Digital filters with implicit interpolated output

The composition of filtering and interpolation operators is applied to the design of digital filters that, optionally, may perform real-time incommensurate sampling rate conversion. This problem arises in applications where the interpolation times may not be known a priori and are calculated in real time. The proposed interpolating filter operators allow the designer to control the interpolation error through a trade-off between computing time and accuracy. The flexibility of the design is exemplified on a few digital communication applications: square root raised cosine filters for controlling the intersymbol interference through pulse shaping, a bandpass filter, and a differentiator.