Symmetrical filtering apparatus and method therefor

Details Symmetrical filtering apparatus and method therefor Symmetrical filtering apparatus and method therefor

1995-10-27

1998-04-07

Malzahn, David H.

Boots, shoes, and leggings

36472401, G06F 1710

Patent

active

057372543

ABSTRACT:
A data processing system (10) implements a symmetrical filtering function about the unity gain line using a single filter (33). The data processing system (10) includes a bus (12), an I/O port (12), memory (16), and a processor (18). The I/O port (12) receives filter control parameters (20) and receives and transmits digitized data. The processor receives the filter control parameters (20) and calculates filter coefficients (44, 48, 52). The processor (18) implements the single stage filter (33) based upon the filter coefficients (44, 48, 52) to filter the digitized input data (22) and produce filtered digitized data (24). The single stage filter (33) may include a band pass, high pass, or low pass function. The single stage filtering function (33) produces a filtering function that is symmetrical about the unity gain line. Variable Q operation of the data processing system (10) allows Q of the filtering function to vary with boost/cut level (34). A method (150), a graphic equalizer (200), and digital telephone (250) also incorporate the symmetrical filtering function.

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patent: 5282252 (1994-01-01), Orban
patent: 5388062 (1995-02-01), Knutson
"Design of a Digital Biquadratic Peaking or Notch Filter for Digital Audio Equalization" by Stanley A. White. Journal of Audio Engineering Society, vol. 34, No. 6, 1986. pp. 479-483.
J. Lane et al., Implementing IIR/FIR Filters with Motorola's DSP56000/DSP6001, APR7/D, Rev2 Sect. 2-"Second-Order Direct-Form IIR Digital Filter Sections," 1993, pp. 2.1-2.27.
Hillman et al., ICASSP 1989, "Real-Time Determination of IIR Coefficients for Cascaded Butterworth Filters", Dec. 20, 1988, pp. 1-4.
Lane et al., Computer Music Journal, vol. 14, No. 3, Fall 1990,"Pitch Detection Using a Tunable IIR Filter," pp. 46-59.
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Zudock et al., DSP & Multimedia Technology, "Software Design Tools for the Motorola DSP56000," Nov. 1994, pp. 54-65.

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