AN2122 - Analog - Standard - DTMF Detector

AN2122 describes the implementation of a dual-tone multiple frequency (DTMF) detector. This application note shows how to build an inexpensive decoder that satisfies most ITU requirements and consumes relatively low CPU resources to be operational in the background, while being able to distinguish speech and music from a valid DTMF signal.

Introduction

DTMF signaling is widely used in analog telephone dialing, data entry, voice mail systems, remote control of various consumer electronics (auto answering machines, home automation devices, bank information services, etc.).