FFT of recorded waveforms

[Dennis_Knutson]

You have something locally set for a breakpoint if you are still in single step mode.

If you want to subtract one column from another, just wire the arrays up to the subtract function. Since you hijacked this thread, you might want to review the original purpose of the subtraction in the original answer I gave. Your subtraction is done for no reason and the build array at the end is just silly.

[Dennis_Knutson]

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Haroon2k9 wrote:

Thanks for the reply. I am using Tektronix TDS3054C and it is connected to the PC using ethernet (using cross-cable).

cheers

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You can find a driver for that here. Go to the instrument driver network for links on what a driver is and how to use one.In MAX, under the hardware listing, you may have to right click and select to add a TCP/IP resource. Follow the directions.

[Haroon2k9]

Thank you very much for guiding me all the way through. I have found the drivers and was able to capture the waveform using LabView. Thanks for guidance 🙂

Now as I wanted to perform the spectral analysis, I was having some problem.

Could you please have a look at the attached screenshot and guide me further???

Thanks

Haroon

[Dennis_Knutson · Accepted solution]

Instead of the bundle, use a Build Waveform function. Out of the scope function is 'waveform array' and 'X increment'. You only need those. Wire the array to the Y input and x increment to the dt input.

[Haroon2k9]

Thanks for the guidance.

I'll keep on bothering you for your further guidance.

Best regards,

Haroon

[Haroon2k9]

Sorry to bother you again. I have a few more problems now.

1. when I try to log the data using Write to measurement file VI, I am unable to do so. I want to log the data for Amplitude spectrum and phase spectrum. The error message is shown in the screenshots attached as 1.jpg and 2.jpg. Your guidance will be of utmost help to me.

2. When I trigger the waveform again and again, the spectral (FFT) analysis shows that amplitude spectrum remains the same but phase spectrum keeps on changin. What could be the reason for this???

3. Another thing I want to discuss is that, I can use the driver to just capture the waveform. I mean, driver is not sunchronizing with the oscilloscope i.e. I need to run it again manually to get the waveform if any change occurs to the input. How can I synchonize the instrument to the Labview to monitor real time changes to the input???

Thanking in anticipation.

Best regards,

Haroon

[Haroon2k9]

Well, I have almost found out the answer about the question number 2 & 3 which i asked in my last post. However, your guidance regarding the first question i.e. about writing data to the measurement file (excel file) will be really a great help for me.

Best regards,

Haroon

[Dennis_Knutson]

You need to use the Convert to Dynamic Datatype function I believe.

[Haroon2k9]

thank you very much for the reply. But I am afraid, this is not working 😞

any other idea??

Best regards,

Haroon

[Dennis_Knutson]

Looks like the express VI outputs a cluster. If you want to use the Write tp Measurement File, you can probably unbundle that cluster and then wire the outputs to a Build Waveform function where f0=t0 (after conversion to timestamp), df=dt and phase =Y. I would not using the Write to Measurement File so I'm a little unsure of this.