labview representation of wavefunction

[bufferlab]

Hello All,

I am kind of confuse why the wave representation measured by same oscilloscope is so different. I am not sure whether it is due to oscilloscope or the labview software.

So we collect the data using oscilloscope and it is saved in wave function form. And we use labview to analyze the data. As you can see in the figure attached here, that the yellow peak length in left is so different from the  right. I am wondering why s much change is there. The labview setting used is same for both traces. 

I will appreciate if somebody can help me understand this doubt. 

[crossrulz]

Well, your second plot has a noisy plateau on the way down.  So I would expect your analysis to be different.

[altenbach]

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@bufferlab wrote:

So we collect the data using oscilloscope and it is saved in wave function form. And we use labview to analyze the data.  

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I assume that the white traces are your raw data and the yellow traces are after "analysis", (whatever that means!).

As has been said, your data differs, so hopefully the result will differ too, so be happy about that! 🙂

Of course you haven't mentioned anything about the "analysis" and what the yellow data actually represents. What are the axis names? If you would tell us more and maybe even show us the VI, we can help judge if the analysis algorithm is implemented correctly and suitable for this kind of data.

So far, either your expectations are wrong, the algorithm is wrong, or both. 😮

(...and yes, maybe the oscilloscope is wrong :))

[bufferlab]

Thank you for your reply. 

I have attached a picture of the VI. The white traces is the raw data where the Y axis is conductance and X axis is the length/distance. Here we are trying to measure teh conductance of the molecule. The yellow line is the histogram of that single trace represented above. What I want to understand is that why the histogram peaks are different. All the conditions were kept same. 

PS: We use Yokogawa DL750 oscilloscope which is communicated with labview

Thank you again for your time.

[crossrulz]

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@bufferlab wrote:

I have attached a picture of the VI.

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A picture of the front panel is useless when debugging code.  Just images of the block diagram will likely be useless.  We need the actual VIs if you want us to do any troubleshooting.

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@bufferlab wrote:

What I want to understand is that why the histogram peaks are different. All the conditions were kept same.

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But your data was different.  So something changed as part of the acquisition.  This is likely not a code issue, but a hardware setup issue.

[altenbach]

OK, so these are histograms. Both histograms in the original image look perfect. Part of the confusion might be that the x-axis is different, but that sharp peak at ~2.6 agrees with the near horizontal data between 0 and 0.025. In the data on the left, that same section is more sloping, so it washes out over more bins. What is the bin width? Can you also graph a running integral of the histogram so we can better tell the relative areas? Your bins seem to be smaller than a pixel and details are lost in the display.

How old is this program? LabVIEW 5.0? It seems all the version upgrade and OS changes caused a lot of control overlap and other cosmetic issues.

[bufferlab]

Thank you for your reply. Though it look noisy I think the yellow histogram should show high peaks.

[bufferlab]

It's labview 7.1. As you can see in the image I attached the bin is 0.004.  The “step” setting determines the bin size of the data.

[altenbach]

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@bufferlab wrote:

Thank you for your reply. Though it look noisy I think the yellow histogram should show high peaks.

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All your histograms are yellow. No way to tell what you are talking about here. Data is data.

[bufferlab]

Hello Friends,

I am new to using the instrument in the lab, please pardon my ignorance.

So I was taking data in DL750 oscilloscope communicated with the help of labview software. The ASCII header file shows blocksize as 2002 for the data I am measuring. However, I compared it with the old saved files, the blocksize is 20020. This is the reason when I am trying to analyze the data using labview The histogram of the corresponding trace doesn't have enough data points. Can somebody please explain.

Thank you for your time.