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地面测控雷达角度标校技术 总被引:1,自引:0,他引:1
在航天测控领域中,为了准确定轨,需要时航天器运行轨道进行精确地测量,因此对地面测控雷达的测角精度要求很高。本文主要对地面测控雷达的角度标校问题进行了讨论,并时标校误差进行了分析,可以通过准确地角度标校和对标校误差的修正处理提高地面测控雷达的测角精度。 相似文献
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车载雷达角度标校方法 总被引:1,自引:0,他引:1
根据雷达工作过程中的误差来源和性质,对雷达的几种误差进行了简单的分析,总结出了雷达测角误差模型。主要讨论了车栽移动式雷达的几种角度标校方法,针对不同的任务需求,介绍了常规标校、星体标校、借助电子设备自动定北、太阳跟踪标校等方法,并对各种标校误差进行了简单的比较分析。针对车栽雷达机动性强、系统要求快速恢复等特点,提出了一种与天线控制单元相结合的自动标校方法。 相似文献
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采用AE类型天线座的精密测量雷达在角度标校过程中涉及轴系及误差校正参数的定义、术语、标定方法、校正模型及参数符号等在不同文献、不同型号雷达、不同研制单位存在较大差异。针对这一实际情况,本文具体介绍了轴系和标校误差项的概念,明确了各校正误差的校正思路,简单分析了各误差项产生原理,详细阐述了各误差校正参数符号与校正模型的关系。针对两种校正模型提出了对应的误差校正参数的符号约束,避免了由于误差校正参数标定方法及符号装订错误引起测角超差故障。最后分析并给出了自动化标校中各校正参数的简化计算模型。 相似文献
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瞬态极化雷达采用同时发射、同时接收的测量体制,可以利用正交极化通道的单次回波信号测量目标极化散射矩阵。首先给出了窄带瞬态极化雷达信号模型和信号处理方法;然后详细分析了两类瞬态极化雷达信号波形(频移脉冲矢量波形和正负调频斜率LFM矢量波形)的测量性能;最后用国防科技大学研制的X波段瞬态极化雷达系统开展外场实验,实验结果表明:与分时极化测量结果相比,两者的相对幅度测量结果差异小于2 dB,相对相位测量结果差异小于10,°从而验证了瞬时极化测量的有效性。 相似文献
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雷达目标极化散射矩阵测量的新方法研究 总被引:2,自引:2,他引:0
立足现有的单极化雷达,通过充分利用天线极化在空间并非一成不变而是空域指向的函数这一固有属性(简称"天线的空域极化特性"),提出了一种目标极化散射矩阵(PSM)测量的新方法.该方法无需两个极化通道,仅通过利用天线的空域极化特性以及对雷达接收回波进行处理,完成目标的PSM测量.首先分析了均匀矩形口径天线的空域极化特性;在此基础上,通过对天线扫描过程中多个接收回波的空域处理,导出了雷达目标PSM的估计方法,并详细分析了其估计性能;最后进行了计算机仿真,实验结果验证了算法的有效性. 相似文献
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在外场动态RCS测量中,普遍采用自由空间标准金属球对测量系统进行标校,但这种方法只能完成对测量系统同极化的标校,而不能对交叉极化通道进行标校。在对各种标准目标的RCS极化矩阵进行详细分析的基础上,提出了一种新的标校方法,该方法能同时对测量系统的同极化和正交极化通道进行校准。 相似文献
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A general polarimetric radar calibration technique 总被引:5,自引:0,他引:5
Whitt M.W. Ulaby F.T. Polatin P. Liepa V.V. 《Antennas and Propagation, IEEE Transactions on》1991,39(1):62-67
A polarimetric radar calibration procedure is introduced and verified with experimental results. The procedure requires measurements of three known targets in order to determine the distortion matrices that characterize the effect of the measurement system on the transmitted and received waves. The scattering matrices for the known targets can be of any form, provided that a limited set of constraints is satisfied. A special case, wherein the transmit and receive distortion matrices are the transpose of each other, is considered. This case is useful for some single antenna systems and has the advantage that only two known targets are required 相似文献
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A practical technique for calibrating single-antenna polarimetric radar systems is introduced. This technique requires only a single calibration target such as a conducting sphere or a trihedral corner reflector to calibrate the radar system, both in amplitude and phase, for all linear polarization configurations. By using a metal sphere, which is orientation independent, error in calibration measurement is minimized while simultaneously calibrating the crosspolarization channels. The antenna system and two orthogonal channels (in free space) are modeled as a four-port passive network. Upon using the reciprocity relations for the passive network and assuming the crosscoupling terms of the antenna to be equal, the crosstalk factors of the antenna system and the transmit and receive channel imbalances can be obtained from measurement of the backscatter from a metal sphere. For an X -band radar system with cross polarization isolation of 25 dB, comparison of values measured for a sphere and a cylinder with theoretical values shows agreement within 0.4 dB in magnitude and 5° in phase. An effective polarization isolation of 50 dB is achieved using this calibration technique 相似文献
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Sheen D.R. Freeman A. Kasischke E.S. 《Geoscience and Remote Sensing, IEEE Transactions on》1989,27(6):719-731
