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
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Who changed what in which revision?
User | Revision | Line number | New contents of line |
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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 |