A design method for a recursive discrete filter described by difference equation with periodically time-varying coefficients

This paper presents an innovative method to analyze the main characteristics of the recursive first-order periodically linear time varying discrete filter, second-order discrete filter (which is considered as two cascaded first-order filters), and for the recursive arbitrary-order discrete filter in the frequency and z-domains. It is shown that periodically linear time varying discrete filters have the distinguishing features, which give them advantages in some applications in comparison with linear time invariant discrete filters