Multirate recursive digital filters--A general approach and block structures

Multirate filters, in which the input and output sample rates differ, are examined from a general point-of-view with the objective of providing an approach that will permit the filter designer to use input and output sample rates as design variables to be used to optimize system performance. The emphasis is on multirate recursive (IIR) filters that can be computationally efficient when implemented with block structures, with input and output blocks of different lengths. Classes of multirate filters that possess a generalized shift-invariance property, and are susceptible to transfer function analysis, are identified. A general approach to deriving matrix transfer functions for block implementations of multirate filters is derived, and a general method for obtaining state-space realizations of the matrix transfer function is presented.