Diff: BilinearDesignLpfHpf/BilinearDesignLH.hpp

Revision:

0:33908268d9ea

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BilinearDesignLpfHpf/BilinearDesignLH.hpp	Fri Sep 11 09:54:45 2015 +0000
@@ -0,0 +1,62 @@
+//------------------------------------------------------------------------------
+//  Design of Butterworth LPF and HPF using bilinear transform -- Header
+//
+//   2014/06/29, Copyright (c) 2014 MIKAMI, Naoki
+//------------------------------------------------------------------------------
+
+#ifndef BILINEAR_BUTTERWORTH_HPP
+#define BILINEAR_BUTTERWORTH_HPP
+
+#include "mbed.h"
+#include <complex>  // requisite
+
+namespace Mikami
+{
+    typedef complex<float> Complex; // define "Complex"
+
+    class BilinearDesign
+    {
+    public:
+        struct Coefs { float a1, a2, b1; };
+        enum Type { LPF, HPF };
+
+        // Constructor
+        BilinearDesign(int order, float fs, Type pb)
+            : PI_FS_(PI_/fs), ORDER_(order), PB_(pb)
+        {
+            sP_ = new Complex[order/2];
+            zP_ = new Complex[order/2];
+            ck_ = new Coefs[order/2];
+        }
+
+        // Destractor
+        ~BilinearDesign()
+        {
+            delete[] sP_;
+            delete[] zP_;
+            delete[] ck_;
+        }
+
+        // Execution of design
+        void Execute(float fc, Coefs c[], float& g);
+
+    private:
+        static const float PI_ = 3.1415926536f;
+        const float PI_FS_;
+        const int ORDER_;
+        const Type PB_;
+
+        Complex* sP_;   // Poles on s-plane
+        Complex* zP_;   // Poles on z-plane
+        Coefs* ck_;     // Coefficients of transfer function for cascade form
+        float gain_;    // Gain factor for cascade form
+
+        void Butterworth();
+        void Bilinear(float fc);
+        void ToCascade();
+        void GetGain();
+        void GetCoefs(Coefs c[], float& gain);
+    };
+}
+#endif  // BILINEAR_BUTTERWORTH_HPP
+