Digital Filters

In this chapter digital filters are introduced. While an analog filter is implemented in hardware, a digital filter is implemented in software; it is a computer algorithm. Hence, this chapter works with sampled signals and the objective is to do the same thing with sampled signals as we did with analog signals (non-sampled signals) in Chap. 9 , but instead of using hardware, software algorithms are presented that do the filtering. First, discrete-time convolution is defined, but the focus is on the FIR and IIR filters, which are the two most common digital filter algorithms for sampled signals. The reader will learn two design techniques for digital filters; the inverse Fourier transform method and the bilinear transformation method.