A finite impulse response (FIR) filter is a type of a digital filter. It is 'finite' because its response to an impulse ultimately settles to zero. This is in contrast to infinite impulse response filters which have internal feedback and may continue to respond indefinitely.
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<electronics, DSP> (FIR) A type of digital signalfilter, in which every sample of output is the weighted sum of past and current samples of input, using only some finite number of past samples. (2001-06-06)