Finite Impulse Response Filters

A finite impulse response (FIR) filter has a unit impulse response that has a limited number of terms, as opposed to an infinite impulse response (IIR) filter which produces an infinite number of output terms when a unit impulse is applied to its input. FIR filters are generally realized nonrecursively, which means that there is no feedback involved in computation of the output data. The output of the filter depends only on the present and past inputs. This quality has several important implications for digital filter design and applications. This chapter discusses several FIR filters typically used for real-time ECG processing, and also gives an overview of some general FIR design techniques.