【作者】 狄旻珉；

【导师】 张尔扬；

【作者基本信息】 国防科学技术大学 ， 信息与通信工程， 2006， 博士

【摘要】 本文主要对天线与GPS接收机之间的抗干扰单元及其关键技术进行研究。由于卫星导航定位系统的广泛使用,使得对其抗干扰技术的研究显得迫在眉睫。论文就针对GPS系统的抗干扰技术进行研究。传统的GPS抗干扰接收技术存在抗干扰效果差、每种技术只能对有限几种干扰进行抑制的问题。所以,空时处理的方法就体现出了优势。空时处理可以抑制多种干扰,并且由于抗干扰处理的自由度大大增加,抗干扰能力也有大的提高。然而,空时处理在提高抗干扰能力的同时也会使计算量显著增加。因此,为了降低计算量,就需要研究降维的算法。针对常用的多级维纳滤波(MWF)降维算法,为了进一步降低运算量,论文第二章给出了对MWF前向递推的算法过程进行简化的方法。仿真结果证实了其性能。多径效应是除干扰外GPS系统最主要的误差源之一,传统的CDMA抑制多径效应的方法不能应用于GPS系统。通用的GPS多径效应抑制技术受限于物理环境和电磁环境。基于此,论文第三章针对不同的电磁环境、不同接收机的要求,给出了两种GPS多径效应抑制的方法并给出了仿真结果。由于干扰和多径效应都会对GPS接收产生严重影响,所以研究多径效应存在时的GPS抗干扰接收就十分重要。论文第四章给出了两种接收机的设计方案。一种具有较小的复杂度和运算量,适用于电磁环境变化的情况,但性能稍差。另一种复杂度较高,适用于电磁环境慢变或不变的情况,性能较好。两种方法均通过了仿真验证。现代的电磁环境中存在多种电子设备,所以就需要解决不同电子系统间的兼容问题,论文第五章研究了GPS系统与窄带数字系统、宽带CDMA系统和UWB系统的兼容问题,给出了抑制这些电子系统对GPS系统影响的方法。同时给出了一种抑制GPS系统多址干扰的方法,并通过仿真验证其性能。由于环境或器件工艺的原因,会引起接收机在接收信号时产生同步时钟抖动,从而引起系统误码率的恶化。因此论文第六章通过理论推导与分析,给出了抖动对GPS系统性能影响的数学结果,并对此进行仿真,仿真结果对实际工程应用有一定的参考价值。更多还原

【Abstract】 The paper focused on the key technologies of the anti-jamming unit between antennas and GPS receiver.Since satellite navigation systems have already been used widely, the ways to improve their anti-jamming capability become an emergent task. The paper majors in anti-jamming technologies of GPS. The traditional technologies are not as good as enough because each of them can only treats limited kinds of interferences. Space-Time adaptive processing technology (STAP) shows great predominance in interferences elimination. Almost all kinds of interferences can be counteracted by STAP technology. Since the degrees of freedom in anti-jamming capability are increased, STAP technology performs a very important role in GPS interferences elimination. However, the computational burden of STAP increases enormously along with the improvement of anti-jamming capability. To deal with the problem, a reduced-rank algorithm is needed. In the dissertation, a simplified multistage nested wiener filter (MWF) was presented in chapter 2. The simplification on forward recursion of MWF was implemented. As a consequence, the cost on computation decreased greatly. The results of simulations certified it.Multipath effect is another major source of GPS error besides interferences. The usual ways used in CDMA systems can not be utilized in GPS systems. The technologies employed in GPS are also restricted by physical and electromagenetic circumstances. The dissertation presents two different ways to deal with the multipath effect in chapter 3. Each of them was designed for one specific situation. Finally, the simulation results were presented.Since the interferences and multipath effect both can deteriorate the performance of GPS receivers, it is crucial to study the anti-jamming technology under the circumstances with multipath effect. The dissertation showed two designs of GPS receivers in chapter 4. One of them was of low complexity and designed for the condition that the electromagnetic circumstance changing fast. The other was of higher complexity and designed for the condition that the electromagnetic circumstance that never chang or change slowly. Its performance was comparatively better than the former. Both methods were proved by the simulations.Nowadays, an electronic facility can not be used alone. There are many kinds of them are active in the same time. The coexistence of GPS with other digital systems needs more attention then. The dissertation analyzed the problems of GPS receivers caused by narrowband digital systems、wideband CDMA systems and UWB (Ultra-Wide Band) systems, which leads to the conclusion that MUD (Multiuser Detection) was an efficient way to solve the coexistence of these systems. Additionally, a way to eliminate MAI in GPS systems was discussed in chapter 5. Its capability was proved by the simulation results.During the reception of GPS signals, the jitter of clock is caused by the electromagnetic circumstance or the bad performances of electronic elements. As a result, the BER of the systems deteriorate greatly. The dissertation analyzed the effect of jitter theoretically and presented a mathematical expression of the effect in chapter 6. Also simulation results were shown. The results can be useful for technical utilization.更多还原