Research On Key Issues Of Intelligent Signal Light System Based On Visible Light Communication

Visible Light Communication(VLC)is a wireless communication method that uses LED light source as a transmitter and air as a transmission medium to realize lighting and communication simultaneously.This paper,starting from the intelligent street lamp system based on visible light communication,studied the key issues in the system,such as modulation method,LED driving system and high frequency data modulation.The main work done as follows:1.The paper firstly analyzes the light source characteristics of white LEDs from the aspects of volt-ampere characteristics,power characteristics and modulation characteristics.By comparing the advantages and disadvantages of different modulation methods and the applicable range,the IEEE 802.15.17 recommended variable pulse position modulation(VPPM)is used.2.In order to better realize the dual functions of optical communication and LED lighting,the transmitter and receiver circuits of the system are designed.At the transmitter side of the system,a unipolar LED driver circuit scheme is proposed based on the VPPM modulation scheme,and the specific control circuit schematic is given.At the receiving end of the system,the circuits including preamplifier,band-pass filtering and output amplification were analyzed and designed,and software simulations were performed for each part.3.From the consideration of lighting and visible light communication effects,this article revisited the installation height and angle of signal lights.4.Finally,a physical model of the entire system was built to verify the experiment,and the experimental results that can verify the correctness of the system were obtained.The research method of this paper is based on the combination of theoretical analysis,circuit design software simulation,and a simple system physical object is established to verify the research method of this paper.