Lowpass Digital Filter Example
A two-pole Butterworth filter is designed using the method illustrated in Example 12.3. The cutoff frequency is 1000 hz and the sampling period is T=1/10000. The resulting filter is shown below. The red circles show the values of |H| at the digital frequencies corresponding the analog frequencies of 400 hz and 4000 hz, which are the components in x(t). (Recall that .)
The m-file that generated these figures can be downloaded from here.