====code====
Function HILBERT(ByRef X() As Single, ByVal TS As Double, ByVal WMIN As Double, ByVal WMAX As Double) As Single()
            Try
                Dim DEN() As Complex = {Nothing, COMPLEXUNITY()}
                Dim NUM(), Z() As Complex
                Dim WP(2) As Double
                Dim Y() As Single
                Dim I, N As Integer
                WP(1) = WMIN   ' Нижняя частота среза 
                WP(2) = WMAX   ' Верхняя частота среза 
                ' Нормировать к частоте Найквиста
                For I = 1 To 2
                    WP(I) = WP(I) * TS ' Конец полосы пропускания
                    Select Case WP(I)
                        Case Is <= 0
                            WP(I) = 0.01
                        Case Is > 0.499
                            WP(I) = 0.499
                    End Select
                Next I
                ' Синтез нерекурсивного полосового фильтра с использованием весовых окон
                NUM = Fir1(30, WP, Filtertype.BandPass)
                ' Фильтровать исходные данные
                Y = filtfilt(NUM, DEN, X)
                ' Вычислить преобразование Гильберта
                Z = Hilbert2(Y)
                ' Сформировать огибающую сигнала
                N = Z.GetUpperBound(0)
                ReDim Y(N)
                For I = 1 To N
                    Y(I) = CSng(Rho(Z(I)))
                Next I
                Return Y
            Catch E As Exception
                Throw New ArgumentException(E.Message)
            End Try
        End Function
        Function Hilbert2(ByVal X() As Single) As Complex()
            Try
                Dim J, K, M, N, NFFT As Integer
                N = X.GetUpperBound(0)
                Dim XSEG() As Complex = fft(X)
                NFFT = XSEG.GetUpperBound(0)
                Dim H(NFFT) As Integer
                K = CInt(2 * Fix(N * 0.5))
                If K = N Then
                    M = CInt(N * 0.5)
                    H(1) = 1
                    H(M + 1) = 1
                Else
                    M = CInt((N + 1) * 0.5)
                    H(1) = 1
                End If
                For J = 2 To M
                    H(J) = 2
                Next J
                For J = 1 To NFFT
                    XSEG(J) *= H(J)
                Next J
                XSEG = fft(XSEG, IFFT:=True)
                ReDim Preserve XSEG(N)
                Return XSEG
            Catch E As Exception
                Throw New ArgumentException(E.Message)
            End Try
        End Function
=============