外测数据对流层折射误差修正及精度分析

针对对流层引起的航天器外测数据折射误差,基于对流层分段模型,以测站历史气象数据拟合折射衰减系数,建立测控站上空对流层折射率模型,并利用实测地面折射率对统计模型进行优化,进一步提高模型反映大气剖面的真实性.利用该模型对S频段多颗在轨卫星50多跟踪圈次的实测外测数据进行修正分析,并与微波辐射计实时修正结果进行比较,测距、测角、测速互差分别优于0.9m、0.02°、0.06 m/s.将该模型应用于卫星长管外测数据的实时修正,可提高轨道测量数据质量.     

提高深空异步激光测距精度方法研究

异步激光测距的作用距离远,有望实现对地球同步轨道以及深空航天器的精确测量。在对相关文献深入研究的基础上,全面分析了异步激光测距基本原理,对其钟差和测距公式进行了重新推导,提出了一种适用于深空异步激光测距的精确公式,并给出了迭代求解方法。通过理论仿真分析,在脉冲时间测量误差5ns时,对匀速飞行目标,该方法距离测量精度可达到5～6m,比其他方法高出2～3个数量级。     

光电经纬仪红外成像跟踪处理器的研究与实现

以高性能数字信号处理器TMS320C6203为核心,结合CPLD（可编程逻辑器件）进行逻辑控制,用FPGA（现场可编程门阵列）进行预处理,设计了实时目标检测和跟踪系统。介绍了实时图像处理系统的硬件组成、工作原理、软件流程,重点分析目标检测算法和系统实时性。该系统被成功用于光电经纬仪红外图像处理系统中,经试验证明,系统对弱小目标的检测、识别和跟踪能力达到实际工程的实时性需求,大大提高了数据采集能力与处理速度,采样精度得到很大提高,完全满足系统设计要求。     

MEMS梳齿音叉陀螺零偏漂移特性研究

由于MEMS（微机电系统）音叉陀螺多用于车载及无人机导航等应用场合,而外界温度环境因素对其零偏性能有着很大的影响,因此其零偏漂移的大小直接影响着最终导航的性能。本文研究了全温范围传感器漂移特性,旨在提升陀螺零偏稳定性。通过改进电路设计以及采用实时补偿算法对其全温范围零偏漂移进行补偿,将零偏稳定性提升了一个数量级。     

Detection of Projectiles by Electric Field Measurements

A number of various physical mechanisms cause aircraft, missiles, and projectiles to he electrically charged during free flight. The electric charge is in the 10-6 C range for aircraft and in the 10-10 C range for projectiles. The electric field thus transported provides information by which measuring the position and velocity of a projectile is possible. A measuring device is described to determine the position of a projectile in free flight while it is passing a target plane. The electric field distribution is measured by means of three electrodes in the manner of metal plates which are positioned in the proximity of the trajectory of the projectile. A mathematical formula can be derived to describe the coherence between the values measured of the electric field strength and the coordinates of the projectile. This measuring device consists of the target plane, 1 × 1 m2 in size, and the electric device controlled by a microprocessor. The measuring system has been tested with projectiles of the 4-30 mm caliber range and at velocities within the 50-1100 m/s range. The accuracy of the coordinates measured was found to be ± 7.5 mm.     

北斗/GPS双频载波相位单点定位模型及精度分析

针对海洋工程实时米级绝对定位需求,利用双频伪距、载波相位观测量和同时估计接收机位置、接收机钟差和载波相位模糊度,构建了一种双频载波相位实时单点定位方法.亚太区域14个测站试验结果显示:北斗水平和高程定位RMS分别为1.33m和1.81m,GPS为0.60m和0.85m,北斗/GPS组合为0.56m和0.72m;船载动态试验结果显示:北斗水平和高程定位RMS分别为1.40m 和2.46m,GPS为0.69m 和0.90m,北斗/GPS组合为0.65m和0.83m.     

Modeling and Estimation for Tracking Maneuvering Targets

A new approach to the three-dimensional airborne maneuvering target tracking problem is presented. The method, which combines the correlated acceleration target model of Singer [3] with the adaptive semi-Markov maneuver model of Gholson and Moose [8], leads to a practical real-time tracking algorithm that can be easily implemented on a modern fire-control computer. Preliminary testing with actual radar measurements indicates both improved tracking accuracy and increased filter stability in response to rapid target accelerations in elevation, bearing, and range.     

