Revision 2:ef6c30f459a5, committed 2016-10-25

Comitter:

Jankoekenpan

Date:

Tue Oct 25 15:00:21 2016 +0000

Parent:

1:d357a1e80389

Commit message:

calculate standard deviation from the whole signal

Changed in this revision

--- a/main.cpp	Tue Oct 25 14:12:40 2016 +0000
+++ b/main.cpp	Tue Oct 25 15:00:21 2016 +0000
@@ -18,6 +18,9 @@
 //BiQuad bq4( 1.00000e+00, -2.00000e+00, 1.00000e+00, -1.97996e+00, 9.80645e-01 );
 //BiQuad bq5( 9.97389e-01, -1.97771e+00, 9.97389e-01, -1.97771e+00, 9.94778e-01 );
 
+volatile float TOTAL_SAMPLE_SUM = 0;
+volatile long NUMBER_SAMPLES = 0;
+
 const int numEmgCache = 50;
 float emgCache[numEmgCache]; //sorted from new to old;
 
@@ -56,8 +59,7 @@
     return sum(array, size) / size;
 }
 
-float variance(float array[], int size) {
-    float avg = mean(array, size);    
+float variance(float array[], int size, float avg) {  
     float squaredDifferences[size];
     for (int i = 0; i < size; i++) {
         float difference = array[i] - avg;
@@ -66,12 +68,12 @@
     return mean(squaredDifferences, size);
 }
 
-float standardDeviation(float array[], int size) {
-    return sqrt(variance(array, size));
+float standardDeviation(float array[], int size, float avg) {
+    return sqrt(variance(array, size, avg));
 }
 
-int decide(float signalvalue, float threshold) {
-    return signalvalue < threshold ? 0 : 1;
+int decide(float value, float threshold) {
+    return value < threshold ? 0 : 1;
 }
 
 
@@ -81,8 +83,12 @@
     float filtered = movingAverage( fabs(emg) );
     scope.set(1, filtered);
     
+    TOTAL_SAMPLE_SUM += emg;
+    NUMBER_SAMPLES++;
+    
     addFirst(filtered, averageCache, numAvgCache);
-    float stdDev = standardDeviation(averageCache, numAvgCache);
+    float avg = TOTAL_SAMPLE_SUM / NUMBER_SAMPLES; //TODO calibrate this value.
+    float stdDev = standardDeviation(averageCache, numAvgCache, avg);
     scope.set(2, stdDev);