### The ``Finite'' in FIR

From Eq.(5.7), we can see that the impulse response becomes zero
after time . Therefore, a tapped delay line (Fig.5.5) can
only implement *finite-duration* impulse responses in the sense
that the non-zero portion of the impulse response must be finite.
This is what is meant by the term *finite impulse response*
(FIR). We may say that the impulse response has *finite support*
[52].

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Convolution Representation of FIR Filters