If you’ve ever wondered about the best way to detect dial and DTMF tones from a phone line, [Debraj] is your man. [Debraj] built a DTMF detector using the Goertzel algorithm. Normally, when w… ...

On the receiving side, DTMF tones are easy to decode — at least now. We’ve got DSP chips to do the job all in one package, or we could roll a simple circuit from phase-locked loops.

DTMF digits are frequency combinations that enable tone dialing on the PSTN. Pulse dialing was historically used with rotary phones. Voice over IP systems have many methods to leverage DTMF digits ...