Design of Two-Dimensional Periodically Time-Variant Digital Filters

Toshiyuki YOSHIDA
Yoshinori SAKAI

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E80-A    No.8    pp.1453-1459
Publication Date: 1997/08/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Digital Signal Processing)
digital filters,  multidimensional filters,  time-variant filters,  

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This paper discusses a design method for two-dimensional (2-D) periodically time-variant digital filters (PTVDFs) whose filter coefficients vary periodically. First, 2-D periodicities for a variation of filter cefficients are considered, from which two and four-phase variations of coefficients are shown to be suitable for practical applications. Then, the input-output relation (transfer function) for 2-D separable-denominator (SD) PTV DFs is derived, which results in a linear combination of the baseband input signal and its modulated versions. Finally, in order ro approximate given filter specifications, the structure for 2-D SD PTV DFs is given and a design method is proposed. It is shown that, compared with the 2-D SD time-invariant DFs, approximation error can be reduced with the proposed SD PTV DFs.