Interactive Fourier Filter (version 1.5)

Interactive Fourier Filter for time-series signals.

Description

A fourier filter for time-series signals. Version 1.5, May 4, 2007, is calibrated specifically for time-based signals. Does not require the Signal Processing Toolbox. By adjusting the parameters, you can create lowpass, highpass, bandpass, and bandreject (notch) filters with variable cut-off rate. There is an interactive version with sliders that allows you to adjust the filter parameters continuously while observing the effect on your signal dynamically. See:
http://www.wam.umd.edu/~toh/spectrum/InteractiveFourierFilter.htm
for more information. (Thanks to Matthew Jones for the slider function.)

• MATLAB release: MATLAB 6.5 (R13)

[Ali ÖZGÜL]

Code technique and runing interface very good. This program application is smilarly structural dynamic analysis Kalman Filter method.

[Tom O'Haver]

Version 1.3, October 15, 2006, adds some bug fixes. See http://www.wam.umd.edu/~toh/spectrum/InteractiveFourierFilter.htm
 for more infomation

[Diana Glaser]

You don't account for the sampling frequency. Code works only for 1 sample per second signals. You should warn about this.

[Tom O'Haver]

In response to the objection of Diana Glaser, the latest version 1.5 is specifically calibrated for time-based signals.

[y jiang]

 

[Oleksiy Chumak]

Matlab 7.5 gives error when i try to run the function: "Undefined function or method 'range'
Error in ==> RedrawFourierFilter at 45
f=((plotrange-1)./range(xvector));
Is it your function or general function which has disappeared in newer Matlab? Thank you.

[Tom O'Haver]

Sorry about that. "Range" used to be a built-in function in Matlab version 6.5:

function y = range(x)
%RANGE The range is the difference between the maximum and minimum values.
% Y = RANGE(X) calculates the range of the input.
% For matrices RANGE(X) is a vector containing the range for each column.
% Copyright 1993-2002 The MathWorks, Inc.
% $Revision: 2.8 $ $Date: 2002/01/17 21:31:48 $
y = max(x) - min(x);

It's such a simple thing it hardly seems worth the trouble of defining a function, but there it is. I'll define it as a user-defined function in future releases. Thanks for the heads up. Tom

[W Thielicke]

 

[Tom O'Haver]

I've uploaded a new keyboard-operated interactive Fourier filer that works in recent versions of Matlab - tested in 7.8(R2009a). See http://www.mathworks.com/matlabcentral/fileexchange/31646-ifilter-interactive-fourier-filter-function