TRANSMISSION SYSTEM USING DIFFERENTIAL PULSE CODE MODULATION WITH ADAPTIVE PREDICTION

摘要

42 In this transmission system using differential PCM, the local decoder incorporated in the loop of the encoder and the remote decoder comprise identical filters (5) and (15) each constituted by a cascade arrangement of several filtering setions (Fl-FN) of the first and/or of the second order; each section may have one or two controllable coefficients, which are modified at each sampling instant by a modification term which depends upon the product of the difference signal (e) produced in the encoder and the gradient of the differencesignal (e) with respect to the controllable coefficient. When the filtering sections (Fl-FN) are recursive, the gradients are obtained by applying a signal corresponding to the difference signal (e) to identical recursive sections (F'l-F'N). When non-recursive filtering sections (Hl-HL) are used, the gradient calculations sections (H'l-H'L) are recursive with a transfer function inverse to that of the sections (Hl-HL). This system is intended to be used for the transmission of signals in telephone networks.