Study On Application Of City Traffic Guiding System Based On High Lightness LED

With the rapid development of the economy, Energy-saving and environment- protection and high-efficiency LED road lights were largely installed already. Moreover, LEDs own good modulation feature, fast modulation speed and huge transmitted power. They can be used for visible light wireless communication devices. In paper, we build an urban voice traffic guiding system. The variable traffic and road information are supplied to the vehicles and pedestrians through the system, to ease the happening of road congestions and accidents, and ensure the people’s safeties. The system plays an important part in the intelligent transportation system.On the basis of LED illumination, the urban traffic guiding system based on white LED was built using the modulating characteristic of LED. There are three aspects to study the reliability performance of the system. Firstly, some important parts including LED lighting device, LED drive circuit, wireless optical communication system, road illumination, and voice synthesis technology and so on were analyzed in detail, in order to design the urban voice traffic guiding system. The diversity technology was adopted to reduce the influences of Rayleigh fading and multipath interference and shadow of the communication system. Secondly, according to the theoretical analysis, the hardware circuits of emitting and receive were designed in protel 99. And the voice signal is synthesized by SYN6288 chip. The emitting system included TL494 PWM pulse driver and DD311 constant current driver to ensure lighting and communication of LEDs. The receiver system included 16 PIN array detectors to receive information and AGC circuit to ensure the stable output signal. Finally, we used the experimental platform to prove the feasibility of system. On the basis of simulation parameters and road illumination standard, single tube receive was designed to compare with Equal Gain receiver.The results proved that the Equal Gain array receiver could amplify angle of the receiver, to improve the sensitivity of receiver. The AGC circuit and amplitude-limiting circuit could increase the dynamic range of receive system and ensure that the volume of output voice single was stable.The theoretical analysis results and experiment results proved that the study of urban voice traffic guiding system based on LED road light is feasible and safe, to supply a new guiding way to the intelligent transportation system.