Design Of Short-Distance Ultraviolet Communication System And Its Realization Based On FPGA

Ultraviolet communication is a new kind of communication techniques in free space optics communication field. Some excellent performances such as safety, anti-interference, non line-of-sight, make it different from other communication models. Hence, ultraviolet communication can be applied in some special occasions to make up for the shortage of traditional communication models.While the light is transmitted through the atmosphere, due to oxygen and ozone in it, ultraviolet light whose wavelength is between 200nm and 300nm is almost absorbed after it is transmitted to earth. Ultraviolet light whose wavelength is between 200nm to 300nm is called solar blind ultraviolet light. As a result, if this ultraviolet light is used for communication, it has little background noise. Meanwhile, NLOS communication in a specified range is possible due to its strong scattering characteristic, which is considered another advantage to other communication models.First of all, ultraviolet communication theory and transmitting characteristics are analyzed, and the main factors which influence UV communication are stated.Secondly, according to the special characteristics of UV light, a short range UV wireless communication system model is proposed. The selection of key parts of the system and modulation/demodulation solution is also discussed. UV LED is chosen for low power consuming and small volume. PMT is picked as it is high cost-effective. OOK and PPM modulation modes are selected for it is simple and has high performance. DPPM and DPIM are considered as supplemental modulation modes and will be realized in future.Thirdly, transmitter module and receiver module based on OOK/PPM is realized and simulated in QuartusⅡ. Moreover, realistic measurements bases on Altera FPGA are performed and experiment data is collected.The purpose of this program is to utilize the current technologies to do some elementary research on UV communication. In present, the system with low power supply (lower than 1mW) can transmit character information at the rate up to 9.6kbps in a short distance with a low bit error rate. This program accumulates experience for the later real time UV speech communication research.