Steven Swenson / FrequencyFinder

Class to determine the frequency of an input array

Dependents:   tuner

FrequencyFinder.cpp@0:78c2ee8ea962, 2012-11-25 (annotated)

Committer:
melangeaddict
Date:
Sun Nov 25 23:10:33 2012 +0000
Revision:
0:78c2ee8ea962
[mbed] converted /tuner/FrequencyFinder

Who changed what in which revision?

UserRevisionLine numberNew contents of line
melangeaddict 0:78c2ee8ea962 1 #include "FrequencyFinder.h"
melangeaddict 0:78c2ee8ea962 2
melangeaddict 0:78c2ee8ea962 3 using namespace std;
melangeaddict 0:78c2ee8ea962 4
melangeaddict 0:78c2ee8ea962 5 FrequencyFinder::FrequencyFinder(PinName input) : _signal_in(input), _dc_offset(p18) {
melangeaddict 0:78c2ee8ea962 6 index=0;
melangeaddict 0:78c2ee8ea962 7 peak=0;
melangeaddict 0:78c2ee8ea962 8 frequency_final=0;
melangeaddict 0:78c2ee8ea962 9 }
melangeaddict 0:78c2ee8ea962 10
melangeaddict 0:78c2ee8ea962 11 FrequencyFinder::~FrequencyFinder() {
melangeaddict 0:78c2ee8ea962 12 ticker.detach();
melangeaddict 0:78c2ee8ea962 13 }
melangeaddict 0:78c2ee8ea962 14
melangeaddict 0:78c2ee8ea962 15 float FrequencyFinder::find_frequency() {
melangeaddict 0:78c2ee8ea962 16 initialize_array();
melangeaddict 0:78c2ee8ea962 17 ticker.attach_us(this, &FrequencyFinder::get_data,500);
melangeaddict 0:78c2ee8ea962 18
melangeaddict 0:78c2ee8ea962 19 wait(1);
melangeaddict 0:78c2ee8ea962 20 ticker.detach();
melangeaddict 0:78c2ee8ea962 21
melangeaddict 0:78c2ee8ea962 22 copy_data();
melangeaddict 0:78c2ee8ea962 23
melangeaddict 0:78c2ee8ea962 24 vRealFFT(signal_array,size);
melangeaddict 0:78c2ee8ea962 25
melangeaddict 0:78c2ee8ea962 26 take_abs();
melangeaddict 0:78c2ee8ea962 27
melangeaddict 0:78c2ee8ea962 28 int peak = find_peak();
melangeaddict 0:78c2ee8ea962 29
melangeaddict 0:78c2ee8ea962 30 float frequency_final=((float)peak)/4.1;
melangeaddict 0:78c2ee8ea962 31
melangeaddict 0:78c2ee8ea962 32 return frequency_final;
melangeaddict 0:78c2ee8ea962 33 }
melangeaddict 0:78c2ee8ea962 34
melangeaddict 0:78c2ee8ea962 35 void FrequencyFinder::get_data() {
melangeaddict 0:78c2ee8ea962 36 if (index<size) {
melangeaddict 0:78c2ee8ea962 37 signal_array[index]=_signal_in.read();//-0.5;
melangeaddict 0:78c2ee8ea962 38 index++;
melangeaddict 0:78c2ee8ea962 39 }
melangeaddict 0:78c2ee8ea962 40 }
melangeaddict 0:78c2ee8ea962 41
melangeaddict 0:78c2ee8ea962 42 void FrequencyFinder::take_abs() {
melangeaddict 0:78c2ee8ea962 43 //takes the absolute value of the signal
melangeaddict 0:78c2ee8ea962 44 for (int j=0; j<size; j++) {
melangeaddict 0:78c2ee8ea962 45 signal_array[j]=abs(signal_array[j]);
melangeaddict 0:78c2ee8ea962 46 if (j<200)//~48Hz
melangeaddict 0:78c2ee8ea962 47 signal_array[j]=0;
melangeaddict 0:78c2ee8ea962 48 else if (j<400)//~97Hz
melangeaddict 0:78c2ee8ea962 49 signal_array[j]=signal_array[j]*3;
melangeaddict 0:78c2ee8ea962 50 else if (j<550)//~
