Cloud and precipitation remote sensing at 94 GHz

The use of short millimeter-wave Doppler radars for the observation of clouds and precipitation is discussed. Attenuation and scattering (including Mie backscattering by raindrops) of this short-wavelength radiation by hydrometers is discussed as well as the sensitivity of such radars for the observation of clouds     

面向毫米波遥感成像的双极化毫米波探测器

针对多极化毫米波遥感成像重大需求,报道了一种高集成度双极化毫米波探测器。探测器采用固态电子学方案,通过喇叭天线接收毫米波信号,利用正交模耦合器进行极化信号分离,采用两级低噪放芯片放大信号,通过肖特基二极管实现功率检测。每支探测器集成两路接收通道,每个接收通道可同时探测水平与竖直两个极化方向信号。经测量,探测器探测频段为W波段(75～110 GHz),平均等效噪声温差达到0.3 K(@10 ms),尺寸不足155 mm×15 mm×20 mm,质量<0.3 kg。利用该探测器实现城市环境双极化毫米波遥感成像,成像结果表明,相比于单极化遥感成像,双极化遥感成像可以获得更多极化信息,可对城市环境下常见物品进行突出显示,这有助于今后进行自动物品识别、轮廓提取与远程物质成分识别。     

亚米级全色遥感影像云地检测算法研究

为解决现行云地检测算法不适用于亚米级全色遥感 影像云地检测的问题,提出一种大尺度自适应匹配阈值(LS-AMTH,large-scale adaptiv e matching threshold)算法。算法构建包含光谱、纹理 与边缘特征的特征参量集,利用提升算法对影像子块进行大尺度云地分类;之后对大尺度分 类所得云地子 块进行阈值的自适应匹配选择,最终实现像素级云地区域检测并统计云地占比。试验表明, 针对亚米级全 色影像,本文算法准确度达97.3%,在复杂云地混合区域取得良好检 测效果。     

Analysis of polarization diversity at digital TV indoor receivers

The reduction of signal fading by using polarization diversity at a digital terrestrial TV receiver is evaluated. Two different diversity techniques, one operating at carrier (TV channel) level and the other at subcarrier level, are compared. A measurement campaign has been carried out in three different indoor environments using two antennas with orthogonal linear polarizations at the receiver. The polarization diversity gain has been calculated when the maximum selection technique is used. As expected, the level crossing rate and the average fade duration are considerably reduced by the diversity system     

基于GPU的遥感图像前期处理算法研究与应用

针对传统的遥感图像前期处理算法在面对海量地面数据时计算时间很难满足需求的问题,基于RPC模型的遥感成像几何校正算法的并行加速和基于SIFT特征提取的图像匹配技术的并行加速研究。针对几何校正的主要步骤及其速度瓶颈问题,提出了可采用的并行加速方法,同时结合SIFT的特点提出了并行优化加速的方案。采用基于数据划分的并行方法对遥感图像的几何校正和SIFT特征提取算法进行加速。最后利用CUDA环境,在CPU+GPU异构系统下,设计试验对两个算法优化并行提速,试验结果表明,提出的加速方案和优化算法能大幅提高遥感图像的前期处理效率。     

卫星遥感与6G通信遥感一体化

卫星遥感是人类实现高分辨率对地观测的重要手段,已逐步成为支撑经济社会发展以及国防安全的重要组成。6G追求通信遥感计算深度融合,通信遥感一体化成为其重要的特征。回顾了国内外卫星遥感的发展历程,概述了卫星遥感系统现有的体系结构和6G时代通信遥感一体化体系架构,阐述了人工智能驱动的典型卫星遥感技术和最新研究进展。针对6G时代卫星通信遥感一体化的趋势,探讨了实现“一星多用、多星组网、多网融合、智能服务”组合型发展的技术挑战和发展趋势。     

