共查询到18条相似文献，搜索用时 140 毫秒
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商用WiFi接收模块可以提供比接收无线信号强度指示（received signal strength indication,RSSI）更细粒的信道状态信息（channel state information,CSI）,利用3根天线获取CSI进行方位到达角（angle of arrival,AOA）估计已成为现实。利用正交频分复用技术（orthogonal frequency division multiplexing,OFDM）将2根天线拓展为60个虚拟天线阵,将前向平滑算法拓展到二维前向平滑算法。利用仿真的非相干信号源和相干信号源数据进行实验,结果表明,在只利用2根接收天线的前提下也能实现基于商用WiFi信号的方位角的AOA估计,所提出的2根天线的虚拟天线阵模型和二维前向平滑算法具有有效性和适用性。 相似文献
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随着电子战、信息战在现代军事领域的地位日趋重要,基于外辐射源的定位跟踪方法成为现代雷达领域的研究热点。针对通过单站接收多外辐射源信号获取角度（direction of arrival,DOA）和时差（time difference of arrival,TDOA）信息对运动目标跟踪的问题,首先推导角度和时差的伪线性观测方程,在通过最小二乘（least squares,LS）算法获取初值的条件下,利用传统的卡尔曼滤波算法实现目标的跟踪,该方法称为伪线性卡尔曼滤波（pseudo-liner Kalman filter,PKF）算法。进一步分析观测方程,提出了利用迭代的IPKF（iterative PKF）目标跟踪算法,并推导其克拉美罗下界（Cramer-Rao lower bound,CRLB）。仿真实验分析说明,该IPKF算法的跟踪精度、收敛速度和稳定性均优于传统的扩展卡尔曼滤波（extended Kalman filter,EKF）算法,且迭代次数越多,性能越好,观测误差越小,跟踪误差越接近CRLB。 相似文献
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针对刚体定位同时估计目标的位置和姿态信息的问题，研究了在三维空间中利用单基站进行刚体定位（RBL）的框架.该框架采用单个基站对安装在刚性目标表面的小规模无线传感器信号的波达方向进行测量，并将其与传感器拓扑信息融合，提出了两种用于RBL的最大似然估计算子.利用改进的高斯-牛顿算法对旋转矩阵和平移向量的最大似然估计算子进行优化估计，解算出了目标物体的三维位置和姿态.仿真结果表明，文中提出的最大似然算子可以接近理论克拉美罗下限，并且在收敛成功率和运算成本方面具有较为出色的性能. 相似文献
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GaryF.Hatke 《GPS天线及其抗干扰技术》2002,(4M):32-38
军用GPS系统必须能在敌方干扰时工作。由于附近干扰机和远距离卫星源之间存在巨大的功率差，所以GPS信号的扩频增益对实现抗干扰（A／J）保护能力是不够的。本提出了采用自适应天线调零系统来实现附加的抗干扰（A／J）保护能力，但是目前的系统，如AB－1就不能抑制与安装在飞机上阵列相关的近场多径干扰。本分析了GPS调零时空自适应（STAP）波束形成器的设计，包括STAP处理器对GPS位置计算的影响，该位置通过测量不同卫星信号的到达时差（TDOA）来计算。本提出了两种新疑结构，其性能通过在1：4比例大小的F－16飞机上进行的多次测量来模拟确定。 相似文献
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研究了通过单站接收多个外辐射源信号实现对固定目标定位的问题。首先,联合角度(DOA)和时差(TDOA)信息构建测量误差的概率密度函数。然后利用牛顿迭代法求解得到目标位置估计的最大似然解,迭代初值由最小二乘算法给出。最后通过仿真实验证明了联合角度和时差的定位系统克拉美罗界低于TDOA系统,本文算法估计结果误差接近克拉美罗界,通过几何精度因子图,分析了影响定位精度的主要因素是测量误差和目标的位置。 相似文献
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针对行人航位推算（PDR）定位存在误差累积和地磁指纹不唯一导致的误匹配问题,本文改进了基于粒子滤波的PDR/地磁指纹室内定位方法。在PDR定位过程中利用地图信息控制粒子权重更新,得到较为准确的位置信息后,利用动态时间规整（DTW）算法在PDR推算位置基础上进行快速序列匹配,获取最优位置估计。试验结果表明,融合定位方法有效解决了行人位置穿墙问题,最大定位误差小于1.5 m,53.33%概率定位精度1 m。 相似文献
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一种反演雷达波束内不均匀反射率场的方法 总被引：4，自引：1，他引：3
本文从原始雷达方程出发,提出了一种雷达加密观测方案和退卷积的数据反演方法,以实现雷达天线波束内的反射率不均匀结构信息的提取。反演方法的数值试验表明,此反演方法比常规测量方法在角分辨率方面提高约３倍,对波束内尺度为０．５８－２．０ＨＷ（ＨＷ是天线３ｄＢ波束宽度）的反射率变化有明显的反演能力。观测数据的测量误差对反演质量的影响也进行了计算和分析。本文还讨论了反演方法对雷达观测中的一些技术参数的要求。这些结果对于提高雷达尤其是星载微波主被动遥感器在测量降水量和云中含水量等参数中的精度有重要作用和现实意义。 相似文献
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近年来,近空间受到了越来越广泛的关注。近空间飞行器兼具卫星和航空飞机的优点,能提供类似卫星的宽覆盖、长续航能力和飞机的快速响应能力,这为研究新体制遥感技术创造了条件。基于此,文章提出了一种基于近空间平台的被动双站合成孔径雷达(SAR)成像方法。首先,通过分析近空间被动双站SAR的空间几何模型,建立了其相应的SAR回波信号模型;然后,根据发射机和接收机对成像目标产生的多普勒效应,对近空间被动双站SAR成像的距离分辨率和方位分辨率进行了分析和仿真,并分析了近空间被动双站SAR存在的方位向调频率空变特性。最后,以接收机静止模式为例,对其成像处理进行了仿真。理论分析和仿真实验结果表明,近空间被动双站SAR是一种具有良好应用前景的遥感新技术。 相似文献
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The SeaWinds-on-QuikSCAT (QuikSCAT) and SeaWinds-on-ADEOS-2 (SeaWinds) scatterometers measure the normalized radar backscatter (/spl sigma//sup o/) of the earth's surface. These identical radar sensors are on different spaceborne platforms in similar orbits. QuikSCAT and SeaWinds data are used to infer near-surface wind vectors, polar sea-ice extent, polar-ice melt events, etc. In order to verify the relative calibration of these sensors, a simple cross calibration based on land backscatter measurements is performed. A first-order polynomial model is used to remove the incidence angle dependence of /spl sigma//sup o/ for selected regions of the Amazon rainforest and the Sahara Desert. It is shown that the two sensors are well-calibrated to each other and require no bias corrections. Additionally, evidence of a diurnal cycle in the Amazon rainforest backscatter is given. 相似文献
