Design and implementation of efficient resampling filters using polyphase recursive all-pass filters

Computationally efficient resampling filters are formed from sets of recursive all-pass subfilters operating in a polyphase structure. These subfilters, exhibiting unity magnitude response, have phase shifts which add constructively in the passband(s) and destructively in the stopband(s). The computational burden for these filters is one-fifth to one-tenth that of conventional resampling filters. The primary advantage of these structures is the relatively low workload per output point. A secondary advantage is the low sensitivity to finite arithmetic and the lack of bit growth in internal states. Disadvantages include the nonuniform phase response of the filter, as well as the newness of the idea and the difficulty in determining coefficients for the filter