STANDARD TELEPHONES & CABLES Ltd 4 Nov 1971 51276/71 Heading H4R In a speech transmission system formant frequency peaks are reduced in the signal spectrum to be transmitted, e.g. using a self adaptive filter, and are reinserted after transmission, using at the receiver only the transmitted residual signal. As described with respect to Fig. 1 a self adaptive transversal filter 3 is connected in feed forward configuration with the filter target signal equal to the input signal so that the output signal from the subtractor is the input speech signal with formani frequency resonances reduced. A similar filter 4 connected in feedback configuration restores the original speech at the receiver. The trans mission link can include a p.c.m. coder or delta modulator in which case the receiver circuit tends to emphasize quantizing noise. A modified circuit, Fig. 4, in which a decoder 11 provides the input to the coder from the coded output to feed back the quantizing noise, reduces the quantizing noise in the output.