A REALIZABLE PARAUNITARY PERFECT RECONSTRUCTION QMF BANK BASED ON IIRFILTERS

In this paper, we address the problem of realizing a paraunitary perfe ct reconstruction quadrature mirror filter bank based on IIR filters. The bank is devoted to the analysis of transient phenomena, in particu lar of seismic traces from which the information of the arrival times of the incoming phases must be extracted. We have shown recently (Lo P resti and Olmo, To be submitted) that this task requires the realizati on of highly selective filter banks, which makes it necessary to resor t to IIR solutions. The details of the implementation of such a filter bank are addressed, with particular emphasis on the border effects wh ich arise due to the presence of noncausal fillers. Solutions which av oid both the signal scattering and the initial condition errors are pr oposed for the particular class of signals at hand, namely vanishing o nes, The addition of zeros at the head and tail of the sequence can ef fectively combat distorsion in the recovered signal, and at the same t ime does not affect the coefficients of the decomposition. A signal su pport enlargement can be tolerated for the application at hand, which is focused on the data analysis. Rules are given in order to evaluate the number of zeros to be added, as a function of the employed filters . The results in terms of the reconstruction error are rather satisfac tory for the considered class of signals.