基于卫星多角度观测的气溶胶遥感反演算法研究进展

对国际上双角度、多角度及偏振卫星气溶胶遥感反演算法的最新研究进展进行了综述.双角度遥感作为多角度遥感的一种典型情况,算法的核心思想同样适用于两个传感器在几乎同时对同一地区进行观测的情况.以双角度观测的沿轨扫描辐射计(ATSR)系列传感器为例,总结了 ADV(ATSR dual view)、SU(Swansea Univ...     

Accurate geometric correction of ATSR images

An accurate geometric correction algorithm of raw ATSR images is proposed in this paper. The proposed algorithm is divided into two modules: pre-correction and precision correction. In the pre-correction algorithm, the scanning geometry of the ATSR, ephemeris data and the Earth's shape and rotation were modeled mathematically. It corrected elliptically-distorted raw ATSR images and resulted in a mean collocation error of 1 pixel between the nadir and forward images. The proposed navigation model showed a better geolocation performance than ATSR image geometric correction algorithms currently in operation. The geometric errors in the pre-corrected images were reduced further by the precision correction algorithm. Coastlines were detected from the pre-corrected nadir and forward images and matched with map coastline data. The matched coastline pixels, GCPs, were combined with the pre-correction model to estimate the errors of the position, velocity and attitude of the satellite. An extended Kalman filter was used for the optimal estimation. The corrected images showed the collocation error of 0.4 pixel and the geolocation error of 0.7 pixel. The results were compared with those from a polynomial warping technique. It proved that the proposed precision correction algorithm gave better geometric correction performance than collocation algorithms based on a polynomial warping technique     

一种极化-多普勒气象雷达的射频干扰滤波方法

为了滤除极化-多普勒气象雷达中的射频干扰,该文提出利用谱极化滤波器,适用于同时发射同时接收(STSR)和分时发射同时接收(ATSR)体制的极化气象雷达。首先利用C波段STSR气象雷达的实测数据研究射频干扰的时域、频域和极化域特性,建立射频干扰信号模型。然后,在X波段ATSR雷达的数据中仿真加入射频干扰,验证谱极化滤波器的有效性。总体看来,在ATSR雷达中利用谱极化滤波器可以有效保留降雨目标并且滤除射频干扰。最后,针对STSR雷达提出利用数据分集的方法,STSR雷达的实测数据可以模拟ATSR雷达数据,再利用谱极化滤波器实现射频干扰滤除,同样可以取得较好的滤波效果。      

Atmospheric corrections in the thermal infrared: global and watervapor dependent split-window algorithms-applications to ATSR and AVHRRdata

The split-window method is an appropriate way to perform atmospheric corrections of satellite brightness temperatures in order to retrieve the surface temperature. A climatological data set of 1761 different radio soundings, the TIGR database, has been used to develop two different split-window methods. A global quadratic (QUAD) method, with global coefficients to be applied on a worldwide scale, and a water vapor dependent (WVD) algorithm. The first method includes a quadratic term in the split-window equation that roughly accounts for the water vapor amount. The other method explicitly includes the water vapor amount in each split-window coefficient. When applied to the 1761 radio soundings, the latter method gives better results than the global one, especially when the surface emissivity is far from unity (0.95 or less) and when the water vapor reaches great values. Both algorithms have been tested on ATSR/ERSI and AVHRR/NOAA data over sea pixels. The QUAD algorithm gives correct results for simulations (the standard error is 0.2 K) and experimental data (the bias ranges from -0.1 to 0.4 K). The WVD algorithm appears to be more accurate for both simulations (the standard error is less than 0.1 K) and AVHRR experimental data when climatological water vapor contents are used (the bias ranges from -0.2 to 0.1 K)     

光学遥感卫星杂散光扫描测试系统

为了实际测量、验证光学遥感卫星的杂散光抑制能力,分析某些特殊卫星的成像轨道和时间特点,研制了一套基于7维大型机器人的光学遥感卫星杂散光扫描测试系统。根据卫星全年太阳照明几何条件,通过建立的光束扫描子系统各机构的控制方程构建照明光束的扫描位置、方位角（-90~+90）和俯仰角（-29~+42.5）,精度分别达到10 mm、0.2和0.1。消光子系统采用反射率低于1.5%（400~1 600 nm）的材料和大消光比结构,极黑目标模拟器消光比可达9.910-7。研制的光学遥感卫星杂散光扫描测试系统能够满足目前大部分光学遥感相机的杂散光测试、分析和验证要求。     

卫星移动通信中的电扫描阵列天线

90年代以来，卫星移动通信发展异常迅速。许多科研组织都对移动地面站中的电扫描阵列天线进行了研究。介绍了目前已经开发并应用于卫星移动通信的几种电扫描阵列天线及其技术细节。     

The GLOBCARBON Cloud Detection System for the Along-Track Scanning Radiometer (ATSR) Sensor Series

