Description

In various types of telecommunication systems there exists a voice-operated switch known as VOX or Voice Operated eXchange. This switch allows the user to open a channel for communication without the need for a mechanical switch or push-to-talk (PTT) switch resulting in a hands-free device activated by the voice. This voice-activated switch is especially useful for aircraft radio and intercom communication, specifically for the pilot in which a hands free device is needed.A successful Dynamic VOX circuit improves the triggering of the switch by filtering out background noise and distinguishing between the human voice and environmental noise while not clipping the original voice signal. The purpose of thisproject is to develop a new and novel Dynamic VOX algorithm implemented with analog and digital circuit design that accomplishes this.

The following image (Figure 1.) represents a depiction of how a voice operated exchange functions. The user's voice will likely be mixed with a high-level background noise. Therefore the first stage in the VOX device will contain a noise cancellation board that will filter out any noise that exceeds the typical bandwidth of human speech (300 Hz to 3 kHz). Stage two sends the filtered signal into the VOX circuit which will distinguish between human voice and background noise and open the channel for communication if a human voice was indeed received. From this point a channel will be open for communication until the user stops speaking in which the channel will then close.

Problem Statement

The goal of this project is to develop a Dynamic VOX algorithm implemented with analog and digital circuit design that improves the triggering of the voice activated switch by distinguishing between human voice and background noise while not truncating the original voice message.

Last Updated 02/16/14