Integrated System Of Underwater Image Processing And Transmission

Among the existing underwater information systems,underwater detection and underwater communication technologies are generally researched and designed as separate equipment.With the increasing demand for marine resource development and underwater environment monitoring,the imaging quality in the deep ocean environment decreases and the communication difficulty increases.There is an urgent need to research and develop integrated equipment for high-quality image acquisition and high-speed real-time communication.In this paper,based on the FPGA hardware development platform,the polarization image differential enhancement processing of underwater imaging and the image signal transmission of underwater LED wireless optical communication are carried out.By simulating the seawater environment,the sending end of the system uses polarized light illumination and liquid crystal optical rotation to obtain parallel/perpendicular analytical optical images in water,respectively.Using FPGA to realize differential enhancement processing of two images and PFM modulation of reconstructed image data,and realize stable transmission of the underwater channel through high-power blue LED modulation/drive circuit.The receiving end of the system realizes signal recovery through the optical receiving circuit,uses FPGA to perform digital filtering and PFM demodulation on the received signal,and transmits it to the PC end through the Ethernet for image display and storage.The main research contents of this paper are as follows:(1)The effects of light scattering of suspended particles in water on optical image signals and polarized light transmission were analyzed.Usually,the diffuse reflection of the target completely depolarizes the polarized light while the scattered light remains partially polarized.Therefore,the polarized light illumination is designed.The parallel/vertical analyzer receives the optical image and differentiates it so that the contrast of the image is significantly enhanced and the sharpness is improved.For this purpose,the polarized light images of parallel/vertical analysis are obtained respectively by liquid crystal optical rotation,and the differential enhancement algorithm for them is implemented on the FPGA.(2)Several commonly used optical communication modulation techniques are compared,PFM modulation technique using digital signal is determined,and a high-power blue LED modulation/driving circuit is designed.The integration of the image processing algorithm and PFM modulation technology is realized on the FPGA.Based on the previous research,the design of the transmitter system is improved.The underwater polarization image acquisition is integrated with the optical communication transmitter device.(3)Analyzed the performance requirements of the receiving end for the optical receiver,designed a reasonable optical receiving circuit and conducted a signal recovery test.The recovered signal was sent to the FPGA through AD conversion to realize digital filtering and PFM demodulation,the demodulated image data is transmitted to the PC through Ethernet(the transport layer is UDP protocol),and the display and storage of the image is realized by using the upper computer software.