Underwater Portable Video Communication System Based On Blue Light LED

Underwater visible light communication (UVLC) is an emerging underwater wirelesscommunication technology, which plays a crucial role in monitoring the marine environment andmarine military affairs. UVLC has the following advantages: it is suitable for high-capacity datatransmission; it has strong anti-interference ability; its transmission delay is small; it has goodconfidentiality; its communication devices are small. UVLC also has its disadvantage that it is onlysuitable for short-distance underwater transmission.The main work of the paper is as follows:(1) The transmission characteristics of underwater visible light are analyzed. The lighttransmission attenuation model is established. Based on four types of waters, the relationshipbetween the visible light attenuation coefficient and the wavelength of visible light is analyzed, andthe visible light waves which are suitable for transmission is obtained.(2) As blue light has good transmission characteristics in deep clear waters, a low cost, smallsize blue light video communication device is designed. The system uses a PIN silicon photodiodeas a light receiver, and the beam is focused by optical lens, so that the system’s farthestcommunication distance is1.8m in the air.(3) The light intensity distribution and received optical power distribution of the system inthree types of waters are analyzed. Based on the obtained Seawater channel model, a performanceanalysis method for the UVLC system is established, it provides guidance for the system design andsystem performance evaluation. When the angles of divergence are different, the systemperformance is compared; the results show that the optical lens is very important.(4) Some salt and a small amount of particles are added in a laboratory tank to make the saltconcentration of the simulated seawater being3.6%. Through the experiment, the effect of visiblelight video transmission is observed and analyzed; the system noise sources are explored; therelationship between receiving SNR and the transmission distance is simulated, and the theoreticalmaximum transmission distance of the visible light vedio communication system is obtained;several ways for impoving system performance are analyzed.