Posts: 2
Threads: 1
Joined: Dec 2020
Institution: University of Concepción
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
Posts: 171
Threads: 17
Joined: Nov 2019
Institution: Université de Bretagne Occidentale
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)
Posts: 547
Threads: 24
Joined: Apr 2020
Institution: RWTH Aachen University
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.
Posts: 2
Threads: 1
Joined: Dec 2020
Institution: University of Concepción
Oh! I understand. Thank you for your quick response!
Cheers!