The block diagram in Figure 32.1 represents the canonical form for an Mth order finite-impulse response (FIR) digital filter in that the diagram is a direct implementation of the filter’s defining difference equation:
Figure 32.1. Block diagram for FIR filter
Examination of the equation reveals that the filter’s output at time n is simply a weighted sum of the inputs at times n – M through n. The notation used in Eq. (32.1) is consistent with the notation used in the difference equation ...