Research On Positioning Solution Technology For GPS And BD Dual-mode GNSS Receiver

Nowadays GNSS (Global Navigation Satellite System) is widely used in communications, surveying, military and et al. And the application range of GNSS continues to expand. Taking consideration of national defense and civilian development, China has independently developed the Compass Navigation Satellite System, which made it the third country with autonomous Navigation Satellite System after the United State and Russia. The independent operation of Compass Navigation Satellite System ensures the security and stability of the country and will also promote the development of a number of civil industries. Cooperative localization with other navigation satellite systems is especially important to improve civil application and ensure the consecutiveness and accuracy of navigation service. Based on the opportunity of China publicly releasing the ICD (Interface Control Document) of Compass Navigation Satellite System in2012, this paper researched the algorithms using for positioning solution and the realization technology of navigation receiver in case of GPS/BD dual-mode. The research results about GPS/BD dual-mode GNSS receiver were applied in the software part of GPS/BD dual-mode baseband chip. The following aspects are included in this paper:(1) By researching on the ICD of Compass Navigation Satellite System in detail, this paper analyzes the similarity and difference between GPS and Compass, including space constellation, signal waveband, time system and space coordinates system. Firstly, each sub-module of positioning solution about Compass Navigation Satellite Single-mode System is realized by software, especially differentiating the GEO and Non-GEO satellites of Compass. Then the difficulty of cooperative localization of GPS/BD dual-mode system is discussed as well as the way to solve it. And the principle and realization of dual-mode positioning solution is discussed, including the corresponding unified module of dual-mode time system and space coordinates system.(2) In the study of dual-mode positioning solution technologies, this paper discusses the dual-mode satellite selection algorithm, the dual-mode consistency check methods of satellites and the realization of dual-mode kalman filtering. Firstly, A multi-mode satellite selection algorithm based on optimal geometry is proposed, which could reduce the computation burden without too much loss of performance. Secondly, unlike the traditional top-down consistency check method, this paper discusses the new bottom-up method aiming at dealing with environments with strong multipath effect, which is proved to be more stable in the simulations of multipath environments. Besides, the dual-mode serial calculation and corresponding innovation check of kalman filtering is studied and implemented, making the dual-mode localization results to be more smooth and continuous.(3) Based on the construction of GNSS receiver hardware platform, the software framework of positioning solution part of GPS/BD dual-mode receiver baseband chip is designed, unifying the relevant GPS and Compass software sub-modules. And the total process of dual-mode positioning solution is displayed clearly and completed by software. The road-testing of GPS/BD dual-mode receiver performs properly, and the localization performance is tested as well.