Research On Overall Technology Of The Underwater Navigation And Location And Communication Incorporate System

Underwater acoustic positioning technique has been widely used in various fields of military and commercial projections. It can provide accurate position information for the application of oceanic exploitations and explorations. Being an important part of oceanic technology, acoustic positioning technique propels the developments and improvements of oceanic technology.Five parts are included in the dissertation: design and realization of a navigating and locating system as a whole, analyzing of the time delay estimation precision and the range which is the key factor to the system, Doppler measurement technique of underwater moving target, transponder position measurement technique, and validating the performance of the system by the trials.The system design idea is presented base on the analysis of the design requirement: The target navigating function is realized with the transponders deployed on the large area of ocean floor. The target positioning function is achieved by the combined operations of wireless remote controlling buoys on the surface and range finder on the mother ship. The management area of transponders is restricted due to the limited acoustic range, so that the combined remote control mode of wireless and acoustic communication is proposed, and the management and control of transponders in large area is realized. The construction design, navigation and location theories are proposed in the dissertation. Due to the functional specification, the acoustic signal processing method and the united communication scheme of radio and underwater acoustic are discussed.By the analysis of the navigation and location principle, the main factors that affect the system navigation and location precision are assured as the time-delay estimation error, array measurement error and sound speed measurement error. According as the discussion of the effects to location precision, the time-delay measurement scheme and array measurement scheme can be established. Analyzing the relationship between antenna height and radio communication distance in principle offers the theoretic basis. The function distance specification has been discussed. It is analyzed that the time-delay precision and system location precision can be achieved with the signal processing algorithm under the limit condition prescribed by the system specification.Doppler will be brought on the receiver by underwater target motion. A Doppler estimation method based on time delay measurements is proposed in the dissertation. With the method, the Doppler is estimated with high precision using time delay measurements of signal. The contrastive research has been done on the capability of Doppler estimation between time delay method and Notch frequency estimation method. The influence of the bandwidth and central frequency of ANF (Adaptive Notch Filter) on the processing gain is analyzed. The central frequency of ANF can be adjusted and the Doppler frequency can be tracked automatically. The method contributes to improving the signal processing gain and time delay estimation precision, and increasing the range. A model which can work out the velocity of the target by measuring the radial velocity is built, and can monitor the velocity of the underwater target.This underwater target navigation and location system is realized by the array elements deployed on the surface and floor of sea, with which the navigation and location precision is affected mostly by the position precision of array elements. The array elements position on the surface can be achieved by GPS, and the transponders deployed on the floor must: be calibrated in coordinate. In the interest of the transponders array calibration of large area, a new transponder positioning scheme with high efficiency and precision is provided combining direct and indirect measurements, and using the radio and underwater acoustic combination remote can avoid the ship sails long distance. With the variability of sound speed profile in the water, the irregular propagation of sound ray will bring out the ranging error and depress the transponder position precision. The ray acoustic segmental medium method for amendment of sound ray is adopted for improving the positioning precision, which is validated by simulations. Lastly, the design conceptions and principles of this system are introduced. The excellent performances are validated and exhibited by lake and sea trials, and the specification can satisfy the requirement. The feasibility and reliability of this scheme proposed in this dissertation are proved.