Offshore To Dives Communications System's Research Based On The OFDM Underwater Sound Communication Establishment

The development of modern military technology brings Marine militarytechnology development,in the same way, Marine military technology developmentalso contributed to rapid development of the underwater communications technology.In order to strengthen the control over the ocean military field and gain the initiativeposition in seaborne struggle and resources war in the future, every military power inthe world begins to develop submarine technology one after another. And thedevelopment of submarine technology necessarily leads to the development of divecommunication technology. Dive communication system is a kind of advancedcommunication mode in recent years which all countries scramble to develop andresearch. Therefore, studying the advanced dive communication system not onlyattaches important significance in the part of enhancing our country's seaborne ability,but also a demand in national defense modernizationThe major military powers in the world such as the United States, Britain, Franceand other major western countries and Russia etc, the former Soviet union havewidely used dive communications technology in military terms. In our country, thecurrent main dive communications technology still is some old mode ,such as buoyscommunication which are poor in safety and reliability. Yet our country has notestablish a good communication mode, such as VLF-em dive with extremely lowfrequency remote communication, etc. In order to remedy this one blank ,it is aninevitable trend to make full use of modern acoustic research of advanced technology,and develop a set of advanced to submarine communication system.In this connection, the paper is to design a kind of dive communication systemadapted to the offshore defensive system planning of our country ,with the acousticchannel as the transmission carrier in the communicaiton system transmitting thesignals via sound wave. The offshore to submarine communications system studyed in this paper is able to accomplish the communication among command and control center , submarines, and surface warship via underwater launch/receiving system, and the underwater routing transponders. To ensure the demand for security, the encryption of signal tactics guarantees the signal will be received with safty and won't be decrypted by. enemy. Duing the war, due to the integrity of the system ,the communtion can be still accomplished via the intensive launch/receiving stations even if one or two of the launch/receiving stations is destoried by enemy which help to achieve the purpose of reliable communication. In modern warfare, the second attack ability is an effective tools to guarantee the war balance in which submarine plays an essential role. Since our current submarine technical level is still not perfect, the submarine can't get through the first archipelago of submarine scope .Therefore, strategic defense is the main direction in whole military war. Based on this, reliable offshore dive communication is the major method to the guarantee the real-time communication which ensures the security and reliability of the second attack and the purpose of deterrence.In the part of "Based on the OFDM acoustic communication technology to build offshore dive communication system"include four section: land command center, underwater launch/receiving stations, routing stations and the submarine. This paper is mainly the study on the underwater acoustic communication system. The main task is to research how to use sound waves to realize the reliable communication between command and control center on the land and the submarine. In order to guarantee the reliable communications, the distance between the submarine to the underwater launch/receiving stations or nodes router should be no more than 200KmThis paper studies the necessity, domestic and international system dynamic analysis of relevant research using and system research ideas and system realization method of the aspects of the design of the whole system, has made the detailed analysis and research on the basic theory, general following the advanced, safety and reliability criteria. Rightness dive communication system was fully each part of the principle analysis, mainly from combat performance and reliability into consideration, completed the transmission receiving part of hardware design, achieved the objectives of the study. The main research work include: acoustic technology theory research; The analysis of underwater acoustic channel model calculation; OFDM basic principle and application of analysis; To submarine communication system of general design; To submarine communication system of hardware design; Transceiver system instruction encoding design; Routing repeater design, etc.The main research results obtained are:1.According to design requirements of offshore dive submarine communication system, analyzing the sound wave propagation in water. At present, the communication distance in underwater acoustic reached above 200m which provide dive communication system design with reliability standards;2.Completes the theory calculation of acoustic channel model. The analysis of the underwater acoustic channel model and the calculation and analysis in the physical model, the mathematical model, the noise model, and reverb model provide the realization of offshore communication system with provides a feasible basis.3. Realizing general scheme design of the offshore dive communication system The system consists of four parts, including land command center, underwater launch/receiving stations, routing stations, submarine, among which the underwater launch/receiving system is the core of this paper.This design scheme of the system has the innovation and advancement mainly as below:The system is designed based on sound waves, in which ,the transmission distance reaches to 200km. The introducing of the node routing transponders improves the communication distance greatly and expands the combat radius distance of submarine which also fills the technology blank of our country in this field.The introduction of the OFDM orthogonal frequency division technology, greatly improves the anti-disturbance performance of the system and achieves the purpose of real-time communication. Stable Meanwhile, it also solves the inter-symbol interference through the equalization technology.Complete the design of the overall hardware in offshore dive communication system by applying modern digital signal processing and electronic control technology to improve design in the level of offshore defensive.