Digital filter arrangement for non-uniformly quantized pcm

Abstract

Digital filter for filtering non-uniformly quantised pulse code modulated signals formed by a sequence of code groups x(i), each comprising a polarity bit, a segment number and a mantissa number. This digital filter arrangement comprises a generator which cyclically generates a series of sequentially occurring auxiliary numbers each comprising a polarity bit and an address code; a first storage medium 1 for storing the code groups x(i) and controlled by an address computation circuit 13 to which the auxiliary numbers are applied; a second addressable storage medium 2 to which a segment number s(i-h) a mantissa number m(i-l), supplied by the first storage medium 1, as well as a polarity bit supplied by an exclusive OR-gate 3 are applied as the address code. This polarity bit is derived by gate 3 from the polarity bit p(i-l) of the code groups x(i) and the auxiliary numbers polarity bit. This second storage medium 2 contains positive numbers z.sub.p and negative numbers z.sub.n which represent the expanded values of all possible code groups x(i). A positive number z.sub.p is read from the storage medium 2 if the polarity bit is positive and a negative number is the polarity bit is negative. The numbers read from the storage medium 2 are applied to an accumulator 4 which is coupled to an address code output of the generator 7.