【作者】 付晓；

【导师】 赵雅琴；

【作者基本信息】 哈尔滨工业大学 ， 信息与通信工程， 2010， 硕士

【摘要】 伪码测距是目前航天测控系统、跟踪与数据中继卫星系统和全球导航定位卫星系统中普遍采用的测距方法。与其他测距方法相比,伪码测距具有信号功率谱密度低、对邻近信道干扰小、保密性强难以被截获、可以实现码分多址等优势。同样,与其他测距方法一样,伪码测距方法亦会受到各种误差源的影响而产生测距误差。伪码测距方法中的系统误差可以通过一定的模型或数据处理方法消除其影响,而由信道环境中的偶然因素,如射频干扰源、多径效应等,造成的随机误差则难以模拟或消除。伪码测距精度由系统选择的伪码码元宽度和接收机的跟踪精度共同决定。码元宽度的限制可以通过调整伪码时钟来解决,而接收机的跟踪精度除了受到本身硬件结构的限制,更容易受到外界环境中的各种干扰的影响。论文首先介绍了伪码测距系统的基本组成和测距原理,以及伪码测距接收机中伪码跟踪环和载波跟踪环的工作原理;论述了利用载波跟踪环的载波相位测量值辅助伪码延时估计的载波辅助技术及实现;然后研究了射频干扰环境中射频干扰源对伪码测距接收机环路载噪比的影响,进而分析了其对信号捕获和跟踪的影响,并给出了其对测码和测相伪距测量误差影响的仿真结果;最后在详细分析多径信号特点的基础上,给出了多径干扰环境下多径信号的误差模型,分析了多径干扰下的码跟踪环性能,并仿真了在低反射和高反射环境下多径信号相对相位延迟和相对幅度的变化对伪距测量误差的影响;同时,分析并仿真了两种反射环境下,多径干扰引入的载波相位误差。更多还原

【Abstract】 PN code ranging method is widely used in the TT & C system, Tracking and Data Relay Satellite System and Global Navigation Satellite System. Compared with the other ranging methods, PN code ranging signal has advantages such as, low power spectral density, small interference on adjacent channel, strong confidentiality, being difficult to be intercepted, applying in CDMA system. In the same way as other ranging methods, PN code ranging is also affected by various error sources. The systematic errors can be eliminated by modeling or data processing method, however, ranging random errors caused by accidental environment factors are difficult to be modeled or eliminated.The accuracy of PN code ranging is codetermined by selected PN code element width and receiver’s tracking accuracy. The limitation by symbol width can be solved by adjusting the clock frequency. In addition to hardware limitations, the tracking accuracy is vulnerably affected by external environment interferences.This dissertation first introduces the structure of PN ranging system and basic principles of PN code ranging as well as code tracking loop and carrier tracking loop working in PN code ranging receiver. The usage of the estimation of the carrier phase estimated by carrier tracking loop is being investigated. By making use of the carrier-assisted technology, such that we can obtain the accurate pseudo-code delay estimation. After the analysis of the changes of loop carrier to noise power ratio under RF interference environment, the simulation results of pseudo-range measurement error of are presented. Finally, this dissertation presents careful analysis of the characteristics of the multipath signals, under high and low refraction environment, the pseudo-range errors and carrier-phase tracking errors which introduced by the mutlipath effect are thoroughly investigated, and then the simulation results are presented.更多还原