FFT Windowing 
FFT Windowing 
Jun 5 2003, 17:42
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#1


Group: Members Posts: 97 Joined: 14April 02 Member No.: 1781 
I am in the process of trying to understand FFT analysis as it pertains to audio, and I have come across the concept of FFT windowing. Am I understanding it correctly that the main use of FFT windowing is to get better results in the frequency domain (ex. minimizing Gibbs Phenomenon) ?
It seems that one of the most common window functions used is the Hamming window. If I want to use the Hamming window do I just apply and upward slope from the first sample in my data chunk to the center sample and a downward slope from the center sample to the last sample? (This is what the graph in front of me shows) Or is there an explicit mathematical method I am not aware of? Edit: Is the Hamming window good for complex signals too? (the example I read about had only one frequency involved) This post has been edited by RiskyP: Jun 5 2003, 17:43 


Jun 5 2003, 20:01
Post
#2


Group: Members Posts: 158 Joined: 30August 02 Member No.: 3236 
FFT windowing is required to minimize bin "bleed" or "leakage" that occurs in frequency components that are not related to the sampling rate and fall outside the nearest FFT frequency bin. This naturally occurs in all normal audio. An example of where windowing is not required is a test tone that would be used to measure distortion in a conversion process, where the test tone is related to the sampling rate and falls into one of the FFT's frequency bins.
Your windowing example would be "triangular" windowing (assuming a constant slope). Try this link... http://humanresources.web.cern.ch/humanres...02B_27Feb03.pdf 


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