peak detector

[Lars Johnson]

I am using 7.1 and trying to use the peak detector vi.  

I am measuring a voltage that decays at different rates so I can't set a high width.  It works fine most of the time, but some of the time it returns multiple peaks over one peak.  Is there any way to check the first derivative is zero?

Thanks

[johnsold]

Derivatives tend to be noisy and finding a zero may be a problem.

Perhaps you could look at the slope over several points. Find an area with a strong positive slope followed a few points later by an area with a strong negative slope. The intersection of the lines represented by the slopes will be close to the peak. However, if your signal has multiple peaks or lots of noise, you will still need to apply your knowledge of the signal and judgement to decide when you have found the peak(s) you want.

Lynn