Audio Signal Transmission Based On LED Lighting Sources

As a new green illumination source, light emitting diode(LED) is considered to be the mainstream of next generation of lighting technology. At the same time it is also suitable for signal transmission for its splendid modulation characteristics. The application of LED visible light communication is not to replace the wireless communication, but for some special places, such as underground parking lot. The demand of lighting and communication is relatively strong, and the communication requirements are mainly reflected in using voice to guide the drivers entering the appropriate parking space in the parking lot. In order to solve this problem, a system of audio signal transmission based on LED lighting source was put forward in this thesis.The main contents are summarized as follows:(1)Analysis the main part of the visible light communication system, especially the LED source, which provided both theoretical and physical basis for the research.(2)Lighting environments were designed according to actual parking lot requirements. The suitable LED lamps were selected, and then relevant parameters were simulated by means of Dialux software. The results were confirmed to meet the international standard of illumination, and verified the rationality of the lighting design.(3) The LED audio transmission system was designed to finish the transmission of audio signals. Then verified the feasibility and reliability of signal transmission system.(4) Based on the existing laboratory conditions, the transmission distance of the LED audio transmission system in this work is less than 9cm, the effect in 4cm is best. The possible factors affecting signal transmission distances were analyzed, and improvement measures are proposed.(5)An improved binary coding method was proposed. The improved binary code method increased the transmission distances. And in the same distance, the error rate is lower than the ordinary binary coding method. In addition, using the improved coding method provides stable lighting environment without causing extra visual fatigue.The work is of valuable reference for LED based visible communications.