Signal Flow Graph

Figure 3.1 shows the signal flow graph (or system diagram) for the class of digital filters we are considering (digital comb filters). The symbol ``$z^{-M}$'' means a delay of $M$ samples (always an integer here). This notation for a pure delay will make more sense after we derive the filter transfer function in §3.6.

Figure 3.1: signal flow graph for digital filters having difference equations of the form $y(n) = x(n) + g_1\, x(n-M_1) - g_2\, y(n-M_2)$ (digital comb filters).