基于波束控制的卫星导航接收机抗干扰算法研究

卫星导航接收机抗干扰技术是接收机设计的一项关键技术。在研究基于功率反演的空域自适应抗干扰算法基础上,提出了采用基于波束控制的抗干扰算法,并进行了仿真计算,结果表明：该算法明显提高了接收机抗干扰性能。     

地磁匹配导航算法研究

提出一种MonteCarlo方法和均方差算法（MSD）相结合的匹配算法,并将本算法用于地磁匹配导航中。该方法根据惯性导航系统指示的位置从地磁图上提取参考地磁数据,将地磁测量数据进行若干次随机干扰后和参考地磁数据使用MSD算法进行匹配,得到若干个匹配位置,取其均值作为最终匹配位置。仿真结果表明本算法可行。     

GPS车载导航的交互式多模型算法

GPS动态定位数据的处理广泛采用卡尔曼滤波技术,而应用卡尔曼滤波要求运动模型准确可靠,但由于载体真实运动的复杂多变,任何单一模型都难以全面描述,致使单一模型的滤波都容易出现模型误差。针对这一问题,将机动目标跟踪领域广泛应用的交互式多模型算法引入到车载导航中。通过分析车辆的运动特点,选取匀速直线模型和当前统计模型进行交互;同时考虑到车载终端计算能力有限,将状态变量在各方向解耦。仿真显示,在机动时改进的算法和单一模型的自适应算法基本相当,但在非机动时改进的算法明显占优。     

BOC调制信号多径误差分析

针对导航信号的多径误差分析,在多径误差包络曲线分析方法基础上提出了多径误差包络期望分析方法。与包络曲线分析方法相比,包络期望分析方法能够定量分析导航信号多径误差。基于包络期望分析方法,对同码速率的二进制偏移载波(BOC)调制导航信号与二进制相位控键(BPSK)调制导航信号的多径误差进行了对比分析。结果表明,BOC调制导航信号具有更小的典型多径误差。     

On exact solutions of the multi-constellation GNSS navigation problem

In Global Navigation Satellite System (GNSS) positioning, the receiver measures the pseudorange with respect to each observable navigation satellite and determines the position and clock bias. In addition to the GPS, several other navigation satellite constellations including Glonass, Galileo and Compass can/will also be used to provide positioning, navigation, and timing information. The paper is concerned with the solvability of the navigation problem when the receiver attempts to process measurements from different constellations. As two different constellations may not be time-synchronized, the navigation problem involves the determination of position of the receiver and clock bias with respect to each constellation. The paper describes an analytic approach to account for the two-constellation navigation problem with three measurements from one constellation and two measurements from another constellation. It is shown that the two-constellation GNSS navigation problem becomes the solving of a set of two simultaneous quadratic equations or, equivalently, a quartic equation. Furthermore, the zero-crossover of the leading coefficient and the sign of the discriminant of the quartic equation are shown to play a significant role in governing the solvability, i.e., the existence and uniqueness of the navigation solutions.

基于Multisim X的计算机辅助电子电路设计

学好<电子线路>这门课程,不仪需要有扎实的电路分析和信号与系统等专业基础知识,还需要在学习过程中加入单元或系统电路的实验环节,这样才能完成整个电路的设计.介绍如何在电路的理论没计基础之上,以Multisim X这一仿真软件为实验平台,仿照硬件环境来完成电路的最终设计的.     

北斗三星无源导航定位技术研究

简述北斗三星无源导航定位的原理及定位误差源。探讨用最优估计理论和方法,即卡尔曼滤波技术,消除北斗三星无源定位数据中随机误差的方法。对华南沿海北斗三星无源定位实验数据进行滤波处理,结果表明:(1)北斗三星无源定位单点定位精度在纬度方向为±58m,经度方向为±4.3m,经卡尔曼滤波后其单点定位精度在纬度方向为±43m,经度方向为±3.6m;(2)北斗三星定位误差主要分布在纬度方向;(3)通过卡尔曼滤波可使北斗三星无源定位精度提高25%。     

DGPS在广西沿海海底地形测绘中的应用

DGPS（DifferentialGlobalPositioningSystem）测量技术即差分定位技术,包括实时差分和后处理差分定位技术,正在远海和近海测量中得到广泛应用。后处理差分定位与微波定位及GPS实时差分定位相比,具有作用距离远,不受基准台与船台之问的障碍物影响以及减少基准台等优点。对于近海大比例尺（大于1：1万）测量,可采用实时差分定位的方法,而小于1：1万中小比例尺海底地形图测绘及海上其他工程测量,采用后处理差分定位,既能满足精度要求,又能提高工作效率。本文主要介绍利用DGPS后处理定位方法,在测绘广西沿海1：5万海底地形图中的应用情况。     

A metrologic method of anomaly field amplitude bottom reduction in undersampled geomagnetic marine surveys

We show the results obtained by means of a seabed reduction technique on the intensity of geomagnetic anomaly fields applied to a synthetic case and then to the real case of a geomagnetic survey of eastern Ligurian Sea (Italy). The eastern Ligurian Sea has very intense short waves anomaly fields and a sea bed that varies greatly in depth. As a result the geomagnetic space signal is characterized by a very large spectral content; in these conditions it is not possible to obtain a full sampled marine survey and vertical continuation analytic procedures and standard numerical bottom reduction based on a single vertical incremental parameter, whichever is applicable, fails to give accurate results. The present technique, which has been fine-tuned over 4 years of experimentation in environmental researchs, aims to provide a simple and efficient means to reduce the distortion of geomagnetic anomalies field caused by the variation of distance between survey plane and magnetic outcrop source position. The compensation procedure is based on evaluation, by comparison of two measurements carried out at different altitudes, of the mean vertical increment typical of each anomaly field principal frequency component bands. The component anomaly fields are then corrected by application of the corresponding vertical increments and lastly, the anomaly geomagnetic field reduced to the sea-bed is computed as Inverse Fourier Transform of a spectrum built as synthesis of the component anomaly fields' spectra. The results obtained have shown a notable increase in definition of anomaly field intensity without the production of appreciable distortions or false geomagnetic echoes. This revised version was published online in November 2006 with corrections to the Cover Date.     

国外航海保障体系研究与启示

通过对以英国、美国和日本为代表的国外航海保障体系的研究,重点从组织结构与人员构成、技术支持与主要产品、质量管理与服务体系几方面分析了的国外航海保障体系的先进性,指出其对我国航海保障体系发展的启示之处,提出了我方的改进方向。