Filter Order

The maximum delay, in samples, used in creating each output sample is called the order of the filter. In the difference-equation representation, the order is the larger of and in Eq.(5.1). For example, specifies a particular second-order filter. If and in Eq.(5.1) are constrained to be finite (which is, of course, necessary in practice), then Eq.(5.1) represents the class of all finite-order causal LTI digital filters.

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written by 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.