Help with applying Butterworth Filter

busarider29 — Mon, 22 Feb 2016 17:14:52 GMT

I am having difficulties coding a Butterworth filter. I need to acquire the data from an NI analog input, apply the filter and then continuous plot to the Waveform graph. I have looked at the white paper but am still struggling to get the coding correct. Can someone please help? Here is what I have so far. I need to apply the filter before I execute the append but I don't how to apply it. I'm getting errors. I can append the data continuously to the Waveformgraph fine so I know I'm good up to this point.

'Create aquiring task with channels.  Channels configurued in another sub
Dim data() As AnalogWaveform(Of Double)
Dim i As Integer = 0
Dim myTask As New NationalInstruments.DAQmx.Task("myTask1")
reader = New AnalogMultiChannelReader(myTask.Stream)

'Create Filter and set filter parameters
Dim newFilter As New ButterworthLowpassFilter(filterOrder, samplingFrequency, cutoffFrequency)
Dim samplingFrequency As Integer = 1000
Dim filterOrder As Integer = 4
Dim cutoffFrequency As Double = 3.0

'This block of code appends raw data to the WFG, currently no filtering applied
 Try
                data = reader.ReadWaveform(samplingFrequency)
                i = 0
                For Each WaveformGraph In WFGS 'Collection of WaveformGraph objects
                    WaveformGraph.PlotWaveformAppend(data(i))
                    i = i + 1
                Next
Catch
End Try

Re: Help with applying Butterworth Filter

G-IV — Tue, 23 Feb 2016 14:45:30 GMT

Hi busarider29,

We have a shipping example that is installed here: C:\Users\Public\Documents\National Instruments\MStudioVS2013\DotNET\Examples\Analysis\Professional\Filtering\cs

It shows how to use filters.

G-IV

topic Help with applying Butterworth Filter in Measurement Studio for .NET Languages

Help with applying Butterworth Filter

Re: Help with applying Butterworth Filter