How to measure pulse/amplitude droop?

Question

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

Answer 1

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.
This account is no longer active. Contact ShadesOfGray for current posts and information.