Imports BasicDSP
Imports ZedGraph
Public Class dsp1ex2
    Public Const FS As Double = 10000
    Public Const LO As Double = 1000
    Public Const HI As Double = 3000

    Private Sub dspex2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim gp As New Graph(Me.CreateGraphics, zgc, 1, 1, "Filter Responses")

        Dim lpfilt As LTISystemChain = Filter.ButterworthLowPass(LO / FS, 4)
        Dim bpfilt As LTISystemChain = Filter.ButterworthBandPass(LO / FS, HI / FS, 4)
        Dim hpfilt As LTISystemChain = Filter.ButterworthHighPass(HI / FS, 4)

        Dim lpresp As New Spectrum(500, FS / 2)
        Dim bpresp As New Spectrum(500, FS / 2)
        Dim hpresp As New Spectrum(500, FS / 2)

        For i As Integer = 0 To 499
            lpresp(i) = lpfilt.Response(i / 1000)
            bpresp(i) = bpfilt.Response(i / 1000)
            hpresp(i) = hpfilt.Response(i / 1000)
        Next

        gp.PlotDbSpectrum(1, lpresp, "Low-pass | Band-pass | High-Pass")
        gp.PlotDbSpectrum(1, bpresp, "Low-pass | Band-pass | High-Pass")
        gp.PlotDbSpectrum(1, hpresp, "Low-pass | Band-pass | High-Pass")

    End Sub
End Class