AnalogWaveformGraph PeakDetector

[Tunedport]

Hi,

I am having a problem trying to detect peaks and valleys in an AnalogWaveformGraph.

(I am showing just the parts of the code which I felt was pertinent to the discussion here)

I collect analog current as;

           Private waveformData As AnalogWaveform(Of Double)

This works great for plotting using;

          WaveformGraph1.PlotWaveform(waveformData)

Now I am trying to detect the peaks and valleys using;

        Dim peakPolarity As NationalInstruments.Analysis.Monitoring.PeakPolarity
        Dim peakDetect As NationalInstruments.Analysis.Monitoring.PeakDetector = New NationalInstruments.Analysis.Monitoring.PeakDetector(0, 0, peakPolarity)
 

        peakPolarity = NationalInstruments.Analysis.Monitoring.PeakPolarity.Peaks
        peakDetect.Detect(waveformData, True, amplitudePeak, locationPeak, secondDerivativePeak)

The problem is that the "waveformData" input throws this error;

        Value of type 'NationalInstruments.AnalogWaveform(Of Double)' cannot be converted to '1-dimensional array of Double'

So I'm thinking, the AnalogWaveform data is 2D (T, Value) and the PeakDetector is looking for a 1D array of data?

I tried setting up a sub to convert the waveformData to a standard "double array" I named "waveformArray" so I could extract just the 1 dimension from it;

        Dim waveformArray() As Double = New Double(samplesToReadNumeric - 1) {}
        Dim i As Integer

        For i = 0 To (samplesToReadNumeric - 1)
            waveformArray(i) = waveformData(i, )
        Next i

But I receive and error stating "Class 'NationalInstruments.AnalogWaveform(Of Double)' cannot be indexed because it has no default property."

I looked through all of your examples, including the "PeakDetector" located under "Analysis", but this shows the detector working on a standard double array and I couldn't find any examples with an AnalogWaveform.

I know there is an AnalogWaveformPeakDetector in Labview, but I can't seem to find one in Measurement Studio with VisualBasic 2010, am I missing something?

Thank You,

Bill

[Tunedport]

I figured it out... for anyone else who might have the same issue, the "Samples.Item.Value" is what you need to index, samplesToReadNumeric = the size of the waveFormData collected as AnalogWaveform(Of Double);

Dim waveformArray() As Double = New Double(samplesToReadNumeric - 1) {}

Dim i As Integer

        'Convert waveFormData to waveformArray
        For i = 0 To (samplesToReadNumeric - 1)
            waveformArray(i) = waveformData.Samples.Item(i).Value
        Next i

Then you can run the PeakDetector on your new Array;

        'Detection of Peaks
        peakPolarity = NationalInstruments.Analysis.Monitoring.PeakPolarity.Peaks
        peakDetect.Detect(waveformArray, True, amplitudePeak, locationPeak, secondDerivativePeak)