extract frequency from samples series

It's been a long time since I did any signal processing but you might want to try doing a simple zero-crossing count.

For example, count the number of times the signal goes from negative to positive and divide by the number of samples.

int crossings = 0;

for(int idx = 1; idx < sample.length; idx++)

{

if((sample[idx - 1] < 0) && (sample[idx] >= 0))

{

crossings++;

}

}

int frequency = (crossings * sampleRate) / sample.length;

You can doubtlessly get even more complex but this may be good enough for reasonably clean signals.

Hope this helps.

KPSeala at 2007-7-9 18:21:27 >