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Biquad.hpp@0:cacfc9e25452, 2019-06-04 (annotated)
- Committer:
- phungductung
- Date:
- Tue Jun 04 21:58:08 2019 +0000
- Revision:
- 0:cacfc9e25452
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Who changed what in which revision?
User | Revision | Line number | New contents of line |
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phungductung | 0:cacfc9e25452 | 1 | //-------------------------------------------------------------- |
phungductung | 0:cacfc9e25452 | 2 | // 縦続形 IIR フィルタで使う 1D タイプの 2 次のフィルタ |
phungductung | 0:cacfc9e25452 | 3 | // Biquad filter of 1D type for IIR filter of cascade structure |
phungductung | 0:cacfc9e25452 | 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 |
phungductung | 0:cacfc9e25452 | 5 | // |
phungductung | 0:cacfc9e25452 | 6 | // u[n] = x[n] + a1*u[n-1] + a2*u[n-2] |
phungductung | 0:cacfc9e25452 | 7 | // y[n] = u[n] + b1*u[n-1] + b2*u[n-2] |
phungductung | 0:cacfc9e25452 | 8 | // x[n] : input signal |
phungductung | 0:cacfc9e25452 | 9 | // y[n] : output signal |
phungductung | 0:cacfc9e25452 | 10 | // b0 = 1 |
phungductung | 0:cacfc9e25452 | 11 | // |
phungductung | 0:cacfc9e25452 | 12 | // 2016/03/25, Copyright (c) 2016 MIKAMI, Naoki |
phungductung | 0:cacfc9e25452 | 13 | //-------------------------------------------------------------- |
phungductung | 0:cacfc9e25452 | 14 | |
phungductung | 0:cacfc9e25452 | 15 | #ifndef IIR_BIQUAD_HPP |
phungductung | 0:cacfc9e25452 | 16 | #define IIR_BIQUAD_HPP |
phungductung | 0:cacfc9e25452 | 17 | |
phungductung | 0:cacfc9e25452 | 18 | #include "mbed.h" |
phungductung | 0:cacfc9e25452 | 19 | |
phungductung | 0:cacfc9e25452 | 20 | // 2nd order IIR filter |
phungductung | 0:cacfc9e25452 | 21 | namespace Mikami |
phungductung | 0:cacfc9e25452 | 22 | { |
phungductung | 0:cacfc9e25452 | 23 | class Biquad |
phungductung | 0:cacfc9e25452 | 24 | { |
phungductung | 0:cacfc9e25452 | 25 | public: |
phungductung | 0:cacfc9e25452 | 26 | struct Coefs { float a1, a2, b1, b2; }; |
phungductung | 0:cacfc9e25452 | 27 | |
phungductung | 0:cacfc9e25452 | 28 | Biquad() {} // Default constructore |
phungductung | 0:cacfc9e25452 | 29 | |
phungductung | 0:cacfc9e25452 | 30 | Biquad(const Coefs ck) |
phungductung | 0:cacfc9e25452 | 31 | { |
phungductung | 0:cacfc9e25452 | 32 | SetCoefficients(ck); |
phungductung | 0:cacfc9e25452 | 33 | Clear(); |
phungductung | 0:cacfc9e25452 | 34 | } |
phungductung | 0:cacfc9e25452 | 35 | |
phungductung | 0:cacfc9e25452 | 36 | void SetCoefficients(const Coefs ck) |
phungductung | 0:cacfc9e25452 | 37 | { |
phungductung | 0:cacfc9e25452 | 38 | a1_ = ck.a1; |
phungductung | 0:cacfc9e25452 | 39 | a2_ = ck.a2; |
phungductung | 0:cacfc9e25452 | 40 | b1_ = ck.b1; |
phungductung | 0:cacfc9e25452 | 41 | b2_ = ck.b2; |
phungductung | 0:cacfc9e25452 | 42 | } |
phungductung | 0:cacfc9e25452 | 43 | |
phungductung | 0:cacfc9e25452 | 44 | float Execute(float xn) |
phungductung | 0:cacfc9e25452 | 45 | { |
phungductung | 0:cacfc9e25452 | 46 | float un = xn + a1_*un1_ + a2_*un2_; |
phungductung | 0:cacfc9e25452 | 47 | float yn = un + b1_*un1_ + b2_*un2_; |
phungductung | 0:cacfc9e25452 | 48 | |
phungductung | 0:cacfc9e25452 | 49 | un2_ = un1_; |
phungductung | 0:cacfc9e25452 | 50 | un1_ = un; |
phungductung | 0:cacfc9e25452 | 51 | |
phungductung | 0:cacfc9e25452 | 52 | return yn; |
phungductung | 0:cacfc9e25452 | 53 | } |
phungductung | 0:cacfc9e25452 | 54 | |
phungductung | 0:cacfc9e25452 | 55 | void Clear() { un1_ = un2_ = 0; } |
phungductung | 0:cacfc9e25452 | 56 | |
phungductung | 0:cacfc9e25452 | 57 | private: |
phungductung | 0:cacfc9e25452 | 58 | float a1_, a2_, b1_, b2_; |
phungductung | 0:cacfc9e25452 | 59 | float un1_, un2_; |
phungductung | 0:cacfc9e25452 | 60 | |
phungductung | 0:cacfc9e25452 | 61 | // disallow copy constructor |
phungductung | 0:cacfc9e25452 | 62 | Biquad(const Biquad&); |
phungductung | 0:cacfc9e25452 | 63 | }; |
phungductung | 0:cacfc9e25452 | 64 | } |
phungductung | 0:cacfc9e25452 | 65 | #endif // IIR_BIQUAD_HPP |