ANALYTICAL DESIGN OF MULTIDIMENSIONAL RECURSIVE DIGITAL-FILTERS WITH CUBIC SYMMETRY AND CONSTANT GROUP DELAYS

An analytical technique is developed for designing multidimensional (M -D) separable-denominator recursive digital filters that meet, simulta neously, magnitude and phase specifications. A cubic symmetry that exi sts in the M-D frequency response is incorporated into the M-D filter structure. The denominator and the numerator of an M-D transfer functi on are designed separately. The former is used to approximate constant group delays and the latter is used to adjust an overall magnitude re sponse. The filter is analytically designed by solving linear equation s only. This serves to reduce the amount of calculations drastically. The stability of the resulting filter is always guaranteed. Finally, t wo examples are given to illustrate the utility of the proposed techni que.