Visible light communication for audio systems

This paper describes an audio system that is well-suited for use in a small confined area with many audio transmitters broadcasting different audio signals. The transmitter of the proposed system is constructed using visible light LEDs, in which current fed to the LEDs is modulated and encoded with audio information or messages. The audio system provides audio signal transmission in a free space optical link. The receiver, combined with an ear jack, is located at some distance from the transmitters. The handheld receiver is designed to demodulate the optically transmitted audio information and reproduce the messages with the ear jack. For modulating emission of LEDs, an oscillator is used to vary the frequency of on/off periods of the LEDs. The frequency of flicker is high enough to be indistinguishable by human eye and hence the LEDs appear to be constantly illuminated.