不韋 呂
Demo program of digital signal processing: Variable LPF/HPF, Vocal canceller, Pitch shifter, Reverbrator. ディジタル信号処理のデモプログラム． 遮断周波数可変 LPF/HPF，ボーカルキャンセラ，ピッチシフタ，残響生成器．
Dependencies: Array_Matrix F446_AD_DA UIT_AQM1602 mbed
Diff: SignalProcessing/BilinearDesignLH.hpp
- Revision:
- 0:fa74b1130cc3
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/SignalProcessing/BilinearDesignLH.hpp Sun Jan 29 09:11:30 2017 +0000
@@ -0,0 +1,53 @@
+//------------------------------------------------------------------------
+// Design of Butterworth LPF and HPF using bilinear transform -- Header
+//
+// 2016/03/31, Copyright (c) 2016 MIKAMI, Naoki
+//------------------------------------------------------------------------
+
+#ifndef BILINEAR_BUTTERWORTH_HPP
+#define BILINEAR_BUTTERWORTH_HPP
+
+#include "mbed.h"
+#include <complex> // requisite
+#include "Array.hpp"
+
+namespace Mikami
+{
+ typedef complex<float> Complex; // define "Complex"
+
+ class BilinearDesign
+ {
+ public:
+ struct Coefs { float a1, a2, b1, b2; };
+ enum Type { LPF, HPF };
+
+ // Constructor
+ BilinearDesign(int order, float fs)
+ : PI_FS_(PI_/fs), ORDER_(order),
+ sP_(order/2), zP_(order/2), ck_(order/2) {}
+
+ // Destractor
+ virtual ~BilinearDesign() {}
+
+ // Execution of design
+ void Execute(float fc, Type pb, Coefs c[], float& g);
+
+ private:
+ static const float PI_ = 3.1415926536f;
+ const float PI_FS_;
+ const int ORDER_;
+
+ Array<Complex> sP_; // Poles on s-plane
+ Array<Complex> zP_; // Poles on z-plane
+ Array<Coefs> ck_; // Coefficients of transfer function for cascade form
+
+ float gain_; // Gain factor for cascade form
+
+ void Butterworth();
+ void Bilinear(float fc);
+ void ToCascade(Type pb);
+ void GetGain(Type pb);
+ void GetCoefs(Coefs c[], float& gain);
+ };
+}
+#endif // BILINEAR_BUTTERWORTH_HPP