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MathCAD FFT Amplitude

thread552-166980

MathCAD FFT Amplitude

MathCAD FFT Amplitude

(OP)
I've been working on this FFT transform and I can't seem to get the right amplitude out.  The frequency is correct, but the amplitude is about 1/3 of what it should be.  The FFT was also done in LabView where it seems to be correct.  Does anyone know if the amplitudes for MathCAD are scaled down by some number?

RE: MathCAD FFT Amplitude

Yes. The scaling is specified in the help.

Even if it wasn't, it is always wise to generate and analyse a unit amplitude test signal when using a new fft routine, I think last time I counted I could think of 4 different scaling conventions.

Cheers

Greg Locock

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RE: MathCAD FFT Amplitude

(OP)
Thanks.  I think I've figured out the problem.  It talks about scaling the FFT by 2, but it wasn't coming out right still.  I think it's de to the ratio of samples to input frequency.  It has to be an integer to come out right.

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