Difference Equation

We first write the comb filter specification in a more ``mathematical'' form as a digital filter difference equation:

$$y(n) = x(n) + g_1\, x(n-M_1) - g_2\, y(n-M_2), \protect$$ (4.1)

where $x(n)$ denotes the $n$th sample of the input signal, $y(n)$ is the output at time $n$, and $g_1$ and $g_2$ denote the feedforward and feedback coefficients, respectively. The signal flow graph is shown in Fig.3.1.