Arrangement for filtering compressed pulse-code-modulated signals
AssigneeU.S. Philips Corporation
InventorLudwig D. J. Eggermont
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Abstract
Digital filter for filtering nonuniformly quantized pulse code-modulated signals formed by a sequence of code words each comprising a segment number s(i) and a mantissa number m(i). This digital filter comprises a modifying device to which the mantissa numbers m(i) are applied for generating modified mantissa numbers E(i). The numbers E(i) are each multiplied by the magnitude of a filter coefficient, for generating first product numbers z.sub.1 (i). Thereafter these numbers z.sub.1 (i) are each multiplied by a number 2.sup.B(i), B(i) being either equal to s(i) or equal to s(i)-1, so that second product numbers z.sub.2 (i) are obtained which are applied to an accumulator.
Claims3
A digital filter arrangement for filtering non-uniformly quantised pulse code-modulated signals formed by a sequence of code groups x(i) each comprising a segment number s(i) and a mantissa number m(i), which digital filter arrangement comprises:
- a first storage medium comprising first storage locations for storing the segment numbers s(i-k), second storage locations for storing the mantissa numbers m(i-k) of a given plurality of N consecutive code groups x(i-k), where k=0, 1, 2, . . . N-1 and i= . . . -3, -2, 0, 1, 2, 3, . . . , and outputs for sequentially supplying the stored code groups;
- a second storage medium for storing the absolute magnitudes .vertline.a(k).vertline. of N filter coefficients a(k) and having outputs for sequentially supplying the stored absolute magnitudes;
- means coupled to the second storage location of said first storage medium for modifying the mantissa numbers m(i-k) and for generating modified mantissa numbers E(i-k);
- first multiplying means connected to the modifying means and coupled to the second storage medium for generating first product numbers z.sub.1 (i-k)=E(i-k).vertline.a(k).vertline.;
- second multiplying means connected to the first multiplying means;
- means for coupling the second multiplying means to the output of the first storage locations of said first storage medium;
- and
- accumulating means coupled to the second multiplying means for accumulating the product formed in said second multiplying means.
An arrangement for filtering non-uniformly quantised pulse code-modulated signals formed by a sequence of code groups x(i) each comprising a segment number s(i) and a mantissa number m(i), wherein said arrangement comprises:
- a first storage medium comprising first storage locations for storing the segment numbers s(i-k), second storage locations for storing the mantissa numbers m(i-k) of a plurality of N consecutive code groups x(i-k) where k=0, 1, 2, . . . N-1 and i= . . . -3, -2, -1, 1, 2, 3, . . . , and outputs for sequentially supply stored code groups;
- a second storage medium for storing N sets of numbers F(k,j), each set characterizing the magnitude .vertline.a(k).vertline. of a filter coefficient a(k), said second storage medium having outputs for supplying the stored magnitudes;
- means connected to the output of the second storage locations of said first storage medium for modifying the mantissa numbers m(i-k) and for generating modified mantissa numbers E(i-k);
- adding means coupled to the output of the second storage medium for sequentially generating sum numbers D(k-j);
- means for coupling the adder means to the output of first storage locations of said first storage medium;
- multiplying means coupled to said adding means and the modifying means for sequentially generating product numbers z.sub.2 (i-k) [=E(i-k).multidot.2.sup.D(k,j) ];
- and
- means for accumulating the product numbers z.sub.2 (i-k).
Dependencies are inferred from the claim text.