【作者】 张晶泊；

【导师】 张淑芳；

【作者基本信息】 大连海事大学 ， 通信与信息系统， 2012， 博士

【摘要】 拥有全球导航卫星系统(GNSS)是航天大国的重要特征,它的发展不仅代表着一个国家的科技水平,同时会给该国带来巨大的军事和经济利益。中国北斗卫星导航系统已经于2011年12月27日宣布具备初步运行能力,从而拉开了该系统从建设到应用的序幕,使GNSS接收机技术研究领域得到了难得的发展机遇,国家制定了一系列的政策和措施,用以鼓励具有自主知识产权的相关核心技术的研究。为了提高GNSS接收机的性能,国内外的科研人员在多个不同的方向进行了深入研究,本文的选题是高动态载波跟踪环路关键技术。高动态主要是指接收机载体具有较高的速度和加速度。在高动态的环境下,由于多普勒效应的影响,使接收机获得的载波产生较快速的频移,这将影响载波跟踪环路的稳定性,特别是当载波的频移速度超过环路的动态范围时,接收机将无法正常工作。由于高动态接收机主要用于军事、航空等高端领域,西方发达国家对我国在相关技术上实施封锁和限制,很多研究成果属于技术保密范畴。所以我国鼓励在该领域进行深入研究,因此本文的研究具有理论和实际意义。本文的研究工作主要包括以下几个方面：(1)为了对载波跟踪环路的动态范围进行定量的描述,提出了有效工作带宽这个概念,并发现了在GNSS软件接收机中,载波环路的有效带宽存在理论上界,并得到了该理论上界的数学公式模型。该发现为确定高动态环境下载波跟踪环路允许的最大多普勒频移变化率提供了理论依据。(2)为了提升载波环路对于多普勒频偏的跟踪速度,提出了一种基于自适应增益控制理论的载波环路设计方案,并给出了相应的自适应控制算法的数学模型。通过仿真实验证实,该方案对于不同幅度的多普勒频偏均能实现最优调节,提升了载波环路对于多普勒频移的响应速度,从而提高了传统载波环路的高动态跟踪性能。(3)为了提高载波环路对于多普勒频偏的预测能力,提出了一种基于短时循环迭代方式的多普勒参数检测算法,并给出了基于此算法的全新载波跟踪环路设计方案。通过仿真实验证实,该算法仅需要少量相位误差测量值和经典频域数字滤波器就能够估计出载波多普勒频偏的高阶变化率,使得环路具备了对载波多普勒频移的短时预测能力,实现了高动态环境下的载波跟踪。(4)为了在提高载波环路动态性能的同时尽可能的减少噪声干扰,提高环路的跟踪精度,提出了一种自适应卡尔曼滤波算法,并引入了多普勒参数检测算法对传统的卡尔曼滤波器进行优化,同时利用模糊控制理论对系统的观测噪声矩阵进行自适应调节。通过仿真实验证实,该算法在实现多普勒参数检测的基础上,对随机噪声序列实现了最优滤波,提升了多普勒频偏各阶变化率的估计精度,从而提高了高动态环境下载波环路的跟踪性能。上述研究内容在理论研究和方案设计的基础上,利用Spirent GSS8000模拟器和实际的GNSS信号,构建了软件接收机开发平台,并进行了实验验证,取得了比较理想的成果,为开发具有高动态性能的GNSS软件接收机奠定了理论和技术基础。更多还原

【Abstract】 Global Navigation Satellite System(GNSS) is a symbol of space powers, which represents the technological and scientific level and brings tremendous military and economic benefits. The Chinese BeiDou satellite navigation system was announced to be able to initially operate in 27th Dec.2011. The application of the Beidou system brings an important development chance to the research on GNSS receiver. China has carried out a series of incentive policies and measures to encourage the research on relative core technology with independent intellectual property.In order to improve the performance of GNSS receiver, researches have been done in various directions. The paper focuses on the key technology of high-dynamic carrier tracking loop. High-dynamic mainly refers that the receiver has higher velocity and acceleration. In the high-dynamic environment Doppler shift makes the carrier generate large shift, which affects the stability of the carrier tracking loop. Especially when the carrier velocity exceeds the dynamic range of the loop, the receiver cannot work normally.As the high-dynamic receiver is mainly used in the high-end field such as military and space, and the western developed countries restrict on exporting the relative technology to China, lots of research results are remain confidential. Now, China is encouraging the deep research in this field. Therefore, the paper has both theoretical and practical applications.The research consists of the following aspects:(1) We propose the concept of effective operating bandwidth in order to measurably describe the dynamic range of carrier tracking loop. And we find the theoretical upper bound of the effective operating bandwidth in the loop and give the mathematical model of the upper bound. This discovery provides theoretical basis for the allowable maximum Doppler shift transition in the high-dynamic environment.(2) In order to raise the velocity of tracking Doppler shift in the loop, we propose a carrier loop design based on the theory of self-adaptive gain control and we give the corresponding self-adaptive control algorithm. The simulation results prove that the design can maximumly optimize the Doppler shift in different extent, which raise the response speed of the loop. Thus the high-dynamic tracking performance of the loop can be enhanced.(3) We put forward a novel Doppler-Parameter detection algorithm based on short-term iteration and give a new tracking loop design based on the algorithm so as to improve the capability of estimating Doppler shift. The simulation results show that only a few phase error measurements and a classical frequency digital filter are required to estimate the high-order transitions of Doppler shift. As a result, the loop is capable of estimating the short term of the Doppler shift, which achieves tracking carrier in the high-dynamic environment.(4) We give a self-adaptive Kalman filter algorithm by introducing Doppler-Parameter detection algorithm to optimize the traditional Kalman filter and using fuzzy control to self-adaptive adjust the observed noise matrix. It can improve the tracking accuracy and reduce the noise while enhancing the high-dynamic performance. The simulation results prove that the algorithm can optimize the filter for the random noise series and improve the estimation accuracy for each order transition of Doppler shift. Therefore, the tracking performance of the carrier loop in the high-dynamic environment can be improved.Based on the above theoretical research and design, we adopt Spirent GSS8000 simulator and practical GNSS signal to build the software receiver platform. Through a lot of simulation experiments, we get ideal results. This research in this paper provides a theoretical and technical basis for the development of GNSS software receiver with high-dynamic performance.更多还原