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1.
星载微波成像仪数字仿真技术   总被引:2,自引:2,他引:2       下载免费PDF全文
星载微波成像仪是卫星遥感技术中获取信息的重要仪器,其性能直接影响整个卫星系统。由于在真实系统上直接试验的风险和代价太大,所以数字仿真技术成为一种行之有效的手段。提出了星载微波成像仪数字仿真的设计思想和目标;详细介绍了数字仿真实现的方法和仿真模型框图;描述了星载微波成像仪数字仿真研究的预期结果。  相似文献   

2.
星载微波成像仪接收通道的仿真研究   总被引:2,自引:0,他引:2       下载免费PDF全文
星载微波成像仪接收通道即微波辐射计,是星载微波成像仪的核心部分。对其进行仿真研究的关键和基础是信号处理方法。给出了接收通道各环节的数学模型;采用快速离散富里叶变换处理信号;分析并缓解了由于离散富里叶变换带来的频率分辨率与样本点数之间的矛盾;以全功率微波辐射计为例进行了仿真研究并给出了结果。为进一步实现系统仿真调试和环境仿真调试奠定了基础,并为其它类型微波辐射计的仿真研究提供了借鉴。  相似文献   

3.
本文对一种以全功率微波辐射计为基础的新型微波辐射计———数字增益自动补偿微波辐射计进行了仿真研究。建立了微波辐射计系统各环节的数学模型并以此进行了仿真试验。仿真结果不仅证明了所建立的数学模型准确有效,而且为优化系统设计提供了重要参考,同时也为进一步实现星载环境仿真调试奠定了基础。  相似文献   

4.
星载W波段毫米波辐射计研究   总被引:1,自引:0,他引:1  
在863-2项目支持下,开展了W波段毫米波辐射计的研究。其工作中心频率为90.5 GHz,带宽为2 GHz,积分时间为200 ms时其系统灵敏度达到0.6 K,线性度优于0.999。这些技术指标基本达到了星载应用的要求。为配合扫描成像研制了两套天线系统,一套为Cassegrain天线,另外一套为二元光学天线,它是利用光学衍射原理制成的位相型Fresnel波带片。二元天线具有设计灵活、加工方便、体积小、重量轻、旁瓣电平低和安装方便等优点。W波段微波辐射计系统在实验室内进
行了扫描成像试验,取得了W波段微波辐射计扫描图像。  相似文献   

5.
在星载雷达高度计的测量中,天线的误指向角对测量结果影响很大。采用非线性最小二乘方法(nonlinear least square,NLS),从雷达高度计回波波形中进行误指向角估计,理论分析和仿真结果表明该方法估计的精度满足补偿要求。利用上述估计结果,还提出了一种补偿方法,用以矫正由天线误指向角引入的高度计测高误差,从而提高了测高精度。  相似文献   

6.
干涉式被动微波成像仪(干涉式综合孔径微波辐射计)利用不同距离的干涉天线对形成的基线对视场范围内亮温分布的空间频谱进行采样,进而反演得到亮温图像。首先介绍了干涉式被动微波成像仪的基本工作原理,在此基础上分析了空间图像的二维频谱特征,并能利用这些特征从采样频谱中初步分析出原始亮温中的某些特殊分布,证实了在反演亮温存在明显振荡的情况下,可以从振荡方向判断存在误差的基线的大致位置。还分析了成像仪的天线位置误差、信道的幅度和相位误差以及天线方向图误差对反演亮温的影响及特点。这些分析将为从反演图像判断干涉式被动微波成像仪误差类型和来源提供重要的判别依据,并为后续的反演图像增强算法的设计提供重要的参考。  相似文献   

7.
星载天线热分析系统研究与开发   总被引:7,自引:3,他引:7  
朱敏波  何恩  曹峰云 《计算机工程与设计》2004,25(12):2251-2252,2267
为了保证星载天线能在太空热辐射环境正常工作,针对星载天线在轨工作的特征,阐述了热分析技术在星载天线设计工作中的重要性,通过对星载设备热分析方法的研究,分析了常用热分析软件在空间热分析方面的功能和技术特点,提出了星载天线热分析的方法和基本步骤。该方法已在星载可展开天线热分析软件开发中得到应用。  相似文献   

