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FFT:Frequency-Amplitude plot

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Old   May 20, 2019, 22:44
Default FFT:Frequency-Amplitude plot
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liyong
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In the line plotting section, I use the Fast Fourier Transform(FFT) function to deal with cylinder pressure. After click preview FFT, a frequency spectrum figure appears, shown as in attachment. But the amplitude is surprisingly large. The original cylinder pressure is also attached. I think the amplitude is incorrect. the Y-coordinate is not the amplitude so what is that?
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File Type: jpg pressure.jpg (44.1 KB, 12 views)
File Type: jpg prequency-amp.jpg (55.6 KB, 11 views)
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Old   May 24, 2019, 10:54
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Sameera Wijeyakulasuriya
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Hello,

You should carry out the inverse FFT operation to obtain the filtered pressure from this calculator.

Thanks,
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Old   May 25, 2019, 06:19
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Quote:
Originally Posted by SamWijey View Post
Hello,

You should carry out the inverse FFT operation to obtain the filtered pressure from this calculator.

Thanks,
I don't need the filtered pressure, and I just want to attain the frequency- amplitude. I want to know which frequency on which the pressure amplitude is large.
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