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c#algorithmaudiowave

Detect a specific frequency/tone from raw wave-data

I am reading a raw wave stream coming from the microphone.
(This part works as I can send it to the speaker and get a nice echo.)

For simplicity lets say I want to detect a DTMF-tone in the wave data. In reality I want to detect any frequency, not just those in DTMF. But I always know which frequency I am looking for.

I have tried running it through FFT, but it doesn't seem very efficient if I want high accuracy in the detection (say it is there for only 20 ms). I can detect it down to an accuracy of around 200 ms.

What are my options with regards to algorithms? Are there any .Net libs for it?

Solution

  • You may want to look at the Goertzel algorithm if you're trying to detect specific frequencies such as DTMF input. There is a C# DTMF generator/detector library on Sourceforge based on this algorithm.