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IIR Example

Figure 5.8 plots an IIR filter example for the filter

$\displaystyle y(n) = x(n) + 0.99\, y(n-1).

The previous matlab is modified as follows:
      Nh = 300; % APPROXIMATE filter length (visually in plot)
      B = 1; A = [1 -0.99]; % One-pole recursive example
      ...       % otherwise as above for the FIR example
The decay time for this recursive filter was arbitrarily marked at 300 samples (about three time-constants of decay).

Figure 5.8: Example transient, steady-state, and decay responses for an IIR ``one-pole'' filter driven by a gated sinusoid.
Input Signal

Filter Output Signal

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Transient and Steady-State Signals
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FIR Example