【作者】 姜毅；

【导师】 张淑芳；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2010， 博士

【摘要】 目前,国内很多高校和研究院所都致力于自主知识产权高性能GNSS接收机的研究工作,并取得了丰硕的研究成果,为我国实现GNSS接收机芯片市场的国产化做出了积极的努力。数字基带信号处理是GNSS接收机设计的核心,对接收机的性能具有至关重要的作用。本文主要对如何在数字基带信号处理部分提高GNSS接收机性能,减少接收机占用资源,提高接收机性价比方面开展研究,对GNSS接收机高性能跟踪和捕获环路算法进行深入的探讨,主要包括以下几个方面：首先,针对多径信号环境下GNSS接收机的码延迟锁定环路的定位精度会受到严重影响的问题,分别在多径信号非衰落和衰落的条件下,研究各种码延迟锁定环路算法的抗多径性能,对环路的跟踪误差特性进行定量的分析与比较。并在此基础上,给出不同多径信号条件下的最优码延迟锁定环路算法。其次,针对GPS接收机中载波跟踪环路鉴别器算法复杂度高的问题,提出一种基于四象限反正切函数的环路鉴别器算法。利用校正函数使鉴相器对导航电文数据翻转不敏感,使鉴频器克服频率调整模糊度；且鉴相器和鉴频器仅需一个共用的四象限反正切运算单元。通过理论分析和仿真实验,证实该鉴别器算法具有运算量小,复杂度低的特点,能够减少环路鉴别器所用的接收机资源。然后,针对GPS接收机载波跟踪环路滤波器算法实现复杂的问题,提出一种基于矩形波数字积分器的锁频环辅助锁相环的环路滤波器算法。并在上述研究的基础上,给出一种低复杂度的GPS载波跟踪环路设计方案。通过理论分析与仿真实验证实,该载波跟踪环路可以减小实现复杂度,提高运算速度,并对GPS载波信号具有良好的动态跟踪性能。最后,针对GPS接收机频域捕获算法运算量大的问题,提出一种改进的平均圆周相关捕获算法,并给出具体实现方法。该算法利用对中频信号的二次采样和复数信号频谱的不对称特性,达到减小频域捕获算法运算量的目的。实验结果表明,该捕获算法在不降低捕获精度的前提下,使GPS接收机具有快速的捕获能力,且更易于实现。综上所述,本文提出的提高GNSS接收机跟踪和捕获环路性能的算法,在理论研究的基础上,利用模拟的和实际的GPS信号进行了实验,并取得了预期的效果,对于设计高性能和高性价比的接收机具有重要的理论价值和实际参考意义。更多还原

【Abstract】 In China, many universities and research centers have been devoted to the design of a high performance GNSS receiver with independent intellectual property rights and represented very great achievements at present. It contributes to an increasing marketization of domestic GNSS receiver chips. Digital baseband signal processing is the key topic in the design for a GNSS receiver. It has a great influence on the receiver performance. In this thesis, tracking and acquisition loop algorithms in digital baseband signal processing for a GNSS receiver are investigated. It is helpful to improving the receiver performance, reducing resources in the design of GNSS receivers and enhancing cost performance of domestic GNSS receivers. The main contributions of this thesis are summarized as follows:Firstly, the positioning accuracy of a delay-locked loop in a GNSS receiver is seriously affected by multipath. Multipath effects on common DLLs are approached by comparisons under non-fading and fading conditions. Furthermore, the characteristics of tracking errors induced by multipath in DLL discriminators are evaluated and analyzed. A proper DLL for the specialized multipath environment is given.Secondly, in order to reduce discriminator complexity of carrier tracking loops in a GPS receiver, an improved discriminator algorithm based on the four-quadrant arctangent function is proposed. The phase and frequency discriminators share only one four-quadrant arctangent function. A phase discriminator is insensitive to the navigation message data and a frequency discriminator overcomes the frequency uncertainty by correction functions. Through theoretical analysis and simulation, the proposed discriminator algorithm with a small calculation amount and low complexity is validated. Therefore, carrier tracking loops occupy less system resources.Thirdly, a loop filter structure affects the complexity of a GPS carrier tracking loop critically. A novel loop filter design based on a boxcar digital integrator is given. On this basis, a low complexity design for a GPS carrier tracking loop is represented. The theoretical analysis and simulation results confirm that this novel design not only has low complexity, but also exhibits excellent dynamic tracking performance. Finally, in view of the calculation amount of acquisition algorithms in frequency domain, a new modified averaging circular correlation algorithm based on FFT is proposed and its implementation method is described. This novel algorithm reduces calculation amount in frequency domain by making use of the second sampling and spectrum asymmetry. Simulation results show that it has faster acquisition ability and is easy to be realized without a deleterious effect on the acquisition accuracy.Therefore, the proposed algorithms to improve the performance of GNSS receivers in this thesis are based on theoretical investigation and experiments with the simulated and real GPS signals, and then show expectable results. It has a great theoretical and practical significance on the design of high performance and cost performance receivers.更多还原