### 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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