Design methods for periodically time varying digital filters

A theoretical analysis of periodically time-varying (PTV) filters for use in filter banks for TDM/FDM transmultiplexing is presented. The PTV filter simulates the response of a parallel bank of time-invariant filters with their outputs connected to a rotating switch. This analysis leads to a different equation form for a PTV filter that is closely related to a time-invariant companion filter. Design methods in both the time and frequency domains are described, and results are presented. A 12-channel transmultiplexer requiring 3.24*10/sup 6/ multiplications/s is designed, using filters implemented in a polyphase-type structure.<
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