The GLOBCARBON initiative aims to develop a service to generate fully calibrated estimates of at-land products using, in combination, data from the Along-Track Scanning Radiometer (ATSR) sensor series, MERIS and VEGETATION. A fundamental requirement of such processing is the effective removal of extraneous effects introduced by cloud, cloud shadow, snow, and atmosphere in these data. This paper reports on the implementation and extension of a new cloud and snow processing system for land, which is for the ATSR sensor series. The snow processor is as implemented for the Moderate Resolution Imaging Spectrometer, whereas the cloud processor is based on APOLLO, with extensions to generate the probabilities of cloud presence and a further test to eliminate the cloud missed by APOLLO. The system was tested on 48 images representing a wide range of cloud types and forms over three contrasting biomes-boreal forest, desert savannah, and tropical evergreen forest. Excellent results are produced and represent a major improvement over the original flagging system. The approach has been adopted in GLOBCARBON for the processing of 500 000 ATSR scenes and 20 000 AATSR striplines.     

新型数字卫星接收机的寻星功能

分析近几年来推出的新型数字卫星接收机的寻星功能包括寻星指示和接收参数扫描两大功能，以及这些功能特点在寻星操作中的运用。     

新型数字卫星接收机的寻星功能

分析近几年来推出的新型数字卫星接收机的寻星功能包括寻星指示和接收参数扫描两大功能,以及这些功能特点在寻星操作中的运用。     

Brightness temperature of microwave self-radiation employed as direct characteristic of the dynamic interaction between the ocean and atmosphere

It is proposed and substantiated that, in the ocean?atmosphere system, the microwave self-radiation intensity (brightness temperature), which is measured by means of satellites in the millimeter and centimeter wave bands, can be used as the direct characteristic of the thermal and dynamic parameters of the system. The vertical turbulent fluxes of sensible and latent heat and momentum are determined at the ocean?atmosphere interface according to the data measured by the special sensor microwave imagers located on weather satellites created in the scope of the defense meteorological satellite program and the advanced microwave scanning radiometer installed aboard the EOS Aqua oceanographic satellite. For the first time, the integrated (annual) characteristics of heat exchange between the ocean and atmosphere are investigated in the energy-active zones of the North Atlantic with the help of long-term satellite microwave radiometric measurements.     

动态处理结合非线性设备的虚拟低音增强系统

现代声学产品由于物理尺寸的限制,在低频很难达到令人满意的效果。通过虚拟低音的方法,可以诱发人脑从各个谐波中感知到基频,极大地提升了人对低频的主观感受。非线性设备(Nonlinear Device,NLD)是基于时域的一种主流处理方法,不同类型的NLD会产生不同的谐波特性,其中基于ATSR(Arc-Tangent and Squire Root)方法可以同时产生奇次和偶次谐波,但谐波比例与输入信号幅值相关,通过在ATSR方法前增加动态处理模块可以进行有效的谐波成分控制,实现了对不同幅值输入信号低音增强的灵活控制。     

一种动中通地面跟踪系统的FPGA实现

针对动中通系统在跟踪状态下可能失去空中目标、纯机械扫描系统搜索速度慢等问题,设计了一种基于现场可编程门阵列(FPGA)的新型动中通地面系统.系统天线接收的信号经射频处理输入数字信号处理器,运算得到相关信息,以判断目标方位.上位机控制整个系统的工作状态,有良好的人机交互,系统可在失去空中目标后快速搜索或跟踪.水平方向上由直流电机驱动天线阵对360°方位扫描覆盖,俯仰方向上采用不同角度的波束切换,在短时间内依据能量准则定位空中目标方位,提高了动中通系统的运行效率.     

无信标星间激光通信系统粗精复合扫描方法

无信标星间激光通信系统无需额外设置信标光组件,直接采用小束散角的信号光进行瞄准捕获跟踪,有利于降低终端的质量、体积、功耗和制造成本等重要指标,满足商业航天和低轨卫星空间激光网络的发展要求。为了克服现有无信标激光通信系统扫描时间长、捕获难度大的问题,综合考虑星上姿态变化、测量精度和终端安装定位误差等因素,对扫描不确定域进行了数值计算,设计了无信标扫描捕获流程,定量分析了粗精扫描机构控制带宽、扫描步长、规划路径与光束覆盖面积的耦合关系,提出了一种简单可靠的无信标粗精复合螺旋扫描方法。典型环境仿真结果表明,采用所提方法平均扫描捕获时长小于20 s,捕获概率大于95%,有效提升了无信标系统的扫描效率,可满足未来低轨卫星空间激光网络的快速建链要求。     

