The Design And Realization Of Underwater Non-contact Communication System Based On Inductively Coupled Link

Because of the Sharply increasing world population, substantially reducing land resources, and seriously increasing environmental pollution today, the exploitation of world's oceans has become a major theme in the development of marine science and technology, developing the marine technology, in particular, the marine high-tech has become one of the most important content of world's new technological revolution, and the marine environmental monitoring technology as the technical basis of modern marine development is the major component of marine high-tech.In view of this situation, the subject will develop a set of unattended fixed vertical profile of automatic monitoring system getting energy form ocean wave, access to fixed vertical profile of the environmental parameters of marine data for the further development of marine resources, protection of the marine ecological environment and disaster prevention and reduction to provide wealth of reliable information and data. The main part of the underwater platform of system and the floating-body will be designed separately, if using wire communication to achieve, then because the communication range due to the ever-changing, design will be difficult and security of transmission line equipment and communications reliability can not be guaranteed. Therefore, the profile of non-contact observation data transmission technology research is a key technology for this project.The main work of this graduation project is to develop a set of non-contact transmission system used in the cross-section of this issue of data non-contact data transmission.Using electromagnetic coupling theory, and on the basis of the studying the coupling of the coil electromagnetic theory and the transmission characteristics of seawater, by choosing the appropriate communication speed, carrier frequency and modulation and demodulation method, the paper developed a set of underwater non-contact communication system based on magnetic coupling. The whole system is divided into three parts:(1)Transmitting circuit. Mainly used to modulate the useful signal on carrier on the ASK mode, after power amplification, and convert the use of the electrical signal to magnetic signals by resonance and send it out through the coupling coil, which consists of a level shifting circuits, and RS232 interface circuit and so on.(2)Receiving circuit. Mainly used to receive magnetic signals through coupling coil and convert it to electrical signals by resonant and carry out amplification, filtering, demodulation, filtering, Schmitt trigger and a series of treatment ultimately received modulated signal to restore the usefulness of the original signal and reception.(3)Control circuit. Sending circuit and receiver circuit share a coupled coil, which needs to design the control circuitry so that the whole circuit work in half-duplex manner, the article choose C8051F020 having two serial ports as the control chip, and through the design of hardware circuits and software, the whole system works in half-duplex manner.In the system debugging process, we carried out the laboratory to transmitting and receiving circuit debugging, an underwater simulation environment for debugging, the control circuit debugging, as well as overall system debugging, the ultimate successfully implement the system functions.The whole system achieve the underwater distance of two coupled coils 20cm, axial angle of less than 60°, 9600bps baud rate no-error transmission, entire system consumes 300mW, in line with the requirements of the whole issue.