Data Acquisition Above Threshold

[Ivan899]

Hello,

I started with LabVIEW a few days ago and find it quite difficult. Hope that you can help me a bit.

My task is: 2 channels (from acoustic sensors), I need to find time delay of arrival between them and then compute the coordinates of a source that emits acoustic waves. So, I considered multiple examples that I managed to find and I am finally stuck at the very beginning. 

I need to work with signals (impulses) that are higher than a specific threshold, but how can I do that? Do I need to use Threshold Detector.vi or not? 

Then I need to find time delay of arrival. Should I use CrossCorrelation.vi? 

Thanks a lot.

[mikeporter]

What do the data waveforms actually look like?

Mike...

[Ivan899]

Something like this. So it means that the system should ignore noise and start to acquire signal when its amplitude reaches a specific threshold.

[mikeporter]

I think I would use the threshold function in LV to find the initial high peak in each waveform. That will return the x-index of the point. That information and the sample clock frequency will allow you to calculate delta times.

Alternately, you could use a simple comparison. The output would be an array of booleans, find the first one that is true and that index would be used in your time calculations.

Mike...

[Ivan899]

In what point of the provided circuit do you think I should connect threshold detector.vi? I am asking this because it is confusing for me: elements in the circuit and threshold detector work with different type of wires.. 

[mikeporter · Accepted solution]

Ok, the waveform datatype coming from the read in your original image is just the default output. You can also acquire all three channels in a single acquisition task by specifying multiple physical channels and change the output format to a 2D DBL array. In that form, the columns are the different channels in your acq task. You can then process each channel as I described.

Mike...

[Ivan899]

Thank you so much!