CHAPTER 5 Finite Impulse Response (FIR) Filters This chapter focuses on the workhorse of DSP: the finite infinite response (FIR) filter. We discuss three main topics. First, we talk about the structure of an FIR filter, how to build one, and some of its properties. Next, we show how, given the filter coefficients, to compute the frequency response of the filter (normally, this is done with software, but we can gain insight by understanding how to perform this procedure). Last, we show a method to compute coefficients to meet a given frequency response. This last step is what is commonly required of a DSP designer: to find the number and value of filter coefficients required for frequency response required by the application. Again, this procedure is normally performed with software, but we need to gain insight as to what is involved. Filter design is a process in which we cannot have everything, and compromise is necessary. To use software tools to design filters, we need to understand what the different trade-offs are and how they interact. 5.1 FIR Filter Construction