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What do the values of a FFT output means?
I'm using AudioKit's FFT algorithm (framework written for Swift) and when I fft the AudioNode (the microphone sound), it gives me a variable containing the fft data. It's a variable of 512 positions (0 to 511).
When I do it, it gives me veeeery small results, like 0.00004231 or even 2.41233e-7, sometimes 2.41233e-12. What do these values means?
What I think:
index 0: 0 - x Hz
1: x - 2x Hz
2: 2x- 3x Hz
::
::
and so on...
Each array has the Amplitude value of that position.
Am I right? If no, please explain me. It will help me a lot.
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go to model configuration parameter and select Data Import/Export. Untick the Single simulation output and click on Apply. double tap the scope and go to Logging and select Log data to the workspace and select Structure with Time and click on Apply. double tap Powergui and select FFT Analysis.
These frequencies actually represent the frequencies of the two sine waves which generated the signal. The output of the Fourier transform is nothing more than a frequency domain view of the original time domain signal.
The output of the FFT is a complex vector containing information about the frequency content of the signal. The magnitude tells you the strength of the frequency components relative to other components. The phase tells you how all the frequency components align in time.
The Fourier Transform maps a signal from the time domain to the frequency domain. As such, each FFT sample measures that given frequency intensity in the original signal.
For instance, fft[2] indicates how strong frequency 2 hz is in the original signal. Keep in mind there might be some scaling in the fft array returned by AudioKit, so please check the actual frequency range covered by those 512 samples.
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