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snovotill
Joined: Feb 8, 2013
Posts: 80
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 Posted: Feb 11, 2014 4:09 AM Post subject: Nyquist filter for FFTtransform and FFT2transform |
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Hi Jarek, is it necessary to provide a low-pass filter to prevent aliasing in FFTtransform or FFT2transform?
This might be a stupid question since the number of bins is directly related to the incoming sampling rate,
but I thought I should just make sure and ask since I see other people doing this(probably unnecessarily).
I'm thinking the solution might be just to oversample in the acquisition device and then down-sample it
via a simple TimeTransform moving average, to perhaps 1.5x the highest frequency of interest so I don't
get severe beats between this frequency and the FFT sampling rate. Thanks. Stepan. |
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jarek
Joined: Oct 22, 2007
Posts: 1073
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| Posted: Feb 11, 2014 4:20 AM Post subject: |
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| I am not sure. The implemented FFT elements do not have any input filters. |
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snovotill
Joined: Feb 8, 2013
Posts: 80
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| Posted: Feb 11, 2014 5:29 AM Post subject: |
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Good answer ;o) And I'm pretty sure it's best that way (without any kind of pre-filters).
One would hope that the acquisition device was manufactured to include an alias filter. |
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