Time Delay Precision Measurement Technique Research Of GPS Sonobuoy

The high precision underwater DGPS positioning system we developed can be used to carry out the tracking, surveillance and dynamic positioning of underwater targets from the ocean surface, seashore or air. The GPS and underwater acoustic techniques are first combined in this system to realize underwater target navigation, instantaneous depth monitoring, underwater precision time service, underwater measurement control and underwater structure setting out. It integrates not only the DGPS positioning technique, but also sonobuoy, high precision clock and underwater communication techniques, satisfying the needs of underwater target positioning and navigation for long-term ocean exploitation and ocean high-tech development.GPS sonobuoys are the main components of the high precision underwater DGPS positioning system. They are positioned in real time by the dynamic GPS positioning technique, meanwhile to establish the surface measurement base-line for underwater positioning. As for the high precision positioning of underwater targets, the GPS sonobuoy technique has two bottlenecks: high precision system clock synchronization and high accuracy time delay estimation. The high accuracy time delay measurement technique for GPS sonobuoys presented in this thesis can be used to solve these two problems. It has already been applied in engineering practice and good results obtained.In the paper the principle of the high accuracy time delay measurement technique is analyzed, laying emphases on the simulation and methods adopted for key techniques. The development and design of the signal processing module and its signal processing board with double DSP chips are presented in detail. The realization of high precision system clock synchronization and high accuracy time delay estimation of positioning signals are described as well. The system performance has proved to be superior to what we expected.The high accuracy time delay estimation of positioning signals is verified through the analysis of the experimental results, which shows that the GPS sonobuoys meet the requirements of the system performance, featuring very high measurement accuracy.