dft

DSP - Filtering frequencies using DFT

I'm trying to implement a DFT-based 8-band equalizer for the sole purpose of learning. To prove that my DFT implementation works I fed an audio signal, analyzed it and then resynthesized it again with no modifications made to the frequency spectrum. So far so good. I'm using the so-called 'standard way of calculating the DFT' which is b...

DSP - Filtering in the frequency domain via FFT

I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this d...

Recommendations for good description of Fourier Theory & DFT?

Does anyone have a favorite "go-to" paper, web site, etc., for explaining the basics behind Fourier theory / discrete Fourier transforms? I am not overly inclined mathematically, and while I know this particular domain requires some math skills I'm hoping for documentation that eases me into it so I have some understanding of intent by ...

any rules of thumb how to smooth FFT spectrum to prevent artifacts when hand-tweaking?

Hi, I've got a FFT magnitude spectrum and I want to create a filter from it that selectively passes periodic noise sources (e.g. sinewave spurs) and zero's out the frequency bins associated with the random background noise. I understand sharp transitions in the freq domain will create ringing artifacts once this filter is IFFT back to t...