Yoichi Nagashima / Mbed 2 deprecated CQ_nagasm_08_notch_test

add 60Hz/50Hz notch filter

Dependencies:   mbed

notch.hpp@2:048d8bddb100, 2014-12-20 (annotated)

Committer:
nagasm
Date:
Sat Dec 20 02:08:03 2014 +0000
Revision:
2:048d8bddb100
Parent:
1:8fa2f521009a 
revised

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nagasm 0:5ec74240d7f1 1 /*
nagasm 0:5ec74240d7f1 2 #include <stdio.h>
nagasm 0:5ec74240d7f1 3 #include <stdlib.h>
nagasm 0:5ec74240d7f1 4 #include <math.h>
nagasm 0:5ec74240d7f1 5 int main(){
nagasm 0:5ec74240d7f1 6 int fs = 10000;
nagasm 0:5ec74240d7f1 7 double B0, a1, a2, b1, c0, F0, T;
nagasm 0:5ec74240d7f1 8 F0 = 60; // or 50
nagasm 0:5ec74240d7f1 9 B0 = 100.;
nagasm 0:5ec74240d7f1 10 T = 1./fs;
nagasm 0:5ec74240d7f1 11 a1 = 2. * exp(-M_PI * B0 * T) * cos(2. * M_PI * F0 * T);
nagasm 0:5ec74240d7f1 12 a2 = -exp(-2. * M_PI * B0 * T);
nagasm 0:5ec74240d7f1 13 b1 = -2. * cos(2. * M_PI * F0 * T);
nagasm 0:5ec74240d7f1 14 c0 = (1-a1-a2)/(2+b1);
nagasm 0:5ec74240d7f1 15 printf("a1 = %f\n", a1);
nagasm 0:5ec74240d7f1 16 printf("a2 = %f\n", a2);
nagasm 0:5ec74240d7f1 17 printf("b1 = %f\n", b1);
nagasm 0:5ec74240d7f1 18 printf("c0 = %f\n", c0);
nagasm 0:5ec74240d7f1 19 return 0;
nagasm 0:5ec74240d7f1 20 }
nagasm 0:5ec74240d7f1 21 60Hz
nagasm 0:5ec74240d7f1 22 a1 = 1.936768
nagasm 0:5ec74240d7f1 23 a2 = -0.939101
nagasm 0:5ec74240d7f1 24 b1 = -1.998579
nagasm 0:5ec74240d7f1 25 c0 = 1.642174
nagasm 0:5ec74240d7f1 26 50Hz
nagasm 0:5ec74240d7f1 27 a1 = 1.937188
nagasm 0:5ec74240d7f1 28 a2 = -0.939101
nagasm 0:5ec74240d7f1 29 b1 = -1.999013
nagasm 0:5ec74240d7f1 30 c0 = 1.938304
nagasm 0:5ec74240d7f1 31 */
nagasm 0:5ec74240d7f1 32
nagasm 0:5ec74240d7f1 33 const float _60Hz_a1 = 1.936768, _60Hz_a2 = -0.939101, _60Hz_b1 = -1.998579, _60Hz_c0 = 1.642174;
nagasm 0:5ec74240d7f1 34 const float _50Hz_a1 = 1.937188, _50Hz_a2 = -0.939101, _50Hz_b1 = -1.999013, _50Hz_c0 = 1.938304;
nagasm 0:5ec74240d7f1 35 float a1, a2, b1, c0;
nagasm 0:5ec74240d7f1 36 float y1[3], y2[3];
nagasm 1:8fa2f521009a 37 int notch_1, notch_2;
nagasm 0:5ec74240d7f1 38
nagasm 0:5ec74240d7f1 39 void coef_set(int herz){
nagasm 0:5ec74240d7f1 40 if(herz < 55){
nagasm 0:5ec74240d7f1 41 a1 = _50Hz_a1;
nagasm 0:5ec74240d7f1 42 a2 = _50Hz_a2;
nagasm 0:5ec74240d7f1 43 b1 = _50Hz_b1;
nagasm 0:5ec74240d7f1 44 c0 = _50Hz_c0;
nagasm 0:5ec74240d7f1 45 }
nagasm 0:5ec74240d7f1 46 else{
nagasm 0:5ec74240d7f1 47 a1 = _60Hz_a1;
nagasm 0:5ec74240d7f1 48 a2 = _60Hz_a2;
nagasm 0:5ec74240d7f1 49 b1 = _60Hz_b1;
nagasm 0:5ec74240d7f1 50 c0 = _60Hz_c0;
nagasm 0:5ec74240d7f1 51 }
nagasm 0:5ec74240d7f1 52 for (int i=0; i<3; i++) y1[i] = y2[i] = 0;
nagasm 0:5ec74240d7f1 53 }
nagasm 0:5ec74240d7f1 54
nagasm 0:5ec74240d7f1 55 float notch_filter1(float data){
nagasm 0:5ec74240d7f1 56 y1[0] = data + a1*y1[1] + a2*y1[2];
nagasm 0:5ec74240d7f1 57 float reault = y1[0] + b1*y1[1] + y1[2];
nagasm 0:5ec74240d7f1 58 y1[2] = y1[1];
nagasm 0:5ec74240d7f1 59 y1[1] = y1[0];
nagasm 0:5ec74240d7f1 60 return(reault);
nagasm 0:5ec74240d7f1 61 }
nagasm 0:5ec74240d7f1 62
nagasm 0:5ec74240d7f1 63 float notch_filter2(float data){
nagasm 0:5ec74240d7f1 64 y2[0] = data + a1*y2[1] + a2*y2[2];
nagasm 0:5ec74240d7f1 65 float reault = y2[0] + b1*y2[1] + y2[2];
nagasm 0:5ec74240d7f1 66 y2[2] = y2[1];
nagasm 0:5ec74240d7f1 67 y2[1] = y2[0];
nagasm 0:5ec74240d7f1 68 return(reault);
nagasm 0:5ec74240d7f1 69 }