低复杂度的北斗定位捕获跟踪技术研究

发布时间：2019-01-22 10:40

【摘要】：北斗卫星导航定位系统(BDS)作为我国正在研发并建设的具有自主知识产权的全球卫星导航定位系统,对我国甚至全世界的相关应用领域产生了巨大的价值。而随着卫星导航应用需求的增长以及快速定位的要求,北斗信号的捕获跟踪复杂度成为了卫星接收机的一个重点研究方向。当前在北斗卫星捕获跟踪阶段通常采用基于离散傅里叶变换的并行码相位的捕获算法来进行捕获。相较于时域串行捕获,算法能大大缩短捕获的时间,但对接收机硬件资源的要求较高。为了快速定位以及减少卫星接收机的硬件资源消耗,我们需要寻找算法复杂度更低的算法来进行捕获跟踪从而达到这一目的。本文针对卫星定位捕获跟踪算法复杂度高,运算量大的问题,从如下方面展开了研究:第一,介绍了北斗卫星信号的结构,分析了常用的捕获跟踪方法和步骤,对采用基于离散傅里叶变换的并行码相位的捕获算法做了仿真,成功对信号进行了捕获跟踪。第二,在采用并行码相位捕获的基础上,通过平均相关的办法,将信号的采样点数变为2的整数次幂,从而变DFT为FFT,大大的减少运算量。提出了一种本地码二次采样法,在做平均相关的降低运算量的同时,获得更优的性能。本文对这种方法进行了仿真,成功捕获到了信号,并和基于离散傅里叶变换的并行码相位的捕获算法从性能和运算量上进行了对比。第三,通过对卫星信号结构的分析,利用卫星导航信号的稀疏性,引入了提出不久的稀疏傅里叶变换,根据卫星信号特点对其作了部分修改,提出了一种简化的基于稀疏傅里叶变换的捕获方法,在损失部分性能的情况下,减少了算法的运算复杂度。本文对这种方法进行了仿真,成功捕获到了信号,并与之前基于采用改进的平均相关的捕获算法从性能和运算量上进行了对比。第四,引入了地面差分站,讨论地面差分站辅助数据对整个捕获跟踪阶段算法复杂度的影响。通过对辅助数据的计算可以求得多普勒频移的预估值和频率误差值和码片相位的范围,降低了频率搜索范围,将其带入基于稀疏傅里叶变换的捕获算法中,改进了上文提到的稀疏傅里叶变换的复杂度,降低了整个算法的运算量。在接收机设计与实现的过程中,采用低复杂度的捕获跟踪算法能够降低硬件资源的开销,实现信号的快速及可靠捕获跟踪,从而达到各行业对捕获跟踪快速准确的捕获跟踪要求。
[Abstract]:Beidou Satellite Navigation and Positioning system (BDS) is a global navigation and positioning system with independent intellectual property rights which is being developed and built in China. With the increasing demand of satellite navigation application and the requirement of fast positioning, the acquisition and tracking complexity of Beidou signal has become an important research direction of satellite receiver. At present, in the phase of Beidou satellite acquisition and tracking, a parallel code phase acquisition algorithm based on discrete Fourier transform (DFT) is usually used to capture. Compared with the time domain serial acquisition, the algorithm can greatly shorten the acquisition time, but the receiver hardware resource requirements are higher. In order to quickly locate and reduce the hardware resource consumption of satellite receiver, we need to find a less complex algorithm to capture and track to achieve this goal. In order to solve the problem of high complexity and large computational complexity of satellite positioning acquisition and tracking algorithm, this paper studies the following aspects: firstly, the structure of Beidou satellite signal is introduced, and the commonly used acquisition and tracking methods and steps are analyzed. The parallel code phase acquisition algorithm based on discrete Fourier transform (DFT) is simulated and the signal is successfully captured and tracked. Secondly, on the basis of the parallel code phase acquisition, the sampling point of the signal is changed to the integer power of 2 by the method of average correlation, thus changing DFT to FFT, greatly reduces the computation. In this paper, a local code quadratic sampling method is proposed, which can achieve better performance while reducing the computational complexity of average correlation. In this paper, the method is simulated, and the signal is successfully captured, and compared with the parallel code phase acquisition algorithm based on discrete Fourier transform (DFT) in terms of performance and computational complexity. Thirdly, by analyzing the structure of satellite signal and utilizing the sparsity of satellite navigation signal, a new sparse Fourier transform is introduced, which is partly modified according to the characteristics of satellite signal. A simplified acquisition method based on sparse Fourier transform is proposed, which reduces the computational complexity of the algorithm without partial performance loss. In this paper, the method is simulated, and the signal is successfully captured, and compared with the previous average correlation acquisition algorithm based on the improved average correlation in terms of performance and computational complexity. Fourthly, the ground differential station is introduced to discuss the influence of the auxiliary data of the ground difference substation on the complexity of the algorithm in the whole acquisition and tracking stage. Through the calculation of the auxiliary data, we can get the Doppler frequency shift preestimate and the range of frequency error and chip phase, reduce the frequency search range, and bring it into the acquisition algorithm based on sparse Fourier transform. The complexity of the sparse Fourier transform mentioned above is improved, and the computational complexity of the algorithm is reduced. In the process of designing and implementing the receiver, the low complexity acquisition and tracking algorithm can reduce the cost of hardware resources and realize the fast and reliable acquisition and tracking of signal. In order to achieve the industry to capture tracking fast and accurate capture and tracking requirements.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN967.1

【相似文献】