Design Of Adaptive Receiving Circuit In Wireless Ultraviolet Scattering Signal

Ultraviolet(UV)communication is a kind of wireless optical communication technology which uses ultraviolet light as the information carrier and transmits information in free space.It has a series of unique advantages,such as non-line-of-sight(NLOS)communication,strong anti-interference ability,low position discrimination and all-weather work,it has been widely concerned by researchers at home and abroad.Diversity reception and Automatic Gain Control(AGC)technology are widely used in radio frequency communication.Diversity reception technology is an effective anti-fading technology,which can greatly improve the transmission reliability of communication system in multipath fading channels.AGC can adjust the received signal adaptively to avoid signal distortion caused by the strong and weak changes of the received signal and reduce the influence of the channel change on the communication system.In order to improve the performance of wireless ultraviolet communication system,this paper combines the diversity receiving technology with the AGC,and designs an wireless ultraviolet scattering signal adaptive receiving system.The specific research contents are as follows:(1)According to the NLOS communication link model of wireless ultraviolet light,the probability density function of the intensity edge distribution of the received light signal is established,and the model of wireless ultraviolet light NLOS communication system is modified.The Bit error rate formula of the Maximal Ratio Combining(MRC)?Equal Gain Combining(EGC)and Selection Combining(SC)three combination mode is derived,and the simulation analysis is carried out in ultraviolet light NLOS communication system.The simulation results show that the performance of MRC,EGC and SC is improved by three kinds of signal-to-noise ratio(SNR)of 22 dB,18dB and 16 d B respectively.It can be seen that t he performance of MRC is the best,EGC Worse and SC is the worst.(2)The characteristics of the automatic gain control system are combined,and an automatic gain control amplifier is designed for the wireless ultraviolet light NLOS communication diversity receiving system.The software and hardware of each module of the amplifier are designed,and the actual test was carried out in the outdoor environment.The results of the experiment coincide with the simulation results.The experimental results show that the output of the amplifier is basically stable near the preset value.The application requirements of wireless UV NLOS communication diversity receiving system are achieved.(3)An ultraviolet communication test platform is established,The SNR performance of the adaptive receiving system is tested.In the case of different receiving angle and communication distance,the system can not only improve the SNR of the received signal about 2dB,but also improve the stability of the received signal.