导航信号预失真算法设计及评估

发布时间：2018-06-21 16:09

本文选题：全球导航卫星系统 + 信号质量　；参考：《华中科技大学》2014年硕士论文

【摘要】：全球导航卫星系统（GNSS）通过在轨卫星发射无线电信号提供无源定位服务，导航信号的质量对于系统的性能指标至关重要。由于星上载荷核心器件的非理想特性，实际发射的导航信号是理想信号经历了一系列线性失真和非线性失真的产物，相比于传统的GPS导航信号，新型导航信号由于带宽更大受到的影响更为显著。导航信号的失真可能导致系统定位精度和准度下降甚至无法定位，因此对信号发射通道的失真特性进行补偿具有重要的意义。为改善星上发射通道的非理想特性对信号质量的恶化，本文研究了通过导航信号的预失真实现信道补偿的算法，并对预失真的性能进行了评估，开展的具体工作包括以下内容：研究卫星导航信号一般模型及其接收原理，分析信号失真对接收性能的影响；介绍用于导航信号质量评估的有关指标，并分析以上指标与接收机性能的关系；对星上载荷核心器件进行建模，包括无记忆高功放、有记忆高功放、滤波器，分析它们对导航信号质量的影响；提出针对无记忆高功放的查找表预失真算法，包括离线学习和在线学习两套方案，并仿真验证它们的线性化效果；提出针对有记忆高功放的预失真算法，包括基于间接学习结构的记忆多项式法以及滤波器查找表级联法；提出针对滤波器的预失真方法，并仿真验证它对频率响应的改善；仿真验证针对各单独非理想器件以及整体发射通道的预失真算法对导航信号质量的影响。本文的研究表明星上滤波器的群时延波动会对导航信号的定位准度造成严重影响，高功放的非线性特性会导致带外谱再生，此外二者都会带来定位精度以及解调性能的下降。信号预失真对信道失真特性的补偿可转化为导航信号质量指标的全方位显著提升，并最终体现为导航系统服务性能的提升。
[Abstract]:GNSS (Global Navigation Satellite system) provides passive positioning service by transmitting radio signals from satellites in orbit. The quality of navigation signals is very important to the performance of the system. Because of the non-ideal characteristics of onboard payload core devices, the actual transmitted navigation signal is the result of a series of linear and nonlinear distortion of the ideal signal, compared with the traditional GPS navigation signal. The new navigation signal is affected more obviously because of the larger bandwidth. The distortion of navigation signal may cause the positioning accuracy and accuracy of the system to decrease or even be unable to locate, so it is of great significance to compensate the distortion characteristics of the signal transmission channel. In order to improve the deterioration of signal quality due to the non-ideal characteristics of onboard transmission channel, a channel compensation algorithm based on pre-distortion of navigation signal is studied in this paper, and the performance of pre-distortion is evaluated. The specific work carried out includes the following contents: research on the general model of satellite navigation signal and its receiving principle, analysis of the influence of signal distortion on reception performance, and introduction of relevant indicators used to evaluate the quality of navigation signal, The relationship between the above indexes and the receiver performance is analyzed, the core components of onboard load are modeled, including memoryless high power amplifier, memory high power amplifier, filter, and their influence on navigation signal quality are analyzed. This paper proposes a look-up table predistortion algorithm for memoryless high power amplifier, including offline learning and online learning, and simulates their linearization effect, and proposes a predistortion algorithm for memory high power amplifier. It includes the memory polynomial method based on indirect learning structure and the filter lookup table cascade method, and proposes a predistortion method for the filter, and simulates the improvement of its frequency response. Simulation results show that the predistortion algorithm for individual non-ideal devices and the whole transmission channel affects the quality of navigation signal. The research in this paper shows that the group delay fluctuation of the onboard filter will seriously affect the positioning accuracy of the navigation signal, and the nonlinear characteristics of the high power amplifier will lead to the regeneration of the out-of-band spectrum. In addition, both of them will bring about the degradation of the positioning accuracy and demodulation performance. The compensation of signal predistortion to channel distortion can be transformed into a significant improvement of navigation signal quality, and finally the improvement of navigation system service performance.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN96.1

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