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How to sample a waveform at timed intervals

I am trying to test an infra red detector by pulsing a source and measuring the response. I want to sample the detected signal at its highest and lowest point at timed intervals so that I am only looking at the signal once it has plateaued out. I then want to average the high and the low readings and judge the signal to noise ratio of the detector. I only have a small amount of experience with labview and am not sure what is the best way to approach this. I have included a picture of a typical signal I want to measure.

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Hello psheldrick,

 

I am an Applications Engineer here at National Instruments UK, I should be able to point you in the right direction I just need a little more information from yourself.

 

1 - What version of LabVIEW are you using?

2 - How are you acquiring the signal from the infra red detector into your PC, ie name of the DAQ card?

3- And finally would it be possible to get an overview of the project you are working on?

 

If you reply to this post I will see what I can do to assist you.

 

Kind Regards

Dan Vickers - Applications Engineer UK and Ireland
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Hi Dan,

 

Thanks for the reply. I work for company called Codel International that makes gas analyzers which measure various gases using infra-red. Our systems use Peltier cooled detectors that need to have a low signal to noise ratio and I am trying to build a test rig to pre-test the detector and the pre-amp before it is built into the final product. I am planning to pulse an infra-red source at the detector to simulate the signal it would normally see but am only wanting to sample the signal level in the on and off state as the signal levels off not during the rise and fall time. I am using Labview 2010 and currently have a NI USB-6211 but am aware I might need something different. I want to use a simple square wave to pulse the source and sample at certain points of the duty cycle. Any advice or help would be appreciated on both how to do this and any hardware I might require.

 

Thanks,

 

Phil Sheldrick

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