Peak detection (threshold detector) from spreadsheets.

Hello!
I am working on VI that reads two signals, detects peaks that are above a specific treshold and then estimates time difference between these peaks in samples and in seconds.
Recently I have obtained two waveforms using an oscilloscope in a laboratory. Then I saved these two graphs in a spreadsheet in Excel format (first number is time, second is amplitude). Time difference between them is really small, just a few nanoseconds according to the oscilloscope. I think treshold should be 0.3.
My question is how to make Threshold Detector.vi read values from two excel files? Or maybe I need to use another instrument for this purpose. I am quite confused.
I attached all materials I have.
Any help is highly appreciated!
Thank you.
Attachments:
Inception 2.vi ‏55 KB
position S1-S2a.jpg ‏3004 KB

I tried Read From Spreadsheet File.vi, but have not got any positive result. Probably it reads my spreadsheets, but peak detection does not work properly. When I set up any threshold in Threshold Detector.vi that is more than zero (for example, 0.01), final results turn to zero. The same occurs when indexes in Index Array are not zeroes.
I attached my vi saved for LV2009. Please, have a look.
Thanks.
Attachments:
Inception 2.vi ‏49 KB
Peak detection.jpg ‏108 KB

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Peak detection with two thresholds

Dear colleagues!
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If I understand correctly, you want to set two thresholds as shown in the image below.
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Chris,
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Have you read the LabVIEW Help file (when looking at the BD, type Ctrl-H, then go to the "Detailed help" at the bottom of the popup) about the peak detection function?
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Problem in peak detection

Respected sir/madam,
i am actually processing human radial artery pulse signal... i acquired that signal and linearised that by using filter...
there is a problem in peak amplitude detection and location...by manually we can say there is more number of peaks ..but peak detector shows only 25 peak's amplitude and their locations...i can't understand about locations that shows..i attached the data which is in .lvm extension and the vi
please help me to rectify the problem..
thank you
Attachments:
Untitled 2.vi ‏100 KB
Untitled 2.vi ‏100 KB

Once again the Dynamic Data Type (DDT) generated by the Express VIs hides the real problem.
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There is a lot of "stuff" in this VI - things I tried and did not remove and multiple ways of doing things. The enabled diagrm of the Diagram Disable structure has a constant with the data from your file so that I did not need to read and process the file repeatedly while working on the filters and peak detector.
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1. The DDT data from Read from Measurement File.vi is converted to an array of waveforms. The Waveform data type is well docmuented and the internal data structure is readliy accessible.
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The .2 VI contains all the junk code I described above. The .3 VI is a cleaned up version.
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Untitled 2-9.2.vi ‏760 KB
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Threshold detector vi?

Is there a vi that detects threshold as aposed to peak. My application has two wavelets produced by echo's from the interior of a gun barrel. These waves change in amplitude therefore the peak detection doesn't work becase the threshold setting must be variable. I belive that a threshold detector vi would do the trick.
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http://www.nr.com/
http://en.wikipedia.org/wiki/Numerical_Recipes
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Greetings from Germany
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“ground” is a convenient fantasy
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Peak Detection with Base package

Hello,
I'm constrained by a budget so I can't purchase the analysis package
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Labviewguru wrote in message news:<[email protected]>...
> Jason,
>
> I would suggest looking online for a "peak detection" algorithm.
> There are a number of ways to do it. The LabVIEW peak detector using
> a least squares quadratic fit to find the peaks, with a filter of
> amplitude and width. This can also be done much simpler ways. You
> can try applying a smoothing filter (use a moving or windowed average)
> and then look for peaks that way.
>
> Please post if you need more assistance. Also, what are you trying to
> do with the peak detection. This would be helpful in providing
> further assistance.
>
> Good luck
Labviewguru
Thanks for the advice. Yeah, the NI home page tells me that th
ey use a
least square quadratic fit to find the peaks. I'm not sure on how to
implement that. I'll do a web search on that one. I'm not dealing with
a very noisy signal so I don't think that I need to do a moving
average. The amplitude filter seems pretty easy, I just compare each
point to a preset threshold. However my peaks are composed of more
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Hi,
Had a look at ur VI
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For example, here it detected a significant drop in light intensity 6 times over a 6 second period, so BPM should be 60, but it doesn't display anything.
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Peak detection (threshold detector) from spreadsheets.

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