Butterwordth filter


The Butterworth filter is a widely used filter algorithm in digital signal processing. It has a constant transfer function in the passband and stopband. It’s transfer function decreases monotone for an increasing f and its slope is -20*N dB/decade.

By default this solver uses an order = 3. But the order can be choosen between 2 and 5. The sampling frequency is set to 10 kHz by default and 1000 samples are used. That gives a minimum frequency of 10 Hz that can be simulated .

Pressing the “run” button computes the filter parameters and simulates a sinus signal of "Test frequency" Hz. The green curve is the unfiltered input signal, the blue one is the filtered output. The checkbox "Highpass" selects high or low pass behaviour.

At the very bottom the filterparameters of the transfer function

Butterworth



in the z plane are displayed.

For the detailed description of the filter algorithm see Butterworth filter



Butterworth filter

Order:
Cut off frequency Hz Sample frequency Hz Test frequency Hz




Demo Project digital Butterworth filter in Java script

  • Butterworth filter