14.1 INTRODUCTION

Multirate digital processing systems are important due to the numerous applications in which efficient translations among various sampling frequencies are needed. An important application of multirate digital filters is to implement the discrete wavelet transform. Decimators and interpolators are the most basic elements of such systems. They have also found applications in sub-band coding and analog-to-digital (A/D) conversion [89–93]. Particular interest is nowadays focused on the implementation of multirate filters for real-time applications.

Multirate systems rely on the use of decimators and interpolators. A decimator accepts a high-rate input signal and produces a low-rate output signal. An interpolator accepts a low-rate input signal and produces a high-rate output signal. We discuss in this chapter how to design multithreaded systems that implement decimators and interpolators.