8.
为了提高传统星载真实孔径雷达(微波散射计)空间分辨率、满足地球物理参数(雪水当量、冰雪冻融等)的观测需求,开展了扫描体制散射计的高分辨率分析和研究。基于距离向脉冲压缩处理和方位向多普勒处理技术,提出了一种旋转扫描体制下的分辨率提高方法。针对笔形波束圆锥扫描散射计的观测方位角在天线扫描过程中不断变化的特点,在正侧视和斜侧视时对模型分别进行了仿真验证。验证表明利用散射计旋转扫描多普勒信息能够建立与方位向分辨率的关系,可以有效提高微波散射计的空间分辨率。当正侧视时,方位向分辨率可以达到2km,斜前视或者斜后视时,方位向分辨率能够达到2~5km。针对雪水当量模型数据进行分析验证,设计的系统传递误差Kpc在5km分辨率下可以达到0.3,在2km分辨率下达到0.3~0.5。  相似文献   

9.
2010年11月5日发射升空的我国新一代极轨气象卫星FY-3B (“风云三号”B星)携带的微波成像仪,可以全天候获取来自地球表面和大气的电磁辐射信息。针对在轨测试期间微波成像仪1.7 s和1.8 s两种扫描周期,详细比较了二者图像质量的差异。在图像质量评价研究中,使用统计方法比较了图像的动态范围;通过功率谱计算,对比了图像的空间纹理特征;通过信息熵计算,分析了图像信息量的不同;此外,还研究了图像的对比度以及通道间配准的情况。结果表明:1.7 s图像的空间纹理结构、高频图像的对比度以及通道间配准明显优于1.8 s,表明1.7 s扫描周期下的图像质量优于1.8 s,该结论可以作为微波成像仪仪器指标设计的参考。  相似文献   

10.
FY-3卫星微波成像仪用于大气微波遥感、海洋微波遥感和陆地微波遥感,是气象、海洋和灾害监测的重要遥感手段之一。微波成像仪在轨运行时能否获取有价值的探测资料,得到定量化的应用和真正的业务使用,主要取决于微波成像仪能否进行精确定标。而非线性偏差的大小又直接与微波成像仪定标精度的大小有关。主要分析了影响微波成像仪非线性偏差的因素,以及降低微波成像仪非线性偏差的方法,并给出了微波成像仪各通道真空定标下非线性偏差。  相似文献   

11.
全极化微波辐射计是一种新型的被动微波遥感仪器,可以测量海面辐射的全部4个Stokes参数,提供了测量海面风场的一种新方法。首先介绍了国内外先进微波辐射计的技术特点及其海洋遥感应用情况,然后描述了海面微波发射信号的变化机理,以及海面全极化信号的风向谐波特征及其反演海面风场的优势,归纳了全极化微波信号海面风场反演的总体技术思路和产品精度,最后分析了全极化微波辐射计风场反演的关键技术和难点,并对该项技术的发展进行了展望。  相似文献   

12.
A miniaturized inset‐fed on‐body meandered bowtie antenna designed for brain microwave imaging systems is presented in this article. The proposed on‐body antenna can contribute to the realization of a wearable and portable brain microwave imaging system. The size of 18 × 18 mm2 is achieved at a frequency range of 0.75 to 4 GHz by the simultaneous use of self‐complementary structures and meandered lines. The frequency band is a trade‐off between penetration depth and spatial resolution. The proposed antenna performance was studied at different positions on the human head voxel model in terms of several parameters such as reflection coefficient, near‐field directivity, and fidelity factor. In addition, the antenna bandwidth was surveyed on several volunteers using a wearable measurement setup. It has been found that the averages of measured reflection coefficients in different scenarios are in good agreement with the corresponding simulation results, and the antenna shows stable performance under different practical situations. The proposed antenna takes advantage of a small footprint and body matching, which make it an eligible choice for compact, portable, and wearable head microwave imaging systems.  相似文献   

13.
In order to obtain a narrower half power beamwidth (HPBW) and a higher antenna gain in a wide frequency band, metamaterial layers and constant refracting-index lens are used to optimize the antenna performance in this article. The proposed metamaterial covered modified antipodal Vivaldi antenna with lens (M-MAVA with lens) has an operating frequency band of 1–8 GHz, and the maximize gain here is 18.81 dBi at 8 GHz, which increase about 9 dB. The HPBW in the entire frequency range is decreased significantly. Beyond this, the simulation results are in good accordance with the measurements. Based on these characteristics, the proposed M-MAVA with lens has an application in optimizing the structure of ground penetrating radar, microwave imaging, UAV countermeasures system and other system which need the good radiation gain and directivity.  相似文献   

