why does peak detection.vi values doesnot match with array max/min

[freemason]

Hello experts,

I am trying to use peak detection.vi / waveform peak detection.vi on an ECG waveform which has 2 pqrst waveforms, essentialy like 3 peaks each, 1 bigger than other 2 in each.

so peaks are:

1.18434

1.22711

but max value found in the array is only 1.15084, can anybody explain me what is happening, does peak detection just guess/ manipulate to get a peak or is it actually finding values from the array because none of the values are in the array at those locations (indices) or anywhere else in the given array. same is the case for valleys and min of array

its giving little bit more than what i am asking !!

Thanks

[Darin.K]

The peak detector uses a fit to determine the amplitude and location of the peaks.  All that is happening is that the fit is estimating that the true peak was between two of your array points.

[shrekt]

Hi,

Can you provide some code of yours so that we can have alook at it,

Regards,

Shrek

[SanRac]

Hi

If you just want the waveform max and min, then you can use Waveform min max.vi.

hope this helps

Regards,

Santosh

[Coq_Rouge]

Sometimes the peak detection functions find the correct postion but place the peak at wrong amplitude. Try to vary the width parameter. Sometimes I have also used a "tuning" function. This function look at some samples around the the found extremum point and pick the correct value. It do not have to be an equal number of samples. sometimes I have used say 8 samples backward, and 4 samples forward 

[freemason]

Thanks all,

coq Rogue: can you tell me where is a tuning function, i cant find it.

Peak detection is also off by little amount either to left or right in position, and 1st peak/valley amplitudes are more than the array value max/min, 2nd peak and third peak are also little off,

tried varying the width parameter but gives weird results ( i dont fully understand what is width doing) 

can you post an example with tuning?

Thanks,