White Led Wireless Digital Optical Communication Based On Cpld Experimental Research

Visible white LED wireless optical communication shows several advantagesover optical fiber communication and microwave communication, such as hightransmission power, no occupation of radio spectrum, no electromagnetic interference,no electromagnetic radiation, good secrecy and very low energy, etc. In visible lightcommunication system, LEDs may be used not only as signal sources for thecommunication, but also as light illuminators. Visible white LED wireless opticalcommunication may become the good choice for the indoor wireless broadband accessnetwork and outside intelligent transportation system. The paper aims solve someproblem existing in the white LED communication system. A CPLD-based indoorwireless optical communication system and wireless audio communication systemutilizing white LED is developed.In transmitter module, a digital signal source based on CPLD and LEDmodulation driving circuit is designed. In order to strengthen the anti-interference ofthe signal, the electric signal is coded with Manchester. In the receiver module, anoptical system is designed to overcome the inter-symbol interference produced bymulti-path effect. In order to suppress the background noise, a receiving circuit and adigital signal processing circuit are designed. The processor is designed in CPLD toimplement the Manchester coding. Code element synchronous extraction, burrelimination and experiments are done with the developed visible white LED opticalcommunication system. The measured maximal distance is48cm for the digital signalcommunication. The measured communication data rate is300Kbit/s. On the basis ofthe visible white LED wireless optical communication, the wireless audiocommunication with up to256Kbit/s data rate is realized between two PCs.