High Low Pass Filter using Fast Fourier Transform

Question

Hello guys Do you know how to implement High Low pass filter using FFT? Thx a lot

Wizzer King · Answer

The basic Principles are Easy Perform FFT For high Pass Filter Set all frequencies in the data to 0 below the cutoff frequency For Low Pass Filter set all Frequency data in teh FFT above teh Cutoff Frequency to 0 Convert From FFT to Time Domain Data The Time Domain Data is Now Filtered FFTW is a C library you can wrap in C# otherwise here is a web site that I found useful http://www.sdss.jhu.edu/~tamas/bytes/fftwcsharp.html The FFTW site also has pointers to C# at two other places

High , Low Pass Filter using Fast Fourier Transform