const int sampleWindow = 100; // Sample window width in mS (50 mS = 20Hz)
unsigned int sample;

void setup()
{
   Serial.begin(9600);
}


void loop()
{
   unsigned long startMillis= millis();  // Start of sample window
   unsigned int peakToPeak = 0;   // peak-to-peak level

   unsigned int signalMax = 0;
   unsigned int signalMin = 1024;

   // collect data for 50 mS
   while (millis() - startMillis < sampleWindow)
   {
      sample = analogRead(14);
      if (sample < 1024)  // toss out spurious readings
      {
         if (sample > signalMax)
         {
            signalMax = sample;  // save just the max levels
         }
         else if (sample < signalMin)
         {
            signalMin = sample;  // save just the min levels
         }
      }
   }
   peakToPeak = signalMax - signalMin;  // max - min = peak-peak amplitude
   double volts = (peakToPeak * 5.0) / 1024;  // convert to volts
   if( volts < 0.02 ) {
      Serial.println("row: 0");
   } else if (volts >= 0.02 && volts < 0.30) {
      Serial.println("row: 1");
   } else if (volts >= 0.30 && volts < 0.60) {
      Serial.println("row: 2");
   } else if (volts >= 0.60 && volts < 0.90) {
      Serial.println("row: 3");
   } else if (volts >= 0.90 && volts < 1.20) {
      Serial.println("row: 4");
   } else if (volts >= 1.20 && volts < 1.50) {
      Serial.println("row: 5");
   } else if (volts >= 1.50 && volts < 1.80) {
      Serial.println("row: 6");
   } else if (volts >= 1.80 && volts < 2.10) {
      Serial.println("row: 7");
   } else if (volts >= 2.10 && volts < 2.40) {
      Serial.println("row: 8");
   } else if (volts >= 2.40 && volts < 2.70) {
      Serial.println("row: 9");
   } else if (volts >= 2.70 && volts < 3.00) {
      Serial.println("row: 10");
   } else if (volts >= 3.00 && volts < 3.30) {
      Serial.println("row: 11");
   } else if (volts >= 3.30 && volts < 3.60) {
      Serial.println("row: 12");
   } else if (volts >= 3.60) {
      Serial.println("row: 13");
   }

   Serial.println(volts);
}