Chapter 4 - Digital Filtering

Abstract

One of the fundamental concepts in digital signal processing is the filtering of digital signals. This chapter highlights the structure of digital filters. It also discusses the LabVIEW Digital Filter Design (DFD) toolkit. A finite impulse response (FIR) filter essentially operates on current input to generate a current output. The equi-ripple method, which is commonly known as Remez algorithm, is generally used to produce an optimal FIR filter. This method generates a response whose deviation from the desired response is evenly distributed across the passband and stopband. Other design methods include Kaiser window and Dolph-Chebyshev window. However, an infinite impulse response (IIR) filter uses a number of previous outputs as well as a current and a number of previous inputs to generate a current output. Several methods, which are widely used to design IIR filters, include Butterworth, Chebyshev, Inverse Chebyshev, and elliptic methods. FIR filters require less precision and are computationally more stable than IIR filters. In context to design toolkit, LabVIEW DFD toolkit provides various tools for the design, analysis and simulation of digital filters.