Detection of tone signals using a nonlinear energy tracker

Abstract

Tone signals are widely used in communication devices to request the initialisation of a specific operating mode to the other side or to respond to it. For example, the operation of V.34 class voiceband modems is initialised by tone signals specified in ITU-T V.8 and V.25 Recommendations. These tone signals must be detected rapidly and accurately to enable a fast start-up. When tone signals are very narrowly spaced in frequency, the complex implementation. We propose a simple scheme for detecting these types of narrowly spaced tone signals. The proposed detector eliminates the need for sharp notch filters, by employing a simple nonlinear processor called Teagers energy tracker [l]. The detector is analytically designed and its performance is verified by computer simulation