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FFT on a series of data sets

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[quote][i]Originally posted by espenhjo[/i]
[br]Hi all!
I need to do an FFT on a series of datasets, all having the same structure. For this have I tried to use the LabTalk script in the help file. The thing is that when I use this I don't get the correct FFT as when I select the FFT manually from the analysis menu in Origin. I use exactly the same parameters manually as in this script:

loop (i,1,9) {
	fft.reset();
	fft.forward = 1;
	fft.forward.timeData$ = ekko00$(i)_A;
	fft.forward.tdelta = 2e-6;
	fft.forward.realData$ = ekko00$(i)_B;
	fft.forward.imagData$ = ekko00$(i)_C
	window -t W fft FFT00$(i)$;
	fft.output.samplingdata$ = FFT00$(i)_Freq;
	fft.output.realdata$ = FFT00$(i)_Real;
	fft.output.imagdata$ = FFT00$(i)_Imag;
	fft.output.ampdata$ = FFT00$(i)_r;
	fft.output.phasedata$ = FFT00$(i)_Phi;
	fft.output.powerdata$ = FFT00$(i)_Power;
	fft.start = 1;
	fft.real = 1;
	fft.normalize = 1;
	fft.shifted = 1;
	fft.windowing = 1;
	fft.spectrum = 1;
	fft.unwrap = 1;
	fft.convention = 1;
	fft.chkres();
	fft.forward();
	window -t P fftplot FFT00$(i)g;
}

Any idea what could be wrong?

Regards,
Espen

[/quote]

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T O P I C R E V I E W
espenhjo	Posted - 02/10/2004 : 06:39:12 AM Hi all! I need to do an FFT on a series of datasets, all having the same structure. For this have I tried to use the LabTalk script in the help file. The thing is that when I use this I don't get the correct FFT as when I select the FFT manually from the analysis menu in Origin. I use exactly the same parameters manually as in this script: loop (i,1,9) { fft.reset(); fft.forward = 1; fft.forward.timeData$ = ekko00$(i)_A; fft.forward.tdelta = 2e-6; fft.forward.realData$ = ekko00$(i)_B; fft.forward.imagData$ = ekko00$(i)_C window -t W fft FFT00$(i)$; fft.output.samplingdata$ = FFT00$(i)_Freq; fft.output.realdata$ = FFT00$(i)_Real; fft.output.imagdata$ = FFT00$(i)_Imag; fft.output.ampdata$ = FFT00$(i)_r; fft.output.phasedata$ = FFT00$(i)_Phi; fft.output.powerdata$ = FFT00$(i)_Power; fft.start = 1; fft.real = 1; fft.normalize = 1; fft.shifted = 1; fft.windowing = 1; fft.spectrum = 1; fft.unwrap = 1; fft.convention = 1; fft.chkres(); fft.forward(); window -t P fftplot FFT00$(i)g; } Any idea what could be wrong? Regards, Espen
1 L A T E S T R E P L I E S (Newest First)
Mike Buess	Posted - 02/10/2004 : 08:14:02 AM Hi Espen, Although the LabTalk FFT object works fine I have always found it to be much more complicated than is necessary for a simple FFT. If you're using Origin 7.0 or later I strongly suggest that you use the OriginC FFT function instead. But the only thing that I see wrong with your script is that fft.real should probably be zero since the input data are complex. Mike Buess Origin WebRing Member Edited by - Mike Buess on 02/10/2004 08:22:38 AM

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