The problem of phase calibration between polarization channels of an imaging radar is studied. The causes of various types of phase errors due to the radar system architecture and system imperfections are examined. A simple model is introduced to explain the spatial variation in phase error as being due to a displacement between the phase centers of the vertical and horizontal antennas. It is also shown that channel leakage can cause a spatial variation in phase error. Phase calibration using both point and distributed ground targets is discussed and a method for calibrating phase using only distributed target is verified, subject to certain constraints. Experimental measurements using the NADC/ERIM P-3 synthetic-aperture radar (SAR) system and NASA/JPL DC-8 SAR, which operates at C-, L-, and P-bands, are presented. Both of these systems are multifrequency, polarimetric, airborne, SAR systems.<> 相似文献
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Lahtinen J. Hallikainen M.T. 《Geoscience and Remote Sensing, IEEE Transactions on》2003,41(3):603-611
This paper describes the Helsinki University of Technology's Fully Polarimetric Calibration Standard (FPCS). The developed standard generates a complete Stokes reference vector and it is applied for the end-to-end absolute calibration of a fully polarimetric microwave radiometer at 36.5 GHz. The FPCS is based on the function principle of a Gasiewski-Kunkee linearly polarized (tripolarimetric) standard, with an additional phase retardation plate to generate the fourth Stokes parameter. Design considerations and operational aspects of the standard are discussed in this paper. An advanced calibration procedure, which takes advantage of both the tripolarimetric and fully polarimetric calibration scenes to suppress calibration uncertainties, is introduced. The feasibility of the standard has been verified and the generated brightness temperatures in a sample calibration are presented. An extensive set of tests has been performed to evaluate the characteristics and performance of the calibration standard. Furthermore, the use of the advanced calibration procedure to measure the characteristics of the phase retardation plate has been successfully demonstrated. The achievable calibration accuracy is analyzed and discussed relative to requirements for maritime wind vector measurements; the results indicate that the pixel-to-pixel retrieval of the wind speed is possible with high accuracy and the retrieval of the wind direction with at least moderate accuracy. In addition to calibration of a fully polarimetric radiometer, other potential applications, e.g., linearity measurements, are discussed. 相似文献
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Lahtinen J. Gasiewski A.J. Klein M. Corbella I.S. 《Geoscience and Remote Sensing, IEEE Transactions on》2003,41(3):588-602
A technique for absolute end-to-end calibration of a fully polarimetric microwave radiometer is presented. The technique is based on the tripolarimetric calibration technique of Gasiewski and Kunkee, but is extended to provide a means of calibrating all four Stokes parameters. The extension is facilitated using a biaxial phase-retarding microwave plate to provide a precisely known fourth Stokes signal from the Gasiewski-Kunkee (GK) linearly polarized standard. The relations needed to determine the Stokes vector produced by the augmented standard are presented, and the effects of nonidealities in the various components are discussed. The application of the extended standard to determining the complete set of radiometer constants (the calibration matrix elements) for the National Oceanic and Atmospheric Administration Polarimetric Scanning Radiometer in a laboratory environment is illustrated. A calibration matrix inversion technique and error analysis are described, as well. The uncertainties associated with practical implementation of the fully polarimetric standard for spaceborne wind vector measurements are discussed relative to error thresholds anticipated for wind vector retrieval from the U.S. National Polar-Orbiting Environmental Satellite System. 相似文献
