共查询到18条相似文献,搜索用时 218 毫秒
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随着雷达技术的进步和新应用需求的出现,双基地合成孔径雷达(BiSAR)在世界范围内受到了越来越多科技人员的关注,成为国际雷达界的研究热点。该文以BiSAR 实验为脉络,结合BiSAR 系统关键技术突破,从实验系统、处理思路和拓扑几何等方面综合论述了国内外(尤其是欧洲)的研究现状和获取成果,并且详细总结和对比了不同类型BiSAR 成像处理算法,探讨了今后BiSAR 系统的研究思路。 相似文献
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在振动环境下相位噪声对星机BiSAR的影响 总被引:1,自引:0,他引:1
振荡器的相位噪声是影响BiSAR获得高分辨率图像的重要因素之一。振荡器是一种对振动极为敏感的器件。因此,在振动环境下,定量分析相位噪声对BiSAR的影响是十分必要的。文中基于两个独立非同分布的振荡器,机载SAR在静态条件和随机振动环境下,推导了星载一机栽混合BiSAR(SA-BiSAR)积分旁瓣比的计算公式。仿真结果表明,在静态条件下,SA—BiSAR仍然具有很低的相噪谱;机载SAR在振动环境下,对于L波段,可以满足成像的基本要求;对于X波段,需采取必要的隔振措施提高系统的抗振性能来满足成像的条件。 相似文献
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高轨SAR具有覆盖范围广,重访时间短的优势。但是如果采用高轨SAR卫星同时作为发射机和接收机,不能充分发挥高轨SAR的这些优点。采用飞机或低轨卫星作为接收机平台不但能够更灵活地针对目标区域成像,而且分辨率也将大大提高。但是星机双基SAR(BiSAR)的几何构型复杂,难以直观地获知任意几何构型BiSAR的分辨率特性。该文从BiSAR基平面分辨率出发,根据几何构型得到基平面分辨率与地平面分辨率之间的几何关系,解析地表示出了BiSAR在地平面上的分辨率形状。据此可以评估BiSAR系统的分辨力,并且能够通过优化设计系统带宽和合成孔径时间两个参数使得BiSAR系统能够实现更好的分辨率特性。最后,仿真结果验证了方法的有效性。 相似文献
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本文以磁感应成像系统中激励源的设计为例,介绍了利用DSP Builder进行硬件设计的设计思路及方法.文中根据磁感应成像激励源的参数要求,提出了基于直接数字频率合成的多频移相激励源的总体设计方案;说明了利用DSP Builder搭建激励源模型的方法及步骤,最后通过模型仿真,验证了设计激励源模型的可行性. 相似文献
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反射式太赫兹返波振荡器成像系统及其应用 总被引:4,自引:0,他引:4
实现了基于返波管源的太赫兹波反射式成像系统.这是一种新型的无损探伤成像方式.从样品表面或者基底反射回来的太赫兹波被焦热电探测器收集,最后经过计算机处理成像.频率为0.7THz的成像系统被用来对一系列样品进行无损检测,如硬币、徽章、模型飞机以及预埋了人工缺陷的工业样品.结果表明,很多工业材料相对于太赫兹波都是透明的,尤其是一些在航空航天技术中具有广泛应用价值的吸收微波的材料. 相似文献
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双站合成孔径雷达系统同步问题研究 总被引:6,自引:2,他引:4
讨论了双站合成孔径雷达 (双站SAR)收、发系统的同步问题 ,详细分析了频率源稳定性对收发系统间相位同步的影响 ,并给出了计算机仿真结果 相似文献
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Wenqin Wang 《Geoscience and Remote Sensing, IEEE Transactions on》2007,45(9):2695-2700
The use of a novel synchronization link to compensate time, phase, and spatial synchronization errors is proposed, aiming at the development of a practical synchronization technique for bistatic synthetic aperture radar (BiSAR) real-time imaging. With the proposed technique, an amplitude-modulated signal emitting from the transmitter is received by a passive receiver and divided into two channels. One is passed through an envelope detector and then used to trigger the sampling clock, and the second is used to achieve spatial synchronization and phase synchronization. Finally, the residual time synchronization errors are compensated with a proposed high-precision range realignment method, and the residual phase synchronization errors are compensated with autofocus algorithms. This technique allows a passive receiver, which is teamed with an illuminator at a safe standoff distance, to receive the data reflected from potentially hostile areas of interest. Thus, this configuration, making real-time imaging possible, has a particular value in military applications. Simulation results show that successful adaptive synchronization for BiSAR real-time imaging is possible by using this dedicated synchronization link. 相似文献
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In this paper, we propose a simplified spatial channel sounding method by utilizing bistatic synthetic aperture radar (BiSAR) principles. Despite the different deployment geometries compared with a conventional BiSAR system, the feasibility of the approach is established by 1) the proposed method achieves a better spatial resolution than conventional directional channel sounders and 2) reconstruction algorithms based on time-domain back-projection in conjunction with a digital elevation model provide a good imaging performance and are suitable for reconstructing the spatial distribution of scatterers. Simulations of a high-speed rail (HSR) scenario demonstrate that the estimated power delay profiles (PDPs) and power angle profiles (PAPs) are close to the actual values. 相似文献
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Li Ding Yangyang Ye Guoyao Ye Yiming Zhu 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(11):1162-1173
Considering the difficult transceiver-isolation problem of the monostatic synthetic aperture radar (SAR) in the terahertz (THz) band, this paper proposes a compact THz bistatic SAR (BiSAR) geometry. The system allows the separately distributed transmitter and receivers. At the receiving end, there are a direct-wave receiver and an echo receiver, both operating at the heterodyne and in-phase mode. The echo receiver runs along a linear rail to fulfill the scene scanning, while the direct-wave one is fixed as a reference. Furthermore, assuming that the receivers are synchronized, both the problem of synchronization between the separated transmitter and receivers and the problem of timing at the signal acquisition would be solved by utilizing the high coherence between the echo and the direct wave. Based on such a system, the application of THz BiSAR for one-dimensional imaging is taken into consideration. Then, a high-resolution imaging algorithm is proposed benefitting from the total least squares estimating signal parameters via rotational invariance techniques (TLS-ESPRIT) and the spatial smoothing process (SSP). The imaging performance is then demonstrated by both simulations and the experiments in the 0.183 THz. 相似文献
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《Microwave Theory and Techniques》1983,31(10):797-805
Parametric oscillators with a superconducting output cavity are of great interest as sources of very high frequency stability. In this paper, a careful analysis is performed for a parametric oscillator model based on an abrupt junction varactor with fixed-bias voltage and ideal shunt mode operation. Steady-state operation, transfer functions for amplitude and phase fluctuations, and additive noise contributions are examined. An overall estimation of system performance as regards to the phase instabilities shows that although the foreseen characteristics are Iess outstanding than expected from a previously reported analysis, this device compares favorably with the most important available sources based on atomic transitions or on superconducting cavity-stabilized oscillators. 相似文献