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Voltage Stability Measurement from Photodetector (U12/Labview)

Photodetector U12 Labview

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3 replies to this topic

#1 Samuel Goodall

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Posted 24 November 2013 - 09:31 PM

Hello I'm rather new to LabVIEW and LabJack so please forgive me if my problem is a bit basic.


I'm testing the stability of a set of tables in the lab using an interferometer set-up and a photodiode, when the voltage changes this means that tables have been moved. I was thinking of setting up a loop which times how long a particular voltage is stable (loop until change occurs) and sticking that into a table along with measuring the maximum change in voltage throughout the entire run. But looking through your functions I'm not sure which best apply (possibly count for stability duration).

#2 LabJack Support

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Posted 25 November 2013 - 04:32 AM

There are several options here. What are the minimum and maximum times the system may be stable for?

#3 Samuel Goodall

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Posted 26 November 2013 - 08:34 PM

I've been going through my stuff so the method that I'm going through as altered quite a bit.


Basically what the plan is now is to acquire data from the LabJack A0 and A1 ports and runs the voltage vs time through the FFT Power Spectrum to show the if the frequencies of the pulses get either shifted or broadened throughout the sampling. However to be able to view all of the signals I have to run it up to 10 minutes (I can then zoom in on the dominant frequencies). 


I'm not quite sure how to stream data at the rate required (1000 Samples points per Second) for the required 10 minutes. Is it possible or would I have to drop the sample rate? And if it is possible how would I go about it?

#4 LabJack Support

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Posted 27 November 2013 - 09:37 AM

The max rate for 2 channels would be 600 scans/second:




If you need to go faster consider any of our other LabJacks such as the U3, U6, or T7.


Start by just using LJstream.exe to collect 2 channels at 600 scans/second and write to file.  Then if you want to do it yourself in a LabVIEW written program, start with a stream example:



Also tagged with one or more of these keywords: Photodetector, U12, Labview

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