ENCODER CAPABLE OF REMOVING INTERACTION BETWEEN ADJACENT FRAMES

摘要

In an encoder for encoding an input signal (AA) into a sequence of excitation pulses (GG) with reference to an autocorrelation signal (DD) and a cross-correlation signal (CC) derived from the input signal, a cross-correla-tion controller (40) controls the cross-correlation signal in response to the autocorrelation signal and the excitation pulse sequence by producing a control signal (HH). Both of the cross-correlation and the autocorrelation signals are concerned with a current frame of the input signal and a part of the following frame. The control signal appears in the following frame to be subtracted from the cross-correlation signal in a subtractor (31) and to modify the cross-correlation signal into an adjusted cross-correlation signal (EE). Although the adjusted cross-correlation signal lasts for the current frame and the part of the following frame, an excitation pulse generator (32) produces the excitation pulses only within the current frame.