航天光学遥感成像半实物仿真系统研究

航天光学遥感器的研究周期长、成本高,为了保证航天遥感卫星在轨成像性能,在卫星发射前,必须在地面进行深入可靠的仿真试验研究。本文建立了由六自由度机械臂为运动平台的航天光学遥感成像半实物仿真系统,首先建立坐标系模型并求取坐标转换参数,然后依据STK(System Tool Kit)软件生成星历数据,经坐标转换后输入到机械臂控制系统,最后根据TDI CCD相机的成像原理,控制机械臂使TDI CCD相机对三维地形沙盘线性推扫,从而获取线阵仿真影像。仿真结果表明,建立了正确有效的仿真坐标系,可快速、稳定、实时地模拟航天遥感对地推扫成像过程,且仿真影像中均匀分布的12个圆形靶标的圆度均优于0.95,证明仿真影像质量较高,可满足遥感目标的探测与识别仿真算法研究的需求,为航天光学遥感成像仿真系统的研究提供一定参考。     

遥感相机的智能调焦方法

为了将基于图像处理的智能调焦方法引入到空间遥感相机中,从而提高其在轨调焦能力,提出了采用辅助CCD的遥感相机智能调焦方法。该方法解决了推扫式遥感相机由于图像动态变化导致的比较基准不确定问题,为智能调焦方法在遥感相机中的应用开创了途径。在阐述基本调焦原理的基础上,给出了实际应用中多片CCD级联时评价区域选择依据和算法,并以Variance函数为评价函数对调焦过程进行了仿真模拟,实验结果表明:该方法能够可靠、自动地搜索到最佳聚焦位置,获取清晰图像,适用于遥感相机使用。     

数字遥感图像清晰度评价研究

清晰度作为衡量数字图像质量的重要指标,现有的评价方法仍不够成熟。经对当前主要的图像清晰度评价方法分析研究,提出一种基于边缘对比度的遥感图像清晰度评价方法,并进行了实验数据分析。结果表明,该评价方法客观、高效,既能够对不同模糊程度的同一图像内容进行清晰度评价,也能在一定程度上对不同内容的遥感图像进行评价,具有很高的实用性。     

Optical remote sensing of the earth

Optical remote sensing of the earth from aircraft and from orbit has made unique contributions to understanding the dynamics of the atmosphere, oceans, and the vegetation cover of the land, as well as provided new perspectives in the study of the solid earth. This paper encompasses optical remote sensing of the earth's surface in the region of 0.4 to 15 µm and is divided into four areas: principles, applications to science disciplines, recent sensor history, and new technology developments. The latter developments promise to revolutionize the methods used and the types of problems addressed with remote sensing techniques.     

一种面向低轨遥感星座的路由任务规划算法研究

为了解决遥感星座数据传输时效性差的问题,利用星间链组网,提出了一种适应于断续猝发特征星间网络的路由任务规划算法。该算法以遥感卫星成像任务规划结果为驱动,结合卫星网络拓扑结构的时变性特点,改进基于快照序列的拓扑划分方法,降低路由切换频率,减少链路切换代价损失。并将卫星与地面站之间的路由看作低轨遥感星座路由的一部分,在选择星地最短路由路径的同时实现星地建链总时长最大化。仿真结果表明,该算法能够显著提升低轨遥感卫星星座的数据传输能力。     

A C-band scatterometer for remote sensing the air-sea interface

An airborne C-band scatterometer system (C-Scat) has been developed to remotely sense ocean surface winds and improve upon the present understanding of the relationship between normalized radar cross section (NRCS) and ocean surface roughness influences such as wind speed and direction, wave height and slope, and the air-sea temperature difference. The scatterometer utilizes a unique frequency-steered microstrip array antenna that is installed beneath the fuselage of an airplane. The antenna is electronically scanned in elevation, from 20° to 50° off-nadir, and mechanically spins in azimuth. The system is capable of measuring ocean surface NRCS from altitudes as high as 25000 ft. The system is divided into four subsystems: the transmitter and receiver, the spinning antenna, the computer control and data acquisition subsystem, and the digital and analog interface electronics     

