The Designing And Realizing For Communication With Ultraviolet Light

As a new communication mode, more and more scholars have drawn attention to opticalcommunication. Compared with the conventional radio, the communication distance isrelatively closer, but it has higher security with respect to hardly eavesdropping and tracking.Taking into account the shorter UV wavelength which is easy to scatter, non-line-of-sightcommunication could be achieved within a short distance.This provides possible applicationsin complex geographical environment. Additionally, the implement of solar-blind ultravioletas a communication medium could make it a24-hours continuously for local communication.As a consequent, it is very suitable for ships and helicopter.This topic focus on the working wavelength of255nm UV light, which incoming energyon the earth surface was absorbed by ozone mostly. Based on the assumption, there is noobtrusive light in the communication environment. Then, we can product Low-Bit Error Rateof communication with low power. This paper presents the LOS and NLOS communicationlink model, the analysis of the relationship between the path loss, bit error rate, and thecommunication distance.Ultraviolet light sources based on ultraviolet light-emitting diodes present severaladvantages: they are small on the volume, simple to manufacture, easy to drive, relativelyhigh power output and when the photomultiplier tube is used at the receiving end, theworking waveband corresponds directly with the ultraviolet region. In this paper, we adoptthe digital communication mode which requires accuracy control to sequential logic. Basedon the above, FPGA is selected to realize the modulation and demodulation for ultravioletlight. Through the experiment research, the communication system could achieve low errorrate communications within100meters with the respect to traffic rate at600kHz. Thecommunication system, including hardware drive circuit, receiving demodulation circuit, thesoftware designed for the system and the algorithm of bit error rate has been investigated indetail in this paper.For some shortcomings of the standard PPM modulation, the topic presents theimproved PPM code modulation that this method promotes the output power of light sourceand also increases system reliability. After test, it shows better performance, meanwhileachieves a relative long-distance communications.