Literature Survey on Dual-tone Multiple Frequency Dtmf Detector Implementation

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. There are many DTMF decoding algorithms, but most of them cannot comply with the related International Telecommunications Union (ITU) and Bell Communications Research, Inc. (Bellcore) recommendations and/or are not suitable for realtime implementation. In this survey a brief review of some DTMF detector implementations is given. Although the Goertzel Algorithm is not able to satisfy the standards, it was the best approach in the sense of computational load and memory usage e ciency. It might be possible to use the Goertzel Algorithm with variable window length to satisfy the speci cations. The aim of this project is to implement a DTMF detector, which is ITU complaint, on a xed point low cost DSP. This detector should be able to detect DTMF tones in multiplechannels with as much as possible channels.