Earth Observing System AM1 mission to Earth

In 1998, NASA launches EOS-AMI, the first of a series of the Earth Observing System (EOS) satellites. EOS will monitor the evolution of the state of the earth for 18 years, starting with the morning observations of EOS-AM1 (10:30 a.m. equatorial crossing time). An integrated view of the earth, as planned by EOS, is needed to study the interchange of energy, moisture, and carbon between the lands, oceans, and atmosphere. The launch of EOS-AM1 and other international satellites marks a new phase of climate and global change research. Both natural and anthropogenic climate change have been studied for more than a century. It is now recognized that processes that vary rapidly in time and space-e.g. aerosol, clouds, land use, and exchanges of energy and moisture-must be considered to adequately explain the temperature record and predict future climate change. Frequent measurements with adequate resolution, as only possible from spacecraft, are key tools in such an effort. The versatile and highly accurate EOS-AM1 data, together with previous satellite records, as well as data from ADEOS, TRMM, SeaWiFS, ATSR, MERIS, ENVISAT, EOS-PM1, Landsat and ground-based networks is expected to revolutionize the way scientists look at climate change. This article introduces the EOS-AM1 mission and the special issue devoted to it. Following a brief historical perspective for an insight into the purpose and objectives of the mission, the authors summarize the characteristics of the five instruments onboard EOS-AM1. Specifically, they concentrate on the innovative elements of these five instruments and provide examples of the science issues that require this type of data     

超声电机驱动的轻量化扫描机构高精度控制

为实现卫星高分载荷扫描驱动机构的轻量化,以超声电机为驱动部件,设计了一款扫描驱动机构,质量仅为传统的步进电机加谐波减速器驱动方案的15%。构建了扫描驱动机构驱动控制器,配合21位绝对式光电编码器作为位置反馈传感器,对扫描驱动机构高精度控制方法进行了研究。针对超声电机在精密控制中的非线性及时变性,在对比总结比例、积分、微分(PID)控制、模糊控制、神经网络PID控制算法的基础上,设计了一种基于专家规则的PID控制器,并结合超声电机实时温度作为前馈控制在线调节控制器控制参数,最后进行了指向控制和速度稳定度实验研究。实验结果表明：令扫描驱动机构指向20°时,稳态指向精度优于2″,在3.3 r/min情况下扫描驱动机构速度稳定度优于±1%,能够满足卫星载荷对扫描驱动机构高精高稳的控制需求。     

光控相控阵天线在卫星通信领域的应用前景（特邀）

简要回顾了光控相控阵天线的发展历程,介绍了光控相控阵天线的工作原理,探讨了光控相控阵天线在卫星载荷领域的应用优势。指出高通量卫星超宽带应用和多功能载荷多频段应用是卫星通信的发展趋势之一,光控相控阵天线在大口径、超宽带、宽角扫描方面的应用优势明显。     

A satellite data transmission antenna

A retrodirective satellite antenna for a broad bandwidth, satellite-to-ground data transmission link, is described. An information-collecting satellite which transmits its data in the direction of the ground receiver upon command, is considered. The satellite antenna described for this system is an active retrodirective antenna which utilizes the beam-forming characteristics of a phasing matrix. A signal from the ground station is received on a particular beam port of the matrix which corresponds to a particular beam-pointing direction. Control circuitry in the satellite activates a switching matrix and a transmitter so that the data-carrying signal is transmitted in the same direction from which the satellite is interrogated. Other retrodirective techniques in addition to the phasing-matrix antenna are evaluated in terms of their relative merit. The systems considered include the active Van Atta array, the automatic three-dimensional electronic scanning, antenna (ATHESA), the Luneberg lens and various other antenna array techniques.     

A comparative analysis of frequency scanning and multispot beam satellite systems for mobile communications

A comparative analysis between frequency scanning and multispot satellite systems has been performed in the context of land mobile applications. The aim of the work has been to confirm the effectiveness of the frequency scanning approach, whose technical feasibility has already been proved by the authors in a previous study, also in a comparative investigation with a more conventional satellite configuration. A proper comparative methodology has been established to compare two baseline configurations of the two systems. The analysis has also been rendered parametric, varying some system characteristics such as bandwidth, traffic distributions and linearity requirement. The achieved results are provided and widely commented on in the paper.     

一种低轨卫星通信终端的数字波控方法

针对低轨卫星通信场景下地面终端需自动追星的问题,提出了基于相控阵的波束控制方法.首先利用卫星的位置以及终端的位姿信息计算终端对星的初始指向角,并用该指向角计算相控阵各阵元的移向量完成初始对星,然后利用相控阵在数字域进行圆锥扫描实现对星的精跟踪.仿真结果表明,所提方法能较好完成终端的对星工作.     

湖泊水质卫星遥感方法及其应用

通过系统性的常规水质采样分析与水面光谱测量外场同步试验,建立了由FY-1C多通道扫描辐射计、Landsat卫星TM和Seastar卫星SeaWiFS等在轨卫星多通道遥感器以及一组设想的遥感通道遥感反演叶绿素a浓度和总悬浮物浓度的优化通道组合模型,提出了一种利用水面上标准反射板的反射光谱和遥感图像本身确定大气透过率和反射率从而实现大气校正的水质指标卫星遥感反演方法．所建立的模型和方法被用于遥感解译我国典型富营养化湖泊太湖和滇池从80至90年代的富营养化程度及其分布状况随年份的变化．本项研究为进一步开展湖泊水质业务化卫星监测打下了基础．