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Cutoff frequency variable LPF and HPF by IIR 6th-order Butterworth filter for ST Nucleo F401RE.
Dependencies: UITDSP_ADDA UIT_ACM1602NI UIT_AQM1602 UIT_IIR_Filter mbed
BilinearDesignLpfHpf/BilinearDesignLH.hpp@0:33908268d9ea, 2015-09-11 (annotated)
- Committer:
- MikamiUitOpen
- Date:
- Fri Sep 11 09:54:45 2015 +0000
- Revision:
- 0:33908268d9ea
1
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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MikamiUitOpen | 0:33908268d9ea | 1 | //------------------------------------------------------------------------------ |
MikamiUitOpen | 0:33908268d9ea | 2 | // Design of Butterworth LPF and HPF using bilinear transform -- Header |
MikamiUitOpen | 0:33908268d9ea | 3 | // |
MikamiUitOpen | 0:33908268d9ea | 4 | // 2014/06/29, Copyright (c) 2014 MIKAMI, Naoki |
MikamiUitOpen | 0:33908268d9ea | 5 | //------------------------------------------------------------------------------ |
MikamiUitOpen | 0:33908268d9ea | 6 | |
MikamiUitOpen | 0:33908268d9ea | 7 | #ifndef BILINEAR_BUTTERWORTH_HPP |
MikamiUitOpen | 0:33908268d9ea | 8 | #define BILINEAR_BUTTERWORTH_HPP |
MikamiUitOpen | 0:33908268d9ea | 9 | |
MikamiUitOpen | 0:33908268d9ea | 10 | #include "mbed.h" |
MikamiUitOpen | 0:33908268d9ea | 11 | #include <complex> // requisite |
MikamiUitOpen | 0:33908268d9ea | 12 | |
MikamiUitOpen | 0:33908268d9ea | 13 | namespace Mikami |
MikamiUitOpen | 0:33908268d9ea | 14 | { |
MikamiUitOpen | 0:33908268d9ea | 15 | typedef complex<float> Complex; // define "Complex" |
MikamiUitOpen | 0:33908268d9ea | 16 | |
MikamiUitOpen | 0:33908268d9ea | 17 | class BilinearDesign |
MikamiUitOpen | 0:33908268d9ea | 18 | { |
MikamiUitOpen | 0:33908268d9ea | 19 | public: |
MikamiUitOpen | 0:33908268d9ea | 20 | struct Coefs { float a1, a2, b1; }; |
MikamiUitOpen | 0:33908268d9ea | 21 | enum Type { LPF, HPF }; |
MikamiUitOpen | 0:33908268d9ea | 22 | |
MikamiUitOpen | 0:33908268d9ea | 23 | // Constructor |
MikamiUitOpen | 0:33908268d9ea | 24 | BilinearDesign(int order, float fs, Type pb) |
MikamiUitOpen | 0:33908268d9ea | 25 | : PI_FS_(PI_/fs), ORDER_(order), PB_(pb) |
MikamiUitOpen | 0:33908268d9ea | 26 | { |
MikamiUitOpen | 0:33908268d9ea | 27 | sP_ = new Complex[order/2]; |
MikamiUitOpen | 0:33908268d9ea | 28 | zP_ = new Complex[order/2]; |
MikamiUitOpen | 0:33908268d9ea | 29 | ck_ = new Coefs[order/2]; |
MikamiUitOpen | 0:33908268d9ea | 30 | } |
MikamiUitOpen | 0:33908268d9ea | 31 | |
MikamiUitOpen | 0:33908268d9ea | 32 | // Destractor |
MikamiUitOpen | 0:33908268d9ea | 33 | ~BilinearDesign() |
MikamiUitOpen | 0:33908268d9ea | 34 | { |
MikamiUitOpen | 0:33908268d9ea | 35 | delete[] sP_; |
MikamiUitOpen | 0:33908268d9ea | 36 | delete[] zP_; |
MikamiUitOpen | 0:33908268d9ea | 37 | delete[] ck_; |
MikamiUitOpen | 0:33908268d9ea | 38 | } |
MikamiUitOpen | 0:33908268d9ea | 39 | |
MikamiUitOpen | 0:33908268d9ea | 40 | // Execution of design |
MikamiUitOpen | 0:33908268d9ea | 41 | void Execute(float fc, Coefs c[], float& g); |
MikamiUitOpen | 0:33908268d9ea | 42 | |
MikamiUitOpen | 0:33908268d9ea | 43 | private: |
MikamiUitOpen | 0:33908268d9ea | 44 | static const float PI_ = 3.1415926536f; |
MikamiUitOpen | 0:33908268d9ea | 45 | const float PI_FS_; |
MikamiUitOpen | 0:33908268d9ea | 46 | const int ORDER_; |
MikamiUitOpen | 0:33908268d9ea | 47 | const Type PB_; |
MikamiUitOpen | 0:33908268d9ea | 48 | |
MikamiUitOpen | 0:33908268d9ea | 49 | Complex* sP_; // Poles on s-plane |
MikamiUitOpen | 0:33908268d9ea | 50 | Complex* zP_; // Poles on z-plane |
MikamiUitOpen | 0:33908268d9ea | 51 | Coefs* ck_; // Coefficients of transfer function for cascade form |
MikamiUitOpen | 0:33908268d9ea | 52 | float gain_; // Gain factor for cascade form |
MikamiUitOpen | 0:33908268d9ea | 53 | |
MikamiUitOpen | 0:33908268d9ea | 54 | void Butterworth(); |
MikamiUitOpen | 0:33908268d9ea | 55 | void Bilinear(float fc); |
MikamiUitOpen | 0:33908268d9ea | 56 | void ToCascade(); |
MikamiUitOpen | 0:33908268d9ea | 57 | void GetGain(); |
MikamiUitOpen | 0:33908268d9ea | 58 | void GetCoefs(Coefs c[], float& gain); |
MikamiUitOpen | 0:33908268d9ea | 59 | }; |
MikamiUitOpen | 0:33908268d9ea | 60 | } |
MikamiUitOpen | 0:33908268d9ea | 61 | #endif // BILINEAR_BUTTERWORTH_HPP |
MikamiUitOpen | 0:33908268d9ea | 62 |