FIR impulse response

The impulse response $h(n)$ is obtained at the output when the input signal is the impulse signal $\delta = [1,0,0,0,\ldots]$ (§5.6). If the $k$ th tap is denoted $b_k$ , then it is obvious from Fig.5.5 that the impulse response signal is given by

$$h(n)\isdef \left\{\begin{array}{ll} 0, & n<0 \\ [5pt] b_n, & 0\leq n\leq M \\ [5pt] 0, & n> M \\ \end{array} \right. \protect$$ (6.6)

In other words, the impulse response simply consists of the tap coefficients, prepended and appended by zeros.