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How to measure pulse/amplitude droop?

I am trying to figure out how to measure pulse/amplitude droop in the labview.
Is there any built in VI that perform this measurement?

Thanks
DB
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Message 1 of 4
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This depends upon exactly what you are trying to measure. Your post is somewhat unclear. It also depends on what LabVIEW version you have. Newer ones contains pulse parameter measurements such as the Timing and Transitions Measurements Express VI. LabVIEW has long had a peak height VI (Peak Detector.vi). There are also a variety of fitting routines, if you need something more custom. Be more specific and we can give you more information. Post some data or an example of what you are trying to do.
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Message 2 of 4
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I am using LV 7.1,and Boonton PPM (peak power meter) to measure pulse droop. There is no built in function that measure pulse droop, so I have to pull waveform out and then measure. I saw Timing and Transitions Measurements Express VI but its not not what I am looking for. I need to measure 10% and 90% into the pulse amplitude. and delta between two is pulse droop. I hope this will help.

THanks
DB
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Message 3 of 4
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Do you want to measure the 10% to 90% height of the pulse itself or the 10% to 90% change in the pulse level? The suspect the latter, or we would not be having this conversation. If you want to do the former, use Amplitude and Levels.vi or Pulse Parameters.vi and scale by 0.8 to get the 10% to 90%. If you want to get the latter, you may be in for more work. First, try to use the overshoot output of Timing and Transition Measurements or Transition Measurements.vi. Read the documentation, as there is a fair amount of flexibility you can put to your advantage. If that doesn't give you good results, use Pulse Measurements.vi to find your pulse, then extract that section of your waveform. Trim the ends to get rid of the rising and falling edges (this should be a constant number of points if your pulses are consistent). Analyze the result for 10% to 90% values. The easiest way to do this is probably to use the array max and min primitive to give you the maximum and minimum points, then scale by 0.8. Alternately, and more robustly, you can duplicate the waveform a couple of times, concatenate the results, and use Amplitude and Levels.vi to find the amplitude. As a final alternative, you could fit the resulting curve to an appropriate line/polynomial/exponential and extract the info from the curve coefficients. This will only work if the data is a well defined curve. Be careful with general polynomial fits.

Good luck. Let us know how you make out.
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Message 4 of 4
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