I had a similar issue with some 'random' noise spikes on the signal which I wanted to eliminate. The usual smoothing and moving avg approaches I found when searching for solutions did not match my expectations as the noise would still distord the results.
So, I created some kind of of a gauss filter, using a scatter recording approach.:
the code is still a bit rough but does it's job.
I get 10 readings, record them in an array thay counts how ofter a given value is found and pull then the value that got most hits;
#define sampleSize 10
int sampleArray[sampleSize + 1][2] = {{0}}; // initialise array
Sorry for being lazy...
I know it's not optimal but I like the easy way of using real references for adressing the array, ie 1st record sits in array[1]
push () records the values and increments the counter for a given value:
void push (int val) {
short i = 0;
for (i = 1; i <= sampleSize; i++) {
if (debug) Serial.printf("%i-%i: %i #%i\n", i, val, sampleArray[i][0], sampleArray[i][1]);
if (sampleArray[i][0] == val) {
++sampleArray[i][1];
return;
}
else if (sampleArray[i][0] == 0) {
sampleArray[i][0] = val;
++sampleArray[i][1];
return;
}
else if (i == sampleSize) Serial.printf("ERROR - too many values: %i\n", i);
}
}
and pull() returns the value with most hits:
int pull() {
int maxCnt = 0;
int maxVal = 0;
short i = 0;
for (i = 1; i <= sampleSize; i++) {
if (sampleArray[i][1] > maxCnt) {
maxCnt = sampleArray[i][1];
maxVal = sampleArray[i][0];
}
}
return maxVal;
}
since I wanted to simplify the tests, I did not even use a data source but simply used random numbers.
int readValue() {
short i = 0;
// reinit array
for (i = 1; i <= sampleSize; i++) {
sampleArray[i][0] = 0;
sampleArray[i][1] = 0;
}
for (i = 1; i <= sampleSize; i++) {
//push(AnalogRead(ADC));
push(random(20, 35));
}
return pull();
}
my main loop calls the readValue() and sends it to an IoT cloud - now lukily with out anymore with the spikes I ahd before.
I use the code now in different sketches for data capturing and it works perfectly fine :-)
