Research On Long Base Line Underwater Target Navigation And Orientation

The underwater acoustic orientation basing on geometry principle is the main technique of underwater target navigation and orientation. Under the background of Long Base Line Underwater Target Navigation and Positioning System (LBL), the dissertation discusses its key technique, researches on the wireless telecontrol base station and the PC software.The LBL system is compatible with synchronous and asynchronous work style. It can use spherical (synchronous) or hyperbolical (asynchronous) join to compute the target's position precisely, and track in a wide area. The system contains wireless and underwater acoustic communication net, which former adopts DSSS and TDMA technique and the latter adopts digital BFSK mode. It uses multiply parallel adaptive Notch fitters to receive different frequency CW pulse signal. The signal detecting ability improved by adopting the united detector which includes the Variance-of-Instantaneous-Frequency Detector (VIFD), the Energy Detector and the Width Detector. The united detector has evident effects on reducing the problem of pulse-interfere and the frequency leak between near channels.The wireless telecontrol base station is the hinge of the communication net. The dissertation introduces a DSP+FPGA structure for base station, chooses DSSS transmitter-receiver and DGPS receiver to communicate and self-position. The application of FPGA reduces the complexity of interface design and the scale of hardware.The PC display and control software design is another important work of the dissertation, which is developed on the Visual C++ 6.0 kit. For the convenience of software's development, debugging and servicing, The software is composed of many blocks, every block is independent. Expert and preventing distance confusion is the most important arithmetic, the dissertation adopts the unite of show of hands and original position initialization, this arithmetic is simple, and can re-tracking while interrupted.