[HN Gopher] Why is it a bad idea to filter by zeroing out FFT bins?
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       Why is it a bad idea to filter by zeroing out FFT bins?
        
       Author : bcaa7f3a8bbc
       Score  : 17 points
       Date   : 2021-05-09 17:19 UTC (5 hours ago)
        
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       | jschveibinz wrote:
       | While it's not necessarily a "bad idea" depending upon your
       | application, you may be able to do "better" in the side lobes
       | using masking functions (windows) other than rectangles, which is
       | what zeroing is. See hanning, hamming, etc.
        
         | Junk_Collector wrote:
         | Said another way, you're making a filter. Zeroing out FFT bins
         | is a brickwall filter. Brickwall filters have poor frequency
         | and amplitude accuracy if you are trying to preserve the signal
         | in the passband. A Flattop filter will give maximum amplitude
         | accuracy, a gaussian filter will give good amplitude and
         | excellent frequency accuracy. Other filter types can be
         | implemented to require less computation for resource
         | constrained systems under certain circumstances. Zeroing is the
         | simplest filter to implement in code, but it's performance is
         | essentially the worst from a signals point of view.
        
       | im3w1l wrote:
       | How does a brickwall filter affect the following things?
       | 
       | A tone played for a fixed time, a glissando, vibrato, a pure tone
       | that lies between two frequency bins?
        
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       (page generated 2021-05-09 23:02 UTC)