Study On Key Technology Of Shipborne All-in-one For Laser And Light Communication

Modern warship communication equipment including a variety of short, medium and long wave radio frequency communication and even the old light communication,has grown into a mature system. But with the progress of technology, the existing radio frequency communication had shown five major disadvantages: limited bandwidth, easy to reveal, and the complex decryption, strict channel management, susceptible to electromagnetic interference. Light communication also has disadvantages of low degree of automation, needed of professional sailor, lower communication rate. Shipborne all-in-one for laser and light communication is the best way to solve the above problems.Shipborne all-in-one for laser and light communication will unite the free space laser communication and the automatic light communication together. It based on the free space laser communication technology and the existing light communication, and was specially designed according to the characteristics of the Shipborne platform. Using laser communication terminal APT (Acquisition, Pointing,Tracking) system hardware to realize automatic light communication function, can make it compatible with conventional lights communication on the basis of wireless laser communication. In this paper, some key techniques of ship-borne optical camera is studied.The succeful case of international and domestic mobile platforms laser communication including shipboard was introduced as a design reference.The characteristics of shipboard wireless laser communication link was analyed. The impact of atmosphere on laser transmitting, the atmospheric absorption and scattering of laser, the light intensity fluctuation and the arrival angle fluctuation at the receiving end, and the influence of background radiation were introduced. Then the characteristics of the atmosphere close to the sea-surface was studied.It includes the relationship between atmospheric refractive index and height, wind speed, temperature, the change of season, location was showed. And the Close to sea surface atmospheric attenuation effect to the laser about height and time in one day was analysed. Finally the coupling efficiency characteristics of the multi-mode fiber in the receiving end was introduced.The APT system is a key technology to the laser-light communication all-in-one. The analysis to characteristics of ship rocking, and a simulation in simple case was done to refine the influence of the carrier platform to laser communication. The relationship between tracking-pointing error and optical power was showed, the comparition of two common APT structure was done. And there is a detailed description for the whole system,respectively from coarse tracking hardware, software, and hardware and software of fine tracking system. Finally, coarse and fine tracking information interaction and tracking-pointing error are analyzed.Light communication is another important feature of the optical communication all-in-one. Therefore the the sharing hardware and the different demand of the coarse tracking the light communication was discussed, and the part of image processing algorithms in the software was elaborated. According to the above system design, optical communication all-in-one APT system is established.The experiment about the performance of coarse tracking for rapid tracing, precision tracking of platform vibration by the fine tracking system, light communication and lighting during the day, night were tested. Results show that the coarse and fine tracking system were effective, respectively for compensation a wide range movement and the small angle jitter.The coarse tracking system can be effective to2.7°/SEC angular velocity target tracking, with0.017°residual.The main frequency of the residual was less than9hz. The fine tracking system was effective for a0.0158°and25Hz frequency jitter tracking. So it can deemed that the fine tracking system can compensate the coarse tracking system residual error. The light communication systems achieved15words per minute communication rate at a distance of3.5km.In the night it will not affected by constant disturbance light source. but greatly influenced by the background during the day time. the distance in May in the background light at noon can’t communicate very strong sunshine. The system may no work correctly under such a distance in a strong background light in a sunshine noon.