遥感卫星数据接收天线抗阵风扰动技术研究

为解决阵风扰动对遥感卫星数据接收站窄波束天线跟踪性能的影响问题,采用安装天线罩抗风、使用大惯量电机增加天线转动惯量以及优化跟踪策略等方法。通过阵风扰动建模、伺服电机与传动机构建模、控制环路建模以及Matlab仿真,得出减少阵风扰动影响的几种方法,比较几种方法的适用范围、优缺点和可实现性,得出解决遥感卫星数据接收站窄波束天线抗阵风扰动的结论,为以后的工程项目建设提供参考。     

遥感方向的增强现实软件技术研究

增强现实技术是将计算机渲染生成的虚拟场景和真实世界中的实际场景无缝结合起来的一种全新技术。得益于计算机技术的高速发展,人们通过计算机与世界交流和接触的实际愿景更加需要实践发展的机会,因而增强现实技术便是在这样的现实环境中获得了较大的发展,增强现实作为下一代人机交互的重要发展方向,具备很好的研究价值。文章从增强现实软件的现实发展状况入手并整合遥感方向的相关应用进行了基于遥感的增强现实软件技术的研究,旨在为增强现实技术的发展提供全新的方向。     

The theory of polarization diversity systems: the partiallypolarized case

A detailed consideration is presented of copolarized and cross-polarized radar response for partially polarized scattering. A technique using an adjustable polarization basis is used where appropriate. Conditions for maximum and minimum copolarized and cross-polarized power return are obtained. Necessary and sufficient conditions for the realization of the polarization fork are presented     

Limits of space-based remote sensing for methane sourcecharacterization

This analysis examines the ability of a space-based instrument to identify and quantify methane sources in the presence of temperature, humidity, and albedo uncertainty. Thus, the objective is to quantify in the context of the NASA Earth Observing System (EOS) the synergistic benefit of simultaneous observation of the Earth's surface with atmospheric attributes. The analysis is illustrative of the type of examination that should inform remote sensing policy and system configuration decisions. The retrieval technique considered is linear inversion of near-IR spectral signals. The anticipated range of methane mixing ratio enhancement due to sources at the Earth's surface is compared to the detection limit of the space-based instrument     

星载微波辐射遥感的极化指数距平统计与土壤湿度分布

用辐射传输理论提出的地表微波辐射极化指数PI的定义,分别指出了土壤湿度、地面粗糙、植被层和大气层的各自影响.用DMSP SSM/I多时相6年的数据给出中国主要陆地19.35GHz通道的PI值月平均分布,表征土壤湿度的月变化,并获得中国主要陆地同季同月PI距平值△nPI的统计分布,展示了中国陆地土壤湿度变化的分布图,以及在干旱与水涝期间PI距平值的异常,用中国山西2001年5月的干旱和中国长江中游1998年8月水涝作了个例证明.这一理论方法可同样推广到有较低频率(如10.7GHz)的2002年5月发射的AMSR-E或中国风云系列卫星微波成像辐射计的通道,而获得土壤湿度分布更好的PI指数评估.在已知区域平均PI值与平均土壤湿度的条件下,可以定量反演该区域的土壤湿度,并用TRMMTMI实验数据进行了验证.     

FOPAIR: a focused array imaging radar for ocean remote sensing

FOPAIR, a FOcused Phased Array Imaging Radar, provides high-resolution X-band images of the ocean surface. The system is designed to provide high-speed imagery (up to 180 frames/s) for short range applications (50-400 m) from a fixed platform such as a pier or tower. FOPAIR employs a fast, sequentially sampled antenna array and uses a software-based beamforming technique to generate high resolution imagery without the need for multiple radar receivers or beamforming hardware typical of active phased arrays. A summary of the principles of operation and the design of the instrument is given, followed by examples of FOPAIR's imaging capability. To the authors' knowledge, these examples include the highest-resolution, highest-speed microwave images of the ocean surface produced to date. A brief comparison between FOPAIR and synthetic aperture radar techniques is also included