Arduino pitch detection in realtime (using autocorrelation and peak detection)

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48

Hi,

The code below shows the changes that I made to find not only the first but also the second correlation peak. Both the frequencies that belong to these periods are calculated (not in the code fragment).

case 2 :
        if ((currentSum - previousSum) <= 0) {
          float interpolationValue = 0.5 * (currentSum - twoPreviousSum) / (2 * previousSum - twoPreviousSum - currentSum);
          if (firstPeriod == 0) {
            firstPeriod = i - 1 + interpolationValue;
            break;
          }
          else {
            secondPeriod = i - 1 + interpolationValue;
            pdState = 3;
          }
        }
        break;

A question out of curiosity, would it be possible to get the same accuracy with FHT or FFT libraries on the Arduino (with interpolation added)?

Bart