[luckyboy]

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?

[SamWijey]

Hello,

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

Thanks,

[luckyboy]

Originally Posted by SamWijey

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.