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Luc K. Jansen R. W. Kersten P. R. Fiedler R. L. 《Geoscience and Remote Sensing Letters, IEEE》2007,4(2):265-268
Traditionally, interfering emitter signatures have been removed through notched filtering in the range (fast-time) dimension. This works well when a narrowband emitter interferes with a wideband radar pulse; however, when the emitter and radar signal bandwidths are comparable, then this approach fails since the noise is distributed throughout the pulse and the image as well. In cases where the interfering signal is localized in the cross range, joint time-frequency methods can often focus this interference signal, thereby transforming the image. In this transformed image, the interferer is the foreground, and the desired synthetic aperture radar image is blurred and now the background. The focused compressed interferer can be analyzed and censored from the transformed image. Back transformation restores the image with the interference removed. This technique has been fully automated and applied to an Electromagnetics Institute Synthetic Aperture Radar (EMISAR) image contaminated by a nonstationary emitter. The cleansed image is virtually free of the emitter interference 相似文献
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Tran N. Girard-Ardhuin F. Ezraty R. Feng H. Femenias P. 《Geoscience and Remote Sensing Letters, IEEE》2009,6(1):77-81
This letter presents the development of a sea ice flag algorithm for the Envisat altimetry mission to detect sea ice corrupted sea surface height data within quality control processing. The algorithm takes advantage of having both passive and active microwave sensors on the same platform with coregistered measurements. Its performances have been evaluated based on collocations between the along-track Envisat data with reference maps built from combination of daily grids of sea ice concentration from SSM/I sensors and backscatter cross section from SeaWinds scatterometer on QuikSCAT satellite. 相似文献
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《International Journal of Digital Earth》2013,6(8):671-687
Remote-sensing data play an important role in extracting information with the help of various sensors having different spectral, spatial and temporal resolutions. Therefore, data fusion, which merges images of different spatial and spectral resolutions, plays an important role in information extraction. This research investigates quality-assessment methods of multisensor (synthetic aperture radar [SAR] and optical) data fusion. In the analysis, three SAR data-sets from different sensors (RADARSAT-1, ALOS-PALSAR and ENVISAT-ASAR) and optical data from SPOT-2 were used. Although the PALSAR and the RADARSAT-1 images have the same resolutions and polarisations, images are gathered in different frequencies (L and C bands, respectively). The ASAR sensor also has C-band radar, but with lower (25 m) resolution. Since the frequency is a key factor for penetration depth, it is thought that the use of different SAR data might give interesting results as an output. This study describes a comparative study of multisensor fusion methods, namely the intensity-hue-saturation, Ehlers, and Brovey techniques, by using different statistical analysis techniques, namely the bias of mean, correlation coefficient, standard deviation difference and universal image quality index methods. The results reveal that Ehlers' method is superior to the others in terms of spectral and statistical fidelity. 相似文献