Nixdorf Computer Ag

Ingo Kunold

A method for filtering digital input signals (e) makes use of all-pass filters of a first-class having the transfer function S1 and all-pass filters of a second-class having the transfer function S2, as well as all-pass filters of higher order, derived therefrom, having the transfer functions S1' and S1' or S2' and S2'. The all-pass filters (10 to 36) are arranged in several stages in such a manner that the number of all-pass filters of higher order for a predetermined filter function is reduced. The output signals (A1 to A8) of the all-pass filters of the lowest order (22 to 36) are combined in a logical operation stage to filter output signals (d1,d8), the respective filter characteristic of which is determined by the logical operation. By the method of this invention, the steps necessary for the filtering can be carried out faster than in the prior art.

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Borchen, Germany

Ingo Kunold