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| blog:2019:0225_fft_scaling_factor [2019/02/26 17:03] – davek | blog:2019:0225_fft_scaling_factor [2019/02/26 17:03] – davek |
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| ====== FFT scaling factor ====== | ====== FFT scaling factor ====== |
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| What's often confusing about the [[https://en.wikipedia.org/wiki/Fast_Fourier_transform#Definition|FFT]] is that the transform seems to have numbers that are too big. Let's call this the "[[https://www.google.com/search?q=fft+scale+factor|FFT scale factor]]" problem (it's a reasonable google search). The frequency domain seems to have much more energy (much higher values) than one might expect from the time-domain waveform from which it originated. | What's often confusing about the [[https://en.wikipedia.org/wiki/Fast_Fourier_transform#Definition|FFT]] is that the transform seems to have numbers that are too big. Let's call this the "FFT scale factor" problem (it's a reasonable [[https://www.google.com/search?q=fft+scale+factor|google search]]). The frequency domain seems to have much more energy (much higher values) than one might expect from the time-domain waveform from which it originated. |
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| When trying to understand this, the uninitiated user will google something like "FFT scale factor" and get lots of really good explanations about **how** the math produces values that are N times larger than one might expect, N being the size of the FFT. | When trying to understand this, the uninitiated user will google something like "FFT scale factor" and get lots of really good explanations about **how** the math produces values that are N times larger than one might expect, N being the size of the FFT. |
