不韋 呂 / UIT_IIR_Filter

縦続形 IIR フィルタ用ライブラリ． Library for cascade structure IIR filter.

Dependents:   Demo_IIR_Filter UIT2_VariableIIR_LPF UIT2_VariableIIR_LPFHPF

Biquad.hpp@0:d2f279439aaf, 2015-09-03 (annotated)

Committer:
MikamiUitOpen
Date:
Thu Sep 03 00:42:10 2015 +0000
Revision:
0:d2f279439aaf
Child:
1:69a8b728e8d2
1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MikamiUitOpen 0:d2f279439aaf 1 //----------------------------------------------------------------
MikamiUitOpen 0:d2f279439aaf 2 // 縦続形 IIR フィルタで使う 1D タイプの 2 次のフィルタ
MikamiUitOpen 0:d2f279439aaf 3 // Biquad filter of 1D type for IIR filter of cascade structure
MikamiUitOpen 0:d2f279439aaf 4 //
MikamiUitOpen 0:d2f279439aaf 5 // u[n] = x[n] + a1*u[n-1] + a2*u[n-2]
MikamiUitOpen 0:d2f279439aaf 6 // y[n] = u[n] + b1*u[n-1] + b2*u[n-2]
MikamiUitOpen 0:d2f279439aaf 7 // x[n] : input signal
MikamiUitOpen 0:d2f279439aaf 8 // y[n] : output signal
MikamiUitOpen 0:d2f279439aaf 9 // b0 = 1
MikamiUitOpen 0:d2f279439aaf 10 //
MikamiUitOpen 0:d2f279439aaf 11 // 2015/09/02, Copyright (c) 2015 MIKAMI, Naoki
MikamiUitOpen 0:d2f279439aaf 12 //----------------------------------------------------------------
MikamiUitOpen 0:d2f279439aaf 13
MikamiUitOpen 0:d2f279439aaf 14 #ifndef IIR_BIQUAD_HPP
MikamiUitOpen 0:d2f279439aaf 15 #define IIR_BIQUAD_HPP
MikamiUitOpen 0:d2f279439aaf 16
MikamiUitOpen 0:d2f279439aaf 17 #include "mbed.h"
MikamiUitOpen 0:d2f279439aaf 18
MikamiUitOpen 0:d2f279439aaf 19 namespace Mikami
MikamiUitOpen 0:d2f279439aaf 20 {
MikamiUitOpen 0:d2f279439aaf 21 class Biquad
MikamiUitOpen 0:d2f279439aaf 22 {
MikamiUitOpen 0:d2f279439aaf 23 public:
MikamiUitOpen 0:d2f279439aaf 24 struct Coefs { float a1, a2, b1, b2; };
MikamiUitOpen 0:d2f279439aaf 25
MikamiUitOpen 0:d2f279439aaf 26 Biquad() {} // default constructor
MikamiUitOpen 0:d2f279439aaf 27
MikamiUitOpen 0:d2f279439aaf 28 Biquad(const Coefs ck)
MikamiUitOpen 0:d2f279439aaf 29 : a1_(ck.a1), a2_(ck.a2), b1_(ck.b1), b2_(ck.b2)
MikamiUitOpen 0:d2f279439aaf 30 { Clear(); }
MikamiUitOpen 0:d2f279439aaf 31
MikamiUitOpen 0:d2f279439aaf 32 float Execute(float xn)
MikamiUitOpen 0:d2f279439aaf 33 {
MikamiUitOpen 0:d2f279439aaf 34 float un = xn + a1_*un1_ + a2_*un2_;
MikamiUitOpen 0:d2f279439aaf 35 float yn = un + b1_*un1_ + b2_*un2_;
MikamiUitOpen 0:d2f279439aaf 36
MikamiUitOpen 0:d2f279439aaf 37 un2_ = un1_;
MikamiUitOpen 0:d2f279439aaf 38 un1_ = un;
MikamiUitOpen 0:d2f279439aaf 39
MikamiUitOpen 0:d2f279439aaf 40 return yn;
MikamiUitOpen 0:d2f279439aaf 41 }
MikamiUitOpen 0:d2f279439aaf 42
MikamiUitOpen 0:d2f279439aaf 43 void Clear() { un1_ = un2_ = 0; }
MikamiUitOpen 0:d2f279439aaf 44
MikamiUitOpen 0:d2f279439aaf 45 private:
MikamiUitOpen 0:d2f279439aaf 46 float a1_, a2_, b1_, b2_; // coefficients
MikamiUitOpen 0:d2f279439aaf 47 float un1_, un2_; // buffer for delay
MikamiUitOpen 0:d2f279439aaf 48
MikamiUitOpen 0:d2f279439aaf 49 // disallow copy constructor and assignment operator
MikamiUitOpen 0:d2f279439aaf 50 Biquad(const Biquad&);
MikamiUitOpen 0:d2f279439aaf 51 Biquad& operator = (const Biquad&);
MikamiUitOpen 0:d2f279439aaf 52 };
MikamiUitOpen 0:d2f279439aaf 53 }
MikamiUitOpen 0:d2f279439aaf 54 #endif // IIR_BIQUAD_HPP
MikamiUitOpen 0:d2f279439aaf 55