共查询到18条相似文献，搜索用时 492 毫秒
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基于中频采样的星载合成孔径雷达的数据处理 总被引：1，自引：1，他引：0
研究了基于中频采样的星载合成孔径雷达(synthetic aperture RADAR, SAR)数据处理技术及其FPGA实现. 常规星载SAR系统对模拟解调后的视频数据进行采样,然后对数据进行压缩和格式化处理并下传. 采用中频采样技术实现星载SAR数据的正交解调和处理,对数字正交解调算法和合成孔径雷达BAQ压缩算法进行分析,完成FPGA的硬件设计和仿真. 结果表明,基于FPGA实现星载SAR中频采样的数据处理方法可行. 与传统模拟方法相比,中频采样系统性能和可靠性都有提高,是未来星载SAR数据处理的发展趋势. 相似文献
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提出了一种星载合成孔径雷达(SAR)回波中频采样后直接分块自适应量化(BAQ)的设计.从理论上证明了中频BAQ的可行性.与中频回波数字下变频后再BAQ的典型结构相比,该设计将数字下变频放到地面进行,简化了电路结构,节省了硬件资源.采用免混频结构时,仿真结果表明:下传数据率相同的情况下两者的性能接近,新方案所耗费的硬件资源不到前者的1/3. 相似文献
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利用自主知识产权的DAC IP核设计和电路高速工作的设计技术,研发出硅(Si)基CMOS方式2GHz合成时钟频率的ROM-Less直接数字频率合成芯片.又从原理分析到芯片设计及流片验证完整地研发出融入过采样∑/△技术的新型高分辨率直接数字频率合成芯片.上述工作受到国际同行的重视与好评. 相似文献
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由于缺少SAR散射波干扰真实数据,建立了SAR散射波干扰的物理模型,分析了地面散射点的分布特征,给出了仿真结果.结果表明,对于极度粗糙地表和中等粗糙地表,散射波干扰充斥于SAR的整个波束,不能采用空间滤波的方式进行干扰抑制;对于中等粗糙地表,增加快时间采样点数,可以增加相关散射点的数量,因此可以用空间-快时间自适应滤波的方法提高干扰抑制性能. 相似文献
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建立典型滑动聚束SAR(合成孔径雷达)斜视成像模型.在考虑不同方位目标回波信号多普勒空变性的情况下,详细分析两步算法方位滤波恢复滑动聚束SAR方位欠采样信号的原理.对结合两步算法和传统CS算法的ECS算法进行了在斜视成像模型下的修正.针对滑动聚束工作模式的特点,讨论其中关键处理参数的选择问题,给出算法的处理流程.最后,用计算机仿真实验验证了方法的有效性. 相似文献
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近年来在射频通讯接收机中,低噪声放大器的噪声,增益和线性度直接影响着整个射频前端的性能,因此它成为整个射频前端设计的关键所在。其中,宽带低噪声放大器成为近年来的国内外的研究热点。宽带低噪声放大器主要应用于数字有线电视接收机、数字卫星电视接收机等带宽是中心频率两倍以上的接收机。随着应用越来越广泛,对宽带低噪声放大器的指标要求也越发的苛刻,这就对宽带低噪声放大器的设计提出了新的挑战。本论文正是基于这种现状,通过对参考文献的查阅和研究,对宽带低噪声放大器进行了分析。 相似文献
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针对传统多带宽合成孔径雷达系统需要多个滤波器和多种采样时钟等问题,提出一种新的数字处理方法,并详细介绍了算法方案、仿真结果和基于现场可编程门阵列(FPGA)的算法实现.该方法仅需一个最高频率的采样时钟获取离散化数据,通过对数据的插值得到其他较低时钟频率的数据,而对不同带宽信号的滤波由数字滤波器来实现.这种方法简化了系统设计,提高了系统可靠性. 相似文献
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首先介绍了高压直流开关电源的现状及发展情况,研究了高频开关电源的基本原理,设计出一种实用的高压直流开关电源系统。整个电源系统以89C52单片机作为控制核心,将输出电压,电流采样,经过单片机内由软件编程构成的数字PI调节器处理后控制输出电压的变化。并设计了过压和过流保护功能,应用LED数码管显示输出电压、电流值。 相似文献
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《Journal of The Franklin Institute》2022,359(16):8539-8552
Sampled-data control as an effective mean of digital control has shown its prominent superiority in most practical industries and a zero-order holder (ZOH) is often introduced to maintain continuity of control in the field of sampled-data control system. However, it decreases the control accuracy in a certain extent since the state will be held invariably within each sampling interval. In order to improve the control accuracy, this paper proposes a dynamic model-based control strategy instead of ZOH for a class of switched sampled-data control systems. The model, which is built by abstracting the plant knowledge, is located at the controller side. The controller is set up based on the model state and it provides control input to the switched system. A fixed sampling period is adopted, under which a hybrid-dwell time switching condition is revealed by taking into account asynchronous switching. With reasonable design of switching condition, exponential stability of the closed-loop system can be guaranteed. Finally, advantages of our proposed method are presented through a numerical example by comparing with the result of ZOH-based control. 相似文献
