filter empty output

[Pj89]

Hi everyone.

I'm new to the forum and quite new to LabView, so excuse me if my question is stupid.

I'm expecting a problem with a VI i did and i can't understand where i do wrong. I'm tring to filter a signal with a bandpass filter. I use the Butterworth Filter block but something goes wrong: the output vector is empty whatever i do.

Can someone figure where's the problem?

I attach a simplified VI with the part of the VI that doesn't works. Even this simplified version doesn't work.

Thank you vey much

[johnsold]

Did you look at the explanation for the error code?  It indicates that the frequencies do not meet the requirement 0 < f_low <= f_high <= fs/2.

It appears that you are specifying the sampling frequency as 1/2000 = 500 microhertz. Is this what you intended?  It certainly violates the inequalities.

Lynn

[Pj89]

Yes, that's correct.

I acquired the data at 2000 Hz. I made the spectrum of it and now i want to "extract" the frequencies between 10 and 20 Hz.

In this VI i've simulated this, but the "original" VI applies this operation to a real civil measurement done at 2KHz where i want to extract the time history of the resonant frequency to measure the dissipation coefficient.

Am I doing it in the wrong way?

PS: i didn't checked the error code because i couldn't find where to find it. Can you please tell me where you found the meaning of that error?

[Pj89]

Sorry. I didn't understood what you were saying. I corrected the VI removing the 1/x block. (It was there since i used the same costant for the "dt" parameter in the waveform build tool)

Now it's true 10 < 20 < 2000 /2.

Moreover (in the "simple version") i switched the hi and the low cutoff freq. 

Thanks for your help, it was a stupid error, but i could solve it.

For future use, where you saw the error explanation? It would have helped me...

[Dennis_Knutson]

Look at your inputs! Besides specifying the wrong fs, your high cutoff frequency is 10 and the low is 20. That is backwards.

[Pj89]

Yes, i saw while you were answering 😉

Thanks really really much for your help, it was a stupid error, but i couldn't solve it.

For future use, where you saw the error explanation? It would have helped me...

[Dennis_Knutson]

Look at your menus. Help>Explain Error. Right below the LabVIEW Help.

[crossrulz]

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@Pj89 wrote:

For future use, where you saw the error explanation? It would have helped me...

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You could also use the Bundle By Name to put the error code into the code and use the Simple Error Handler