Abstract: “Dual-tone Multi-frequency (DTMF) Signals are used in touch-tone telephones as well as many other areas. Since analog devices are rapidly changing with digital devices, digital DTMF decoders become important. In this survey a brief review of some DTMF detector implementations is given. The Aim of this paper is to implement a DTMF detector, which is ITU complaint, on a fixed point low cost DSP. This detector should be able to detect DTMF tones in multiple-channels with as much as possible channels. Microcontrollers, as the name suggests, are small controllers. They are also used in automobiles, washing machines, microwave ovens, toys .etc. where automation is needed.”

Keywords: DTMF, PWM, Path finder, Radio control , multifrequency