Masters Theses

Date of Award

6-1987

Degree Type

Thesis

Degree Name

Master of Science

Major

Electrical Engineering

Major Professor

Bruce W. Bomar

Committee Members

Roy Joseph, Basil Antar

Abstract

FORTRAN computer programs are developed for designing two-dimensional (2-D) circularly symmetric recursive digital filters from a one-dimensional (1-D) lowpass prototype using digital spectral transformations (DST's). The DST technique was employed to take advantage of the readily available 1-D filter design software. Also, the DST design method requires no numerical iteration and is relatively simple to program.

A survey of available DST design techniques is given. A choice is then made from among the various techniques. A detailed discussion of the selected technique is given. This technique and its computer program implementation provide a 2-D lowpass digital filter from the 1-D lowpass prototype. A second computer program then applies two l-D DST's to transform the 2-D lowpass filter to other 2-D filter types (lowpass with a different cut-off contour, highpass. bandpass, and bandstop). Several filter designs are carried out to verify that the filters obtained using this technique have magnitude contours of a proper shape to be of practical use.

The problem of realizing the filters designed is also briefly considered. The design programs are written to output the 2-D filter coefficients in the form needed for realizing the filter using a canonical real-gain Roesser's local state-space structure. This structure was selected because it is suitable for subsequent optimization with respect to finite wordlength effects.

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