See also: Fourier transform, Linear filters

IIR filter design tool

This is the beta version of an IIR filter design library. It can design three kinds of filters:

butterworthIIRFilter	Maximally flat passband, monotonic everywhere.
chebyshev1IIRFilter	Equiripple in the passband, monotonic in the stopband.
chebyshev2IIRFilter	Monotonic in the passband, equiripple in the stopband.

import signals.filters.iir-1;

IIR filter design

import signals.filters.iir-1;

my_filter = IIRFilter (
	8, // filter order
	1 dB, // passband ripple
	-60 dB, // stopband attenuation
	"", // band configuration
	[25 Hz], // cutting frequency
	[25 Hz, 50 Hz], // cutting frequencies
	150 Hz // sampling frequency
)
my_filter.plot()
Design Filter

All IIR filter design functions return ZeroPoleGain structures.

Visualization

my_filter.plotZerosPoles() Plot my_filter.plotPhase() Plot my_filter.plotAmplitude() Plot my_filter.plotImpulseResponse() Plot

Testing the designed filter

input = [! zeros(100,1), ones(100,1), zeros(100,1), ones(100,1) !];
output = my_filter.filter(input);
chart().curve(input).curve(output)
Test Filter

Implementation

my_filter.getImplementationDetails()