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@2:2533ed0150e7, 2015-09-11 (annotated)
- Committer:
- MikamiUitOpen
- Date:
- Fri Sep 11 08:50:13 2015 +0000
- Revision:
- 2:2533ed0150e7
- Parent:
- 1:69a8b728e8d2
3
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 | 1:69a8b728e8d2 | 4 | // このクラスでは,係数は実行中に書き換えられることを想定している |
MikamiUitOpen | 0:d2f279439aaf | 5 | // |
MikamiUitOpen | 0:d2f279439aaf | 6 | // u[n] = x[n] + a1*u[n-1] + a2*u[n-2] |
MikamiUitOpen | 0:d2f279439aaf | 7 | // y[n] = u[n] + b1*u[n-1] + b2*u[n-2] |
MikamiUitOpen | 0:d2f279439aaf | 8 | // x[n] : input signal |
MikamiUitOpen | 0:d2f279439aaf | 9 | // y[n] : output signal |
MikamiUitOpen | 0:d2f279439aaf | 10 | // b0 = 1 |
MikamiUitOpen | 0:d2f279439aaf | 11 | // |
MikamiUitOpen | 1:69a8b728e8d2 | 12 | // 2015/09/11, Copyright (c) 2015 MIKAMI, Naoki |
MikamiUitOpen | 0:d2f279439aaf | 13 | //---------------------------------------------------------------- |
MikamiUitOpen | 0:d2f279439aaf | 14 | |
MikamiUitOpen | 0:d2f279439aaf | 15 | #ifndef IIR_BIQUAD_HPP |
MikamiUitOpen | 0:d2f279439aaf | 16 | #define IIR_BIQUAD_HPP |
MikamiUitOpen | 0:d2f279439aaf | 17 | |
MikamiUitOpen | 0:d2f279439aaf | 18 | #include "mbed.h" |
MikamiUitOpen | 0:d2f279439aaf | 19 | |
MikamiUitOpen | 0:d2f279439aaf | 20 | namespace Mikami |
MikamiUitOpen | 0:d2f279439aaf | 21 | { |
MikamiUitOpen | 1:69a8b728e8d2 | 22 | // 2nd order IIR filter |
MikamiUitOpen | 0:d2f279439aaf | 23 | class Biquad |
MikamiUitOpen | 0:d2f279439aaf | 24 | { |
MikamiUitOpen | 0:d2f279439aaf | 25 | public: |
MikamiUitOpen | 0:d2f279439aaf | 26 | struct Coefs { float a1, a2, b1, b2; }; |
MikamiUitOpen | 0:d2f279439aaf | 27 | |
MikamiUitOpen | 1:69a8b728e8d2 | 28 | Biquad() {} // Default constructore |
MikamiUitOpen | 1:69a8b728e8d2 | 29 | |
MikamiUitOpen | 0:d2f279439aaf | 30 | Biquad(const Coefs ck) |
MikamiUitOpen | 1:69a8b728e8d2 | 31 | { |
MikamiUitOpen | 1:69a8b728e8d2 | 32 | SetCoefs(ck); |
MikamiUitOpen | 1:69a8b728e8d2 | 33 | Clear(); |
MikamiUitOpen | 1:69a8b728e8d2 | 34 | } |
MikamiUitOpen | 1:69a8b728e8d2 | 35 | |
MikamiUitOpen | 1:69a8b728e8d2 | 36 | void SetCoefs(const Coefs ck) |
MikamiUitOpen | 1:69a8b728e8d2 | 37 | { |
MikamiUitOpen | 1:69a8b728e8d2 | 38 | a1_ = ck.a1; |
MikamiUitOpen | 1:69a8b728e8d2 | 39 | a2_ = ck.a2; |
MikamiUitOpen | 1:69a8b728e8d2 | 40 | b1_ = ck.b1; |
MikamiUitOpen | 1:69a8b728e8d2 | 41 | b2_ = ck.b2; |
MikamiUitOpen | 1:69a8b728e8d2 | 42 | } |
MikamiUitOpen | 0:d2f279439aaf | 43 | |
MikamiUitOpen | 0:d2f279439aaf | 44 | float Execute(float xn) |
MikamiUitOpen | 0:d2f279439aaf | 45 | { |
MikamiUitOpen | 0:d2f279439aaf | 46 | float un = xn + a1_*un1_ + a2_*un2_; |
MikamiUitOpen | 0:d2f279439aaf | 47 | float yn = un + b1_*un1_ + b2_*un2_; |
MikamiUitOpen | 1:69a8b728e8d2 | 48 | |
MikamiUitOpen | 0:d2f279439aaf | 49 | un2_ = un1_; |
MikamiUitOpen | 0:d2f279439aaf | 50 | un1_ = un; |
MikamiUitOpen | 1:69a8b728e8d2 | 51 | |
MikamiUitOpen | 0:d2f279439aaf | 52 | return yn; |
MikamiUitOpen | 0:d2f279439aaf | 53 | } |
MikamiUitOpen | 1:69a8b728e8d2 | 54 | |
MikamiUitOpen | 0:d2f279439aaf | 55 | void Clear() { un1_ = un2_ = 0; } |
MikamiUitOpen | 1:69a8b728e8d2 | 56 | |
MikamiUitOpen | 0:d2f279439aaf | 57 | private: |
MikamiUitOpen | 1:69a8b728e8d2 | 58 | float a1_, a2_, b1_, b2_; |
MikamiUitOpen | 1:69a8b728e8d2 | 59 | float un1_, un2_; |
MikamiUitOpen | 0:d2f279439aaf | 60 | |
MikamiUitOpen | 0:d2f279439aaf | 61 | // disallow copy constructor and assignment operator |
MikamiUitOpen | 0:d2f279439aaf | 62 | Biquad(const Biquad&); |
MikamiUitOpen | 0:d2f279439aaf | 63 | Biquad& operator = (const Biquad&); |
MikamiUitOpen | 0:d2f279439aaf | 64 | }; |
MikamiUitOpen | 0:d2f279439aaf | 65 | } |
MikamiUitOpen | 0:d2f279439aaf | 66 | #endif // IIR_BIQUAD_HPP |
MikamiUitOpen | 0:d2f279439aaf | 67 |