fft vs nufft- scaling

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nathan blanc
nathan blanc on 5 Aug 2022
Commented: nathan blanc on 7 Aug 2022
I tried to do a fast fourier transform to a non-uniformly sampled data using nufft. The order of magnitude of the results was weird so I tried to compare the results of MATLAB's fft example. The results seem identical except for a scaling factor of about 550. see attahced script and attached picture of the results from the script.
where does this order of magnitude difference come from? how should I scale the nufft results? It seems pretty obvious that the nufft is the "problematic one" as the magnitude of the fft is approximatly equal to the multiplier (~0.7, 1) in the original signal.
many thanks
Nathan

Accepted Answer

David Goodmanson
David Goodmanson on 6 Aug 2022
Hi Nathan,
In the fft case you are dividing by N = 1500 and multiplying by 2. For nufft you aren't doing that. Hence the factor of about 750.
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nathan blanc
nathan blanc on 7 Aug 2022
Thanks again David

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