Stability of time variant filters

Michael P. Lamoureux, Safa Ismail, Gary F. Margrave

We report on a project to investigate the stability and boundedness properties of interpolated filters that arise in the design of time variant filters. We observe that IIR filters maintain stability under linear interpolation of their PARCOR coefficients, while FIR filters maintain boundedness under linear interpolation of their direct form coefficients. More accurate interpolation between distant filters require higher order interpolation to be effective.