| With the rapid development of global satellite navigation system, the navigation technology which is compatible with different system is bound to become an important trend in the future. Comparing with single-mode navigation system, multi-mode satellite navigation system has more advantages, for instance: a large numbers of visible stars, more coverage, highly positioning accuracy and so on. This thesis mainly studies the key technology in dual-mode navigation system which is compatibles with BD and GPS.Firstly, this thesis describes the composition of two system and analyses compatibility and interoperability between BD and GPS. From the basic structure of signal the paper analysis three traditional algorithms. In order to improve the speed of capture further, this paper proposes an algorithm which is based on the parallel code phase method and takes advantage of cycling shift methods by reducing the number of calculations in FFT to improve the efficiency of capturing.Secondly, according to the features, in dual-mode navigation system it has a number of visible satellites. This paper puts forward a modified BD/GPS system algorithm based on the existing single system satellite selection algorithm, under conditions to ensure the feasibility of the algorithm by choosing the best constellation to improve the accuracy of positioning.Thirdly, based on principle and calculating method of the traditional single positioning system, the paper on the basis of further improves the observation equation and makes some correction on the Error-source, proposed in an integrated navigation positioning system of BD/GPS decoding to gain the positioning results of dual-mode combination system.Finally, using the actually collected GPS-L1 and B1 I signal on MATLAB platform, the paper studies on the theory and the method is verified and analyzed. From the capture results, positioning results, GDOP value, location coordinates range and many other angles, the algorithm of this paper is verified. Verification results showing that the above methods of capture method and satellite selection algorithm can really improve efficiency and accuracy of dual-mode navigation system. |