提高雷达测距精度的实用方法探讨

通过开展针对不同类型目标的雷达测距试验,得出雷达测距误差的一组数据。对其进行分析比较,总结出对于不同类型目标的雷达测距偏差产生的规律,给出了偏差的大致数量范围。     

Hardware-in-the-loop simulation technology of wide-band radar targets based on scattering center model

Hardware-in-the-loop(HWIL) simulation technology can verify and evaluate the radar by simulating the radio frequency environment in an anechoic chamber. The HWIL simulation technology of wide-band radar targets can accurately generate wide-band radar target echo which stands for the radar target scattering characteristics and pulse modulation of radar transmitting signal. This paper analyzes the wide-band radar target scattering properties first. Since the responses of target are composed of many separate scattering centers, the target scattering characteristic is restructured by scattering centers model. Based on the scattering centers model of wide-band radar target, the wide-band radar target echo modeling and the simulation method are discussed. The wide-band radar target echo is reconstructed in real-time by convoluting the transmitting signal to the target scattering parameters. Using the digital radio frequency memory(DRFM) system,the HWIL simulation of wide-band radar target echo with high accuracy can be actualized. A typical wide-band radar target simulation is taken to demonstrate the preferable simulation effect of the reconstruction method of wide-band radar target echo. Finally, the radar target time-domain echo and high-resolution range profile(HRRP) are given. The results show that the HWIL simulation gives a high-resolution range distribution of wide-band radar target scattering centers.     

双线程滑动窗口多系统GNSS超快精密定轨实现及评估

全球导航卫星系统（GNSS）超快精密定轨为GNSS实时应用提供了高精度空间基准。基于天地协同定位、导航与授时（PNT）网络服务中心实现了四系统GNSS卫星超快精密定轨,并对定轨结果进行精度评价。介绍了天地协同PNT网络的概念内涵以及网络服务中心部署的超快精密定轨软件架构和详细功能,并针对实时应用需求提出了一种双线程滑动窗口超快精密定轨策略。最后利用重叠弧段比较、与外部轨道产品比较以及卫星激光测距（SLR）检核3种方式对定轨结果进行了精度评价。结果表明,与武汉大学分析中心的最终事后精密轨道产品相比,四系统GNSS MEO卫星预报6 h弧段的径向均方根（RMS）误差整体在2~5 cm水平,BDS2 IGSO卫星最小一维RMS误差在10~15 cm水平;GPS和Galileo卫星的SLR检核残差均值在1~3 cm水平,标准差在3~6 cm水平,能够满足后续厘米级实时应用对空间基准的精度需求。     

High Range Resolution Profile Automatic Target Recognition Using Sparse Representation

Sparse representation is a new signal analysis method which is receiving increasing attention in recent years. In this article, a novel scheme solving high range resolution profile automatic target recognition for ground moving targets is proposed. The sparse representation theory is applied to analyzing the components of high range resolution profiles and sparse coefficients are used to describe their features. Numerous experiments with the target type number ranging from 2 to 6 have been implemented. Results show that the proposed scheme not only provides higher recognition preciseness in real time, but also achieves more robust performance as the target type number increases.     

基于Kohonen网络的动目标实时定位融合算法

为完成对动目标的实时定位测量,有效减小测控装备组网测量实时跟踪定位误差,在建立多定位子系统组网混合式融合结构模型的基础上,利用Kohonen网络的自组织特征映射模型特点,确定各组交会数据的权值,并将其输入1个Kohonen网络进行在线竞争、融合求得目标的位置信息,增强了目标实时位置信息的连续性、完整性,减小了实时定位误差。     

UAVSAR: New NASA Airborne SAR System for Research

NASA's Jet Propulsion Laboratory is currently building a reconfigurable, polarimetric L-band synthetic aperture radar (SAR), specifically designed to acquire airborne repeat track SAR data for differential interferometric measurements. Differential interferometry can provide key deformation measurements, important for studies of earthquakes, volcanoes, and other dynamically changing phenomena. Using precision real-time GPS and a sensor controlled flight management system, the system will be able to fly pre-defined paths with great precision. The expected performance of the flight control system will constrain the flight path to be within a 10 m diameter tube about the desired flight track. The radar will be designed to be operable on a Unpiloted Arial Vehicle (UAV) but will initially be demonstrated on a NASA Gulfstream III. The radar will be fully polarimetric, with a range bandwidth of 80 MHz (2 m range resolution), and will support a 16 km range swath. The antenna will be electronically steered along track to assure that the antenna beam can be directed independently, regardless of the wind direction and speed. Other features supported by the antenna include elevation monopulse and pulse-to-pulse re-steering capabilities that will enable some novel modes of operation. The system will nominally operate at 45,000 feet (13,800 m). The program began as an Instrument Incubator Project (IIP) funded by NASA Earth Science and Technology Office (ESTO).     

