# LabVIEW

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## fast fourier transform from sampled values of a wave

Hi,

im new to labview .I'm trying to plot frequency spectrum of a FFT. here fft should be constructed using sampled values of a wave stored in spreadsheet. can any one help

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## Re: fast fourier transform from sampled values of a wave

Hi Jane,

fft should be constructed using sampled values of a wave stored in spreadsheet.

Read the spreadsheet data, construct a waveform with this data, then apply a FFT function, plot the result by wiring to a graph. Finished.

can any one help

Well, where are you stuck?

im new to labview

Then I guess you already did the free online courses to learn the basics?

Btw. LabVIEW is written with some uppercase characters… 😄

Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 2 of 7
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## Re: fast fourier transform from sampled values of a wave

@GerdW wrote:

Btw. LabVIEW is written with some uppercase characters… 😄

True.  And also the first letter of the first word of any sentence should be capitalized.

Message 3 of 7
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## Re: fast fourier transform from sampled values of a wave

HI GerdW, Thank you for answering and correcting.As you said I read values from spreadsheet to an array using Read From Spreadsheet File.vi. Now i have to create a signal using these values .Is there any functionality in labVIEW to do this? Signal should have a frequency of 50 Hz. sampling frequency 2 Hz. I want to apply the generated signal to  FFT Power Spectrum.vi . I want to attach my VI and spreadsheet but i dont know how to attach multiple files. Thank you
Message 4 of 7
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## Re: fast fourier transform from sampled values of a wave

Hi janetajaj,

Now i have to create a signal using these values .Is there any functionality in labVIEW to do this?

Signal should have a frequency of 50 Hz. sampling frequency 2 Hz.

This will not work according to work of Nyquist and Shannon…

Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 5 of 7
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## Re: fast fourier transform from sampled values of a wave

Hi

Signal should have a frequency of 50 Hz. sampling frequency 2 Hz.

This will not work according to work of Nyquist and Shannon…

you are right , actually sampling rate is 2 KHz.Is it possible to input sampling frequency?

Message 6 of 7
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## Re: fast fourier transform from sampled values of a wave

Hi janetajaj,

when you would use the BuildWaveform function you would get the option to specify the sampling frequency (aka sampling time dt). And you would NOT get that read coercion dot…

Best regards,
GerdW

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 7 of 7
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