| This thesis is focused on how to convert the time-difference into the geographical coordinate in Loran-C navigation system. The paper first introduces the basic principles of Loran-C navigation system and the research situation at home and abroad. It also analyzes the radio hyperbolic positioning principles and the method of ASF Revise. Secondly, based on mathematical models, the paper presents the formula manipulation of the single-chain direct solution and multi-chain direct solution. It studies the paranormal phenomena and the multiple-valued problem while calculating the approximate position, and puts forward a method of time-testing for solving the multiple-valued problem. So the approximate position can be calculated simply with 3 time-differences, improving the Loran-C receiver. Next, the iterative algorithm of the latitude and longitude is presented, with data analysis according to geographical position. Finally, the dissertation gives the system structure of digital Loran-C receiver, designed by DSP & FPGA, and the designing flow of the position-calculating module, hardware-implemented by DSP. The system is tested and some positioning-curves are presented. |
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