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A new and systematic method to design digital controllers for uncertain chaotic systems with structured uncertainties is presented in this paper. Takagi-Sugeno (TS) fuzzy model is used to model the chaotic dynamic system, while the uncertainties are decomposed such that the uncertain chaotic system can be rewritten as a set of local linear models with an additional disturbed input. Conventional control techniques are utilized to develop the continuous-time controllers first. Then, the digital controllers are obtained as the digital redesign of the continuous-time controllers using the state-matching approach. The performance of the proposed controller design is illustrated through numerical examples. 相似文献
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随着资源的数字化程度不断提高,高校图书馆数字资源建设也得到逐步重视。数字资源的真实利用率一直是图书馆管理者所希望得到的数据之一。而数字资源使用率数据一般由数字资源供应商提供,真实性和准确性有待商榷。由于高校图书馆数字资源使用范围有一定的限制性,借助于这个特点,设计与建设数字资源访问统计系统,提供图书馆数字资源使用的真实信息,为图书馆资源建设提供决策基础。本文从图书馆需求入手,引入系统需求和系统技术原理,同时介绍系统实现案例部分内容,指出数字资源统计系统建设的必要性与存在的难题。 相似文献
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《Journal of The Franklin Institute》2022,359(8):3517-3548
This paper is concerned with the asymptotic stabilization of discrete singular systems over a bandwidth limited digital network, when the state measurements are periodically sampled and encoded using a finite alphabet, and the control input signals are subject to finite-alphabet encoding and Denial-of-Service attacks. It is assumed that the attack signals are uniform for all sampling periods and have been identified. A dynamic controller is designed based on a restricted equivalent model of the controlled plant. Two types of finite-level quantizers are designed for encoding: uniform and logarithmic. For both types of quantizers, dynamic encoding-decoding strategies for the plant state and the control input are proposed, which exploit the controller’s state and the origin, respectively, as the quantization centers. Sufficient conditions for asymptotic stabilizability involving the sampling period, the numbers of the state and input quantization levels, the beginning time and corresponding duration of the attack signals are established by propagating reachable sets during sampling interval. Finally, several numerical examples are given to illustrate the design procedures and the efficacy of the theoretical results. 相似文献
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基于三维重建的分布式卫星SAR干涉测高模型及误差分析 总被引：1，自引：0，他引：1
基于InSAR目标三维重建原理对分布式卫星SAR干涉测高系统模型及工作原理进行了分析,给出了完整的目标位置三维重建闭合形式解;并对影响三维重建精度的主要误差源——基线矢量误差和干涉相位误差进行了详细分析;最后通过仿真分析了基线矢量误差和干涉相位误差特性,从而为系统参量定标及其校正提供了基础. 相似文献