14.
由于卫星与飞机在飞行速度上的巨大差异,收发平台波束足迹的空间同步是星机双基地合成孔径雷达(Spaceborne/Airborne Hybrid Bistatic Synthetic Aperture Radar,SA\|BSAR)的一大技术难点。已经有学者提出了一种基于波束指向控制的同步方法,但该方法存在着成像时间短、算法复杂、方位分辨率低等缺点。提出了一种基于宽波束照射的新方法,对新方法的可行性进行了充分的量化论证和仿真验证。与已有方法相比,所能获得的场景长度略小,但成像时间更长,方位分辨率更高。最后,分析了两种方法的优缺点,明确了各自的适用场合。  相似文献   

15.
A moving target parameter estimation algorithm based on the fractional Fourier transform (FrFT) in combination with along-track interferometry (ATI) was developed previously for airborne (or flat Earth) geometry. Subtle differences exist in migrating from a flat stationary Earth geometry to a spherical rotating Earth geometry. Factors, such as orbital parameters and spacecraft centripetal acceleration, must be taken into account. In addition, the dynamic antenna squint implemented in the RADARSAT-2 satellite for Earth motion compensation needs to be modelled into the algorithm. This paper derives the spaceborne version (i.e. RADARSAT-2) of the algorithm. A simple two-dimensional (2D) signal model is derived and compared to that of three-dimensional (3D) spherical model to warrant its usage, and the FrFT-ATI algorithm is implemented using the derived 2D signal model. Its effectiveness is demonstrated using simulation data.  相似文献   

16.
The concept of imaging spectrometry, or hyperspectral imaging, is becoming increasingly popular in scientific communities in recent years. Hyperspectral imaging data covering the spectral region between 0.4 and 2.5 μm and collected from aircraft and satellite platforms have been used in the study of the earth's atmosphere, land surface, and ocean color properties, as well as on planetary missions. In order to make such quantitative studies, accurate radiometric and spectral calibrations of hyperspectral imaging data are necessary. Calibration coefficients for all detectors in an imaging spectrometer obtained in a laboratory may need to be adjusted when applied to data obtained from an aircraft or a satellite platform. Shifts in channel center wavelengths and changes in spectral resolution may occur when an instrument is airborne or spaceborne due to vibrations, and to changes in instrument temperature and pressure. In this paper, we describe an algorithm for refining spectral calibrations of imaging spectrometer data using observed features in the data itself. The algorithm is based on spectrum-matching of atmospheric water vapor, oxygen, and carbon dioxide bands, and solar Fraunhofer lines. It has been applied to real data sets acquired with airborne and spaceborne imaging spectrometers.  相似文献   

17.
将时域天线组成阵列是改善超宽带雷达技术性能一条行之有效的途径;研究时域天线阵辐射或接收的波形变换和畸变规律.是十分必要的;利用虚拟仪器技术,采用1.abView软件平台,使用模块化设计思想.实现一套慕于示波器和转台协调工作的时域天线阵自动测试系统的设计;通过对灭线阵测试结果进行分析,并与FDTD的仿真结果进行对比,得出关于时域天线阵有价值的结论。  相似文献   

18.
The atmospheric correction microwave radiometer (ACMR) is one of the main payloads for correcting atmospheric path delay in the radar altimeter on the Haiyang-2A (HY-2A) satellite. The ACMR is a three-band microwave radiometer operating at 18.7, 23.8, and 37.0 GHz. Calibration of the ACMR is important for applying its measurements to correct for atmospheric effects on the HY-2A altimeter signal transmission in the air. Therefore, a detailed introduction to the principles and specifications of the ACMR system is given first. The thermal vacuum calibration method of the ACMR is discussed and analysed, and the microwave transfer functions and related coefficients are given, especially the nonlinear coefficients derived from a test for correcting nonlinear responses between the input of antenna temperature and the output of voltage at each channel of the ACMR. Furthermore, antenna pattern correction algorithms for removing the effects of side lobe and cross-polarization are derived and their coefficients are used for in-orbit data processing. Primary calibration results are given by comparing with the similar spaceborne Jason microwave radiometer (JMR) on the Jason-1 satellite and with the advanced microwave radiometer (AMR) on Jason-2. The results of this comparison show that the data from the ACMR match well to those from the JMR and AMR.  相似文献   

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