【作者】 孙晓文；

【导师】 张淑芳；

【作者基本信息】 大连海事大学 ， 信息与通信工程， 2012， 博士

【摘要】 随着全球导航卫星系统(GNSS, Global Navigation Satellite System)的发展和接收机性能的不断提高,卫星导航系统越来越广泛地应用于各个领域。我国也在积极发展自己的北斗卫星导航系统,但是,由于缺乏接收机技术的积累,高性能接收机核心技术已经越来越成为我国导航产业链的瓶颈。因此,提高导航接收机性能的研究,已经成为当前重要而且紧迫的任务。本文在GNSS接收机方面进行了深入的研究,提出了一种名为MRake (Modified Rake)的抗多径的新结构,并深入研究该结构对接收机各主要环节性能的影响,在提高接收机抗多径性能,捕获速度,跟踪灵敏度以及定位解算精度等方面取得了一定的成果,为我国研究高性能接收机技术提供理论和实践参考。本文的研究工作主要包括以下几个方面：首先,针对现有抗多径技术性能和资源消耗之间的矛盾,利用MRake结构来减少GPS接收机中的多径误差。它能够对接收信号中的直达和多径成分分别进行跟踪,并用直达成分的传播延时来计算用户位置。MRake结构不仅具有良好的抗多径性能,而且无需大量的硬件资源或复杂的运算。其次,根据MRake结构能够对直达和多径信号分别跟踪的结构设计特点,它在快速有效捕获信号方面也能够发挥重要作用。因此,采用伪码并行载波串行的时域搜索方法,从而充分地利用了MRake结构的硬件资源,提高捕获速度；在此基础上,进一步采用扩展的多相关器方法,在不增加硬件资源的前提下,进一步提高捕获速度；将捕获到的卫星信号看作直达信号,再利用MRake结构有效地捕获和分离出多径信号。然后,为了满足人们对室内等复杂环境中导航定位的需求,深入研究了提高接收机跟踪灵敏度的技术。在对常用技术进行定量分析,并总结其不足的基础上,提出了一种改进的经典Costas (MCC, Modified Classic Costas)鉴相器算法,它对经典Costas (CC, Classic Costas)鉴相器进行改进,在不增加运算量的情况下,大幅地提高接收机的跟踪灵敏度。最后,针对定位解算算法中最常用的最小二乘法和卡尔曼滤波方法的不足,提出了两种定位解算的新算法。其中,改进的卡尔曼滤波(MKF, Modified Kalman Filtering)算法在提高定位解算精度的同时,避免了对噪声协方差阵的复杂运算；粒子滤波(PF, Particle Filtering)算法进一步提高了定位解算精度,并克服了传统卡尔曼滤波定位算法需要预知载体运动模型和噪声特性的缺点。在对上述内容进行理论研究和方案设计的基础上,利用Spirent公司的模拟器产生GPS信号对其进行了实验验证,并取得了预期的效果,研究成果对设计高性能的导航接收机具有重要的实用价值和参考意义。更多还原

【Abstract】 The GNSS (Global Navigation Satellite System) system is more and more widely used in various fields with the development of the system and continuous improvement of the receiver’s performance. China is also actively developing its own Beidou satellite navigation system. However, due to the lack of receiver technology accumulation, the core technology of high performance receiver has increasingly become the bottleneck of the navigation industry chain in China. Therefore, improving the performance of navigation receiver has become an important and urgent task. This thesis researches in-depth on GNSS receiver. It proposes a new anti-multipath architecture named MRake (Modified Rake), and researches in-depth on the impact of MRake architecture on performance of the receiver’s main aspects. It has made certain achievements in improving the anti-multipath performance, acquisition speed, tracking sensitivity and position calculation precision. The achievements provide a theoretical and practical guidance for high performance receiver research in China. The main contributions of this thesis are summarized as follows:First, to solve the conflict between the performance and resource consumption of existing anti-multipath techniques, MRake architecture is used to reduce the multipath error in GPS receiver. It tracks direct-path and multipath components of the received signal separately, and uses the time-delay of direct-path component to calculate the user’s position. The proposed MRake structure has good anti-multipath performance without consumption of many hardware resources or complex calculation.Secondly, since MRake architecture can track the direct and multipath signals separately, it also can play an important role in capturing signals quickly and efficiently. Using the parallel pseudo-code searching and serial carrier searching method in time domain can make full use of hareware resources in MRake structure to improve the acquisition speed. On this basis, use extended multiple correlator (XMC) method to further improve the acquisition speed without increasing the hardware resources. Treat the acquired satellite signal as direct-path signal, and then capture and separate the multipath signals by MRake structure. Thirdly, in order to meet the demand of navigation in complex environments such as indoor environment, the technology to improve the tracking sensitivity of the receiver is studied in depth. Based on the quantitative analysis of the common techniques and summarization of their problems, an MCC (Modified the Classic of Costas) phase detector algorithm is proposed. It modifies the CC (Classic Costas) phase detector, and can significantly improve the tracking sensitivity without increaseing the calculation.Finally, to solve the problems of two most commonly used position calculation algorithms, least square method and Kalman filtering method, two new algorithms are proposed. One is MKF (Modified Kalman Filtering) that can improve the positioning accuracy and avoid the complexity calculation of the noise covariance matrix. Another one is PF (Particle Filtering) that can further improve the positioning accuracy, and overcome the drawbacks of traditional Kalman filter that requires prior knowledge of receiver’s dynamic model and noise properties.Based on the above theoretical study and program design, experiments with GPS signals generated by Spirent simulator have achieved the anticipated results. The research has important practical value and referential significance on the high performance navigation receiver design.更多还原