Generalized approach to sampling rate alteration in wave digital filters

Generalized arrangements (wave-flow diagrams) for sampling rate alteration in wave digital filters (WDFs) are proposed and analyzed. By this new approach, the number of degrees of freedom of the resulting so-called multirate WDF is not reduced in relation to that of the reference circuit. Advantages of the earlier multirate WDF´s, such as improved loss performake for a given filter structure, increased dynamic range, and low passband sensitivity for coefficients, are preserved. Necessary and sufficient realiiability conditions for the generalized multirate WDF´s are also presented. It is assumed that the reference filter is lossless, reciprocal, and rational in its complex frequency 4. An example of a fifth-order WDF for sampling rate increase is given.