melangeaddict 0:78c2ee8ea962 51 signal_array[j]=signal_array[j]*6;
melangeaddict 0:78c2ee8ea962 52 else if (j<900)//~219Hz
melangeaddict 0:78c2ee8ea962 53 signal_array[j]=signal_array[j]*10;
melangeaddict 0:78c2ee8ea962 54 else if (j<1200)//292Hz
melangeaddict 0:78c2ee8ea962 55 signal_array[j]=signal_array[j]*12;
melangeaddict 0:78c2ee8ea962 56 else
melangeaddict 0:78c2ee8ea962 57 signal_array[j]=signal_array[j]*30;
melangeaddict 0:78c2ee8ea962 58 }
melangeaddict 0:78c2ee8ea962 59 }
melangeaddict 0:78c2ee8ea962 60
melangeaddict 0:78c2ee8ea962 61 int FrequencyFinder::find_peak() {
melangeaddict 0:78c2ee8ea962 62 int i=0;
melangeaddict 0:78c2ee8ea962 63
melangeaddict 0:78c2ee8ea962 64 for (int j=0; j<size; j++) {
melangeaddict 0:78c2ee8ea962 65 if ((signal_array[i]-signal_array[i-1])>100 ) {
melangeaddict 0:78c2ee8ea962 66 while (
melangeaddict 0:78c2ee8ea962 67 (signal_array[i]<=signal_array[i+1]) &&
melangeaddict 0:78c2ee8ea962 68 (signal_array[i]<=signal_array[i+2]) &&
melangeaddict 0:78c2ee8ea962 69 (signal_array[i]<=signal_array[i+3]) &&
melangeaddict 0:78c2ee8ea962 70 (signal_array[i]<=signal_array[i+4])) {
melangeaddict 0:78c2ee8ea962 71 i++;
melangeaddict 0:78c2ee8ea962 72 }
melangeaddict 0:78c2ee8ea962 73 return FrequencyFinder::find_max(i);
melangeaddict 0:78c2ee8ea962 74 }
melangeaddict 0:78c2ee8ea962 75 i++;
melangeaddict 0:78c2ee8ea962 76 }
melangeaddict 0:78c2ee8ea962 77 return FrequencyFinder::find_max(i);
melangeaddict 0:78c2ee8ea962 78 }
melangeaddict 0:78c2ee8ea962 79
melangeaddict 0:78c2ee8ea962 80 int FrequencyFinder::find_max(int position) {
melangeaddict 0:78c2ee8ea962 81 int index1=position-20;
melangeaddict 0:78c2ee8ea962 82 int index2=position+20;
melangeaddict 0:78c2ee8ea962 83 float max=signal_array[index1];
melangeaddict 0:78c2ee8ea962 84 int max_index=0;
melangeaddict 0:78c2ee8ea962 85
melangeaddict 0:78c2ee8ea962 86 for (int a=index1; a<index2; a++) {
melangeaddict 0:78c2ee8ea962 87 if (signal_array[a]>max) {
melangeaddict 0:78c2ee8ea962 88 max=signal_array[a];
melangeaddict 0:78c2ee8ea962 89 max_index=a;
melangeaddict 0:78c2ee8ea962 90 }
melangeaddict 0:78c2ee8ea962 91 }
melangeaddict 0:78c2ee8ea962 92
melangeaddict 0:78c2ee8ea962 93 return max_index;
melangeaddict 0:78c2ee8ea962 94 }
melangeaddict 0:78c2ee8ea962 95
melangeaddict 0:78c2ee8ea962 96 void FrequencyFinder::initialize_array() {
melangeaddict 0:78c2ee8ea962 97 index=0;
melangeaddict 0:78c2ee8ea962 98 for (int w=0; w<size; w++) {
melangeaddict 0:78c2ee8ea962 99 signal_array[w]=0;
melangeaddict 0:78c2ee8ea962 100 }
melangeaddict 0:78c2ee8ea962 101 }
melangeaddict 0:78c2ee8ea962 102
melangeaddict 0:78c2ee8ea962 103 void FrequencyFinder::copy_data() {
melangeaddict 0:78c2ee8ea962 104 for (int i=0; i<size/2; i++) {
melangeaddict 0:78c2ee8ea962 105 signal_array[i+(size/2)]=signal_array[i];
melangeaddict 0:78c2ee8ea962 106 }
melangeaddict 0:78c2ee8ea962 107 }