Finite Impulse Response Digital Filters

In §5.1 we defined the general difference equation for IIR filters, and a couple of second-order examples were diagrammed in Fig.5.1. In this section, we take a more detailed look at the special case of Finite Impulse Response (FIR) digital filters. In addition to introducing various terminology and practical considerations associated with FIR filters, we'll look at a preview of transfer-function analysis (Chapter 6) for this simple special case.

Figure 5.5 gives the signal flow graph for a general causal FIR filter Such a filter is also called a transversal filter, or a tapped delay line. The implementation shown is classified as a direct-form implementation.

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Subsections

• FIR impulse response
• Convolution Representation of FIR Filters
• The ``Finite'' in FIR
• Causal FIR Filters
• FIR Transfer Function
• FIR Order
• FIR Software Implementations

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About the Author: Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.