FFT Windowing 
FFT Windowing 
Jun 5 2003, 17:42
Post
#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, 21:19
Post
#2


Group: Members Posts: 158 Joined: 30August 02 Member No.: 3236 
A frequency bin is simply an FFT output value which represents a specific frequency. If you perform, for instance, a 16point FFT, you're computing 8 frequency components equally spaced between DC and Nyquist (Fs/2). You now have an 8frequency spectrum analysis of the signal. Frequencies in the source data that fall outside the 8 frequency bins or slots bleed onto adjacent bins. In order to reduce the bleeding and improve resolution, windowing of the source data is used.
http://www.dsptutor.freeuk.com/analyser/gu...ce.html#leakage http://www.bores.com/courses/advanced/wind...ows/10_leak.htm http://www.einsite.net/tmworld/index.asp?...icleid=CA187572 


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