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Nashashibi A. Sarabandi K. Ulaby F.T. 《Antennas and Propagation, IEEE Transactions on》1995,43(4):396-404
A new technique for calibrating a coherent-on-receive polarimetric radar system is proposed. A coherent-on-receive polarimetric radar is capable of measuring the Mueller matrix of point or distributed targets directly by transmitting at least four independent polarizations and measuring the vertical and horizontal components of the backscatter signal simultaneously. The technique requires the use of two calibration targets, a target with known scattering matrix (such as a metallic sphere or a trihedral corner reflector) and any depolarizing target (for which knowledge of its scattering matrix is not required) to determine the system distortion parameters. The system distortion parameters, which include the channel imbalances, the cross-talk factors of both the transmit and the receive antennas, and the phase shifts and amplitude variations of the transmitter polarizers, are determined by measuring the calibration targets for four different transmit polarizations. The validity of the new calibration technique is examined by measuring the scattering matrices of spheres and cylinders as test targets using a coherent-on-receive radar operating at 34.5 GHz. Excellent agreement between the theoretical and the measured scattering matrices for the test targets are obtained 相似文献
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Full polarimetric calibration for radar cross-section measurements: performance analysis 总被引:3,自引:0,他引:3
Welsh B.M. Kent B.M. Buterbaugh A.L. 《Antennas and Propagation, IEEE Transactions on》2004,52(9):2357-2365
Full polarimetric scattering measurements are increasingly required for radar cross-section (RCS) tests. Conventional calibration fails to take into account the small amount of antenna cross-polarization coupling that will be present for any practical antenna. In contrast, full polarimetric calibration takes into account and compensates for the nonideal couplings in the transmit and receive channels and paths. We use an existing full polarimetric calibration procedure and a simulation-based performance to study how well the procedure improves measurement accuracy over conventional calibration under practical measurement conditions. 相似文献
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The cetp and Thomson- csf have developed in 1992 a new polarimetric fm/cw X- band radar which has been designed to be easily mounted on small helicopter or aircraft. As it is devoted to research investigations on radar polarimetry applied to land and vegetation remote sensing, it needs to be calibrated in phase and amplitude with a very good accuracy. A calibration procedure using trihedral and dihedral corner reflectors is presented here and then compared to the calibration method using random distributed targets that has been developed at the Jet Propulsion Laboratory. A very good agreement between both methods enables us to apply our calibration algorithms to natural surfaces measurements at different incidence angles (20°, 40° and 50°. 相似文献
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首先基于IPIX分时全极化雷达的海杂波实测数据,分析了瑞利分布、韦布尔分布、对数正态分布和K分布对实测数据的拟合效果,发现对数正态分布拟合水平极化接收通道的杂波数据效果较好,K分布拟合垂直极化接收通道的杂波数据效果较好,但是仍然存在海杂波"拖尾"区域拟合不理想的情况.为此,假设海杂波中的布拉格散射体的回波服从K分布,离散海尖峰的回波服从对数正态分布,海杂波整体服从K分布和对数正态分布的叠加混合分布,提出了一种具有闭式表达式的混合分布,以改善海杂波分布"拖尾"部分的拟合效果.实测数据分析表明,本文提出的混合分布对海杂波幅度分布的拟合效果优于对数正态分布和K分布. 相似文献