Tricolor light-emitting diode dot matrix display system with audio output

In this paper, a novel tricolor dot matrix display system in which all the light-emitting diodes (LEDs) are modulated and encoded with audio informati on is presented. The novelty is on the concurrent use of the tricolor LED d isplay for simultaneous visual message display and audio signal transmissio n in a free-space optical link, This is a new generation of tricolor dot ma trix displays where, in addition to the usual function of LED display, they concurrently provide audio broadcasting through the visible light rays tra nsmitted by the display panel or assembly,The system is comprised of a tric olor dot matrix display panel with an interface circuit to a computer, an a udio signal transmitter, and a receiver, It also comprises an executive pro gram that runs on the computer for the display control of characters, decor ative pattern or messages on the display panel. The receiver is designed to demodulate the optically transmitted audio information, and reproduce the messages with the speaker. For modulating emission of the LEDs, an oscillat or is used to vary the frequency of on/off periods of the LEDs, The frequen cy of flicker is high enough to be indistinguishable by human eye and, henc e, display appears to be constantly illuminated.