SYSTEM FOR DETECTING VOICE ACTIVITY IN A COMMUNICATIONS SIGNAL

A system for detection of voice activity in a communications signal, employing a nonlinear two filter voice detection algorithm, in which one filter has a low time constant (the fast filter) and one filter has a high time constant (the slow filter). The slow filter serves to provide a noise floor estimate for the incoming signal, and the fast filter serves to more closely represent the total energy in the signal. The absolute value of incoming data is presented to both filters, and the difference in filter outputs is integrated over each of a series of successive frames, thereby giving an indication of the energy level above the noise floor in each frame of the incoming signal. Voice activity is detected if the measured energy level for a frame exceeds a specified threshold level. Silence (e.g., leaving only noise) is detected if the measured energy level for each of a specified number of successive frames does not exceed a specified threshold level. The system enables voice activity to be distinguished from common noise such as pops, clicks and low level cross-talk.