Research On Anti Multiplepath And Anti Range Ambiguities Technology In Long Baseline Acoustic Tracking System

Torpedo positioning/tracking system for the naval range is a special group of the acoustic location system. Four generations of the portable active Torpedo positioning/ tracking system for range have been developed in our naval range until now. The engineering background of this paper is the fourth generation GRAT system. Its focus is to research the multiple path and anti range ambiguities problems in long baseline acoustic tracking and positioning system.GRAT is an acoustic positioning/tracking system with both synchronous and asynchronous compatible work modes. Its main task is to track and position the multi underwater maneuvering targets or fixed targets accurately. The positioning principle is to measure the propagating time or time difference that the range measuring impulse in double pulse signal radiates to every receiving buoy array units firstly, then to determine the horizontal position of the target at the time of projecting by spherical or hyperbolical join and to gain the depth of the target through double pulse depth remote measurement decoding. Variance of Instantaneous Frequency is applied in order to prevent the leakage from the other frequency channels. Therefore estimates of the propagating time and frequency are very important parameters for position calculating and signal observing and measuring.The influences that the interfacial reflection acts on the positioning algorithm behave as the influences that the phase-coherent multiple path channel acts on the signal parameters such as propagating time, frequency, phase and amplitude. The dissertation researched the theory about it and completed simulation analysis. Most actual systems apply narrow-band pulse signal of 1~2ms to avoid the above influences as best as possible. It is necessary for GRAT expert system to possess the ability of anti multiple path ambiguities. That's to say that the system should be able to select a pair of effective range measuring pulse and depth measuring...