Research On Visible Light Communication System Based On LED Display

Visible light communication mainly uses LEDs to emit visible light with modulation information and obtains information through photoelectric conversion devices to achieve communication.With the large-scale application of LED display screens,the use of LED display screens to multiplex communication functions can complete the secret transmission of information without affecting the display function,realizing the dual functions of communication and display.Existing visible light communication systems are mainly developed around LED lighting sources and visible light communication systems for LED display screens are still in the conceptual stage.Therefore,from the perspective of integration of communication and display,this paper builds a set of visible light communication system based on 64×64 LED display.The visible light communication system based on the LED display screen constructed in this paper mainly includes the design of the transmitter and the receiver.Both parts use the XC6SLX9-2TQG144C FPGA main control chip.The transmitting end completes the serial communication between the FPGA and the PC,the display signal input and the modulation of the communication signal;the receiving end completes the amplification and comparison of the detection signal of the detector,demodulation of communication signals and serial communication between FPGA and PC.At the receiving end,by comparing the APD detector and the PIN detector,PIN is finally selected as the receiving end detector and the waveform of the system is also verified and analyzed.The results show that the visible light communication system based on the LED display screen can transmit characters,files and pictures and other information while completing the display to realize the function of visible light communication.The system in this paper has been tested and verified that when the communication rate is 9.6kbit/s,the farthest transmission distance reaches 65cm and the bit error rate is lower than 5.5×10^-4.After the system is built,the light-emitting mode of the LED display screen is explored,and the influence of the LED display screen on communication under different light-emitting modes is further studied.Under the condition of full-pixel display,the background color of the display is debugged by using the FPGA software platform.The longest transmission distance of the system is increased to 140cm,and the bit error rate is lower than 2.5×10^-4.The angle between the transmitter and receiver should be selected to be<45°.The visible light communication system based on the LED display screen has the characteristics of rich display effect and secret transmission of information and can be applied to the fields of advertising media,information display,confidential communication,which has opened up a new application demonstration for LED display.