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 FFT units JoseIlic Junior Member Posts: 2 Threads: 1 Joined: Dec 2020 Institution: University of Concepción 12-10-2020, 02:09 AM Hi there,  I am not quite sure about the units in the Fourier Transform. What does a.u. stand for? The only a.u. that I know of is A.U., astronomical units... But I doubt that they are the same. Thanks for your time and the app! José solid Member Posts: 171 Threads: 17 Joined: Nov 2019 Institution: Université de Bretagne Occidentale 12-10-2020, 11:10 PM Hi José. a.u. - arbitrary units. It is when you do not know well units of the original signal. For example for sound when the microphone is not calibrated. When we know the original signal we may use corresponding units. For example for the accelerometer the unit is m/s², so FFT spectrum should have unit m/s² * s = m/s ... a.u. nevertheless is always valid :o) Jens Noriʇzsɔɥ Senior Member Posts: 498 Threads: 22 Joined: Apr 2020 Institution: RWTH Aachen University 12-11-2020, 12:34 AM Thank you for answering this, Mikhail. Something has apparently stopped me while preparing in answer that has been pretty much along your lines… Fourier transforms are not uniquely defined and may vary by a constant factor, so attributing a definite unit to the result does not make much sense. JoseIlic Junior Member Posts: 2 Threads: 1 Joined: Dec 2020 Institution: University of Concepción 12-11-2020, 02:21 AM Oh! I understand. Thank you for your quick response! Cheers! « Next Oldest | Next Newest »

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