Design considerations for a real-time random-noise tracking radar

Random-noise radar has been applied successfully to range measurement, velocity estimation and terrain/target imaging. For applications involving stationary targets, long integration times and process averaging are easily tolerated. In situations where the target or radar platform moves at high speed, the impact of this relative motion on system design should be considered. This work addresses the statistical performance of a generic random-noise radar receiver and examines the inter-relationships between design parameters and performance tradeoffs. Complementing this examination, a random-noise monopulse system is also investigated as a possible architecture for real-time angle estimation. Simulations and numerical illustrations provide the basis of processor design and performance prediction.     

RSSI及TOF测距技术及仿真研究

无线传感器网络综合了嵌入式计算、传感器和通信等多种技术,可以实现对信息的获取与处理;借助其他辅助定位方式,可以实现对非合作目标的定位。而无线传感器网络测距技术是实现定位的基础。对TOF和RSSI这2种测距技术进行了深入的研究,比较这2种测距技术在不同范围内的测距效果,进而为工程应用提供理论基础。     

The White Sands Range and Range-Rate System

This paper discusses the concept, design, and design verification of the White Sands Range and Range-Rate System. Development of the system has been completed only through the design phase. The system is designed to meet requirements for high-accuracy midcourse tracking under severe target dynamics at the White Sands Missile Range. It is a multistatic Doppler and range tracker which operates at X band and incorporates transmitter, transponder, receiver, and baseline subsystems. The transmitter includes specially designed digital circuitry to synthesize test signals for target simulation during checkout of the system. The transponder signal is processed by a receiver which has been established theoretically to be the optimum realizable processor of continuous tracking data. The receiver incorporates specially designed carrier acquisition circuitry and digital VCO, and directly provides digital Doppler and tone phase data to facilitate real-time processing. The system utilizes data from other tracking systems at the Range for spatial acquisition, for aiding carrier acquisition in the receiver, and for resolving range ambiguities.     

转发式测轨系统地面设备时延测量方法

受地面设备时延误差的影响,转发式测轨系统的卫星定轨精度受到严重制约。为实现卫星精密定轨,地面设备时延误差的精确补偿至关重要,因此需要对地面设备时延进行精确测量。采用一种外环设备时延测量方法,实现对转发式测轨系统地面设备时延的实时测量。经过试验验证和分析,结果表明地面设备时延测量稳定度优于0.3ns,修正地面设备时延误差后的卫星重叠弧段的轨道差RMS值优于2m。     

基于足间距信息辅助的行人三维惯性定位算法

针对行人惯性导航系统误差随时间累积致使定位精度严重下降的问题,提出了一种基于足间距信息辅助的行人三维惯性定位算法。该算法在零速修正算法的基础上,利用足部安装的超声波测距模块实时测量行人双足相对距离,构建了基于超声测距的足间距约束模型,通过随机森林算法实现行人运动模式识别,并针对上下楼梯场景,利用台阶高度和足间距信息进行高度解算,最终实现行人三维惯性定位。在实际路线上开展了三维定位实验,数据显示,所提算法平面闭环误差为总路程的0.64%,与零速修正算法相比下降了55.56%,高度误差为0.06 m,与零速修正和气压计联合算法相比下降了64.70%,能够实现导航误差在总路程的0.50%以内的三维定位。实验结果表明,所提算法具有良好的工程应用价值。     

三向测量技术在深空探测中的应用研究

较详细地介绍了三向测量技术（包括三向测距和三向测速）,阐述使用三向测量的工程背景和重要意义,给出利用三向测量数据进行实时定位的数学推导,并分别对三向测距和三向测速原始数据的误差进行了分析;最后给出在＂嫦娥一号＂试验轨道段采用三向测量技术得到的残差分析结果。结果表明,在未进行站间时间同步的情况下,＂嫦娥一号＂卫星100km×100km环月轨道段三向测距误差约200m,三向测速误差约2cm/s,利用三向测量数据可以单独进行轨道确定,验证了我国后续深空探测中应用三向测量技术的可行性。     

GNSS广域差分改正数估计方法研究

随着我国北斗三号基本系统的正式运行,基于地面监测站的广域差分增强系统成为进一步提升卫星导航定位精度的手段之一。在码噪声多径误差修正(CNMC)的基础上,使用等效钟差方法实现GNSS卫星轨道与钟差误差的解耦,并依据卫星轨道运动的动力学特性,引入希尔差分方程描述卫星轨道误差变化,实现对轨道误差的实时卡尔曼滤波估计。基于GPS实测数据,对改正前后的用户等效测距误差(UERE)和定位精度进行了对比研究。实验结果表明,采用该方法,UERE标准差由改正前的0.456 m减小至0.227 m,降幅达到50.22%;整体水平定位误差(95%置信区间)由0.981 m减小至0.782 m,垂直定位误差(95%置信区间)由1.991 m减小至1.131 m,分别提升了20.29%和43.19%,差分改正效果明显。