基于圆形轨道的卫星位置递推方法

卫星无源定位系统对目标进行定位时,用于定位的卫星位置与时差或相位差等信息可能不同步,无法进行定位,需要把定位信息统一到同一时刻。针对这一问题,提出了基于圆形轨道的卫星位置递推方法,把卫星位置信息同其它信息统一到同一时刻,然后进行定位。该方法比常用的直线轨道递推方法误差更小,准确度更高,对提高定位精度具有较大应用价值。     

一种新型电涡流位置传感器

分析了现有位置传感器存在的问题,简要介绍了电涡流位置传感器的测量原理、性能优势和推广应用.     

基于宽带模糊函数的时差时间尺度联合估计

针对双站无源定位系统中的时差频差测量问题,从时差频差产生的根本原因入手,研究了利用宽带模糊函数对宽带雷达信号进行时差时间尺度联合估计的快速算法。仿真验证了算法的性能。结果表明,针对宽带信号,该算法有良好的时差时间尺度估计性能。     

基于量子海鸥算法的运载火箭回收舱段时差定位方法

火箭回收舱段的准确定位是实现运载火箭可重复使用的关键技术之一。针对运载火箭回收舱段飞行轨迹的特点,基于多站到达时间差(TDOA)无源定位原理,通过在回收舱段上加装主动辐射源设计了火箭回收舱段定位系统。将时差非线性定位方程求解问题转化为时差似然函数的极值优化问题,通过引入量子编码理论、混沌映射和遗传反向学习机制改进海鸥算法(SOA),将其用于搜索回收舱段最优定位信息。仿真结果表明:改进的量子海鸥算法在火箭回收舱段定位解算的早期收敛速度、定位精度、全局搜索能力等方面均优于传统Chan算法和标准海鸥算法。     

Approximate Maximum Likelihood Algorithm for Moving Source Localization Using TDOA and FDOA Measurements

 A closed-form approximate maximum likelihood (AML) algorithm for estimating the position and velocity of a moving source is proposed by utilizing the time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements of a signal received at a number of receivers. The maximum likelihood (ML) technique is a powerful tool to solve this problem. But a direct approach that uses the ML estimator to solve the localization problem is exhaustive search in the solution space, and it is very computationally expensive, and prohibits real-time processing. On the basis of ML function, a closed-form approximate solution to the ML equations can be obtained, which can allow real-time implementation as well as global convergence. Simulation results show that the proposed estimator achieves better performance than the two-step weighted least squares (WLS) approach, which makes it possible to attain the Cram閞-Rao lower bound (CRLB) at a sufficiently high noise level before the threshold effect occurs.     

利用二星TDOA和FDOA测量及辅助高度信息对地面目标的定位算法及精度分析

卫星探测定位系统对地面辐射源目标定位时,一般利用TDOA(到达时间差)测量,而当辐射源与卫星之间存在相对运动时,也可以测量FDOA(到达频率差).当辐射源的高程已知时,可以利用WGS-84地球椭圆模型作为精确定位模型.据此提出了利用两颗低轨卫星的TDOA及FDOA测量对地面辐射源定位算法,并对定位的算法进行深入的研究,同时推导了定位误差的分布模型.      

一种低空声源分布式定位系统及其算法与实验研究

低空声源目标具有较强的隐身性,为了实现对此类目标的定位,构建基于TMS320C6713平台的分布式麦克风阵列低空声源定位系统.麦克风阵列节点以DSP为核心处理器,通过A/D芯片采样麦克风阵列接收到的信号,通过到达时间差(TDOA)计算声源的角度,利用测向交叉法,融合多个节点的角度信息,计算出声源的位置.结果表明:在时延估计精确的情况下,对低空目标具有较好地估计;系统具有较高的精度和稳定性,能够满足对低空声源目标进行定位的实际需求.     

运载火箭的双星定位方法研究

一般地,仅凭两颗ＴＤＲＳ跟踪测距信息无法确定空间运动目标的三维位置,必须借助其它辅助信息。文章总结了可供借用的６类辅助信息;并以运载火箭为研究对象,构造了借助理论弹道解算火箭飞行轨迹的计算方法;分析了测距误差和理论弹道偏差对定位的影响;并通过仿真计算验证了该方法的有效性。     

Impact of gravitation on gaseous pollutant source identification

 It is necessary to identify a gaseous pollutant source rapidly so that prompt actions can be taken, but this is one of the difficulties in the inverse problem areas. In this paper, an approach to identifying a sudden continuous emission pollutant source based on single sensor information is developed to locate a source in an enclosed space with a steady velocity field. Because the gravity has a very important influence on the gaseous pollutant transport and the source identification, its influence is analyzed theoretically and a conclusion is drawn that the velocity of fluid is a key factor to effectively help weaken the gravitational influence. Further studies for a given 2-D case by using the computational fluid dynamics (CFD) method show that when the velocity of inlet is less than one certain value, the influence of gravity on the pollutant transport is very significant, which will change the velocity field obviously. In order to quantitatively judge the practical applicability of identification approach, a synergy degree of the velocity fields before and after a source appearing is proposed as a condition for considering the influence of gravity. An experimental device simulating pollutant transmission was set up and some experiments were conducted to verify the practical application of the above studies in the actual gravitational environment. The results show that the proposed approach can successfully locate the sudden constant source when the experimental situations meet the identified conditions.     

三星时差定位系统的有源校正算法

针对三星时差（TDOA）定位系统中,由星历误差和时间同步误差导致无法精确定位的问题,提出一种基于正交投影的两步迭代有源校正算法。该算法首先利用正交投影将时间同步误差从观测方程剔除,然后引入一个与辐射源位置和星历误差有关的中间变量,通过对中间变量的最优估计消除星历误差对定位精度的影响,最后利用中间变量求解出目标辐射源位置。仿真结果表明,所提算法定位性能的仿真值和理论值均可以达到克拉美-罗界（CRLB）,当TDOA观测噪声较小且有3个以上参考源时,可以完全校正星历误差和时间同步误差对定位精度的影响。