Patent ID: 6751277
Filing Date: 2004-06-15
Classification: H03H

Abstract:
A device for filtering an input sequence of digital signals, comprising:(1) a first filtering stage, itself including: (A) a first splitting circuit, provided for subdividing the input sequence into two disjoint sets of samples, comprising respectively the odd samples c0(2n+1) and the even samples c0(2n) of said sequence; (B) a first predicting circuit, provided for generating â€œdetailâ€  coefficients d1(n)=c0(2n+1)âˆ’P1[. . . , c0(2nâˆ’2), c0(2n), c0(2n+2), . . . ], where P1 is a first linear filter and ( . . . , c0(2nâˆ’2), c0(2n), c0(2n+2), . . . ) is the vector containing only the even samples of the input signal; (C) a first updating circuit, provided for generating â€œapproximationâ€  coefficients c1(n)=c0(2n)+U1[. . . , d1(nâˆ’1), d1(n), d1(n+1), . . . ], where U1 is a second linear filter and ( . . . , d1(nâˆ’1), d1(n), d1(n+1), . . . ) is the vector containing the â€œdetailâ€  coefficients; (2) at least a second filtering stage, itself including: (D) a second splitting circuit, provided for subdividing the previously generated â€œapproximationâ€  vector into two disjoint sets of samples, similarly called c1(2n+1) and c1(2n); (E) a second predicting circuit, provided for generating a second level of â€œdetailâ€  coefficients d2(n)=c1(2n+1)âˆ’P2[. . . , c1(2nâˆ’2), c1(2n), c1(2n+2), . . . ], where P2 is a third linear filter and ( . . . , c1(2nâˆ’2), c1(2n), c1(2n+2), . . . ) is the vector of â€œdetailâ€  coefficients of even order resulting from the second splitting operation; (F) a second updating circuit, provided for generating a second set of â€œapproximationâ€  coefficients c2(n)=c1(2n)+U2[ . . . , d2(nâˆ’1), d2(n), d2(n+1), . . . ], where U2 is a fourth linear filter and ( . . . , d2(nâˆ’1), d2(n), d2(n+1), . . . ) is the following vector of â€œdetailâ€  coefficients; characterized in that the first updating circuit and the second predicting circuit are associated within an iterative cross-optimization operation carried out by using the second filter U1 for optimizing the third filter P2 and then said third filter P2 for optimizing said second filter U1.