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Recently the investigation of non-stationary systems exhibiting spatial and dynamic heterogeneities has propelled the development of innovative optical techniques providing the missing link between the scattering and imaging approaches. The novel techniques are characterized by the fact that the scattered radiation is measured close to the sample. They allow to recover information on the structure and dynamics of the system under investigation equivalent to that available with scattering techniques, with the great advantage that they simultaneously allow to achieve a local characterization of the sample, which is lost in traditional scattering measurements. 相似文献
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Frequency-hopped spread-spectrum systems (FHSS) traditionally employ a super-heterodyne receiver architecture to perform frequency hopping in the passband. Such an architecture consists of analog blocks such as the mixer and the local oscillator that contribute greatly to the overall cost and hardware complexity of the system. The recent development of direct radio-frequency (RF) data converters has led to the possibility of having an all-digital receiver architecture where an RF signal is digitized directly to baseband, without the need to translate it to an intermediate frequency. Motivated by this, we propose an all-digital wideband frequency-hopped orthogonal frequency division multiplexing system which is abbreviated as Digi-FH-OFDM in this paper. The system performs two-stage frequency hopping — one in the wideband and the other in the baseband. The system architecture and the implementation details are presented. Real-time power spectra of the hopped signals in the wideband are obtained after transmitting them over the air via the RF data converters of the reconfigurable Xilinx Ultrascale ZCU111 RFSoC board and the Qorvo RF front end card. The bit error rate performance of the system is studied against eavesdropping and jamming attacks under a slow-fading channel and pilot-based channel estimation. The proposed Digi-FH-OFDM system outperforms the existing analog and partially digital FH-OFDM systems in terms of hardware complexity, robustness to eavesdropping and jamming, and the overall latency. 相似文献
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远程警戒雷达由于作用距离远、发射功率大、优良的抗干扰性能的特点,主要用于搜索、监视空中或海上目标,并可引导我方战斗机执行任务,而受到各军事强国的重视并大力研发。在对此类雷达的超视距侦察和干扰方面,国内外鲜有工程实现和文献著述。本文通过对超视距侦察和干扰技术的研究,寻找出一种新的地对地干扰方案。该方案对干扰和破坏敌方雷达侦察我方目标,并能掩护我方目标,同时也能检验我方雷达的抗干扰能力。 相似文献
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本文首先介绍了变频器的干扰来源,然后分析了干扰的传播方式,最后给出了隔离干扰、设置滤波器、屏蔽干扰源、正确接地、采用电抗器和合理布线等六种变频调速系统的抗干扰对策。 相似文献
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张成伟 《电子信息对抗技术》2002,17(6):16-19
现代新体制雷达的不断涌现 ,对ECM干扰源提出了新的要求。运用直接数字合成器(DDS)设计一种新型干扰源 ,通过对新型干扰源的分析 ,阐明了新型干扰源在系统中的使用方法及应用前景 相似文献
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电磁兼容性设计在电子产品中的应用 总被引:3,自引:1,他引:3
本文从电磁兼容性设计的特点出发,结合电磁兼容性设计的内容,对干扰源的抑制、电场屏蔽、磁场屏蔽、滤波、接地、搭接、布局与线缆敷设的方法和注意事项进行了阐述. 相似文献
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在分析测控系统抗干扰薄弱环节的基础上论述了测控链路干扰防护的重点,提出了几种测控链路干扰防护措施,包括能量干扰防护、信号干扰防护和信息干扰防护等. 相似文献
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现代战争中,超视距打击已经成为一种重要的作战手段。为了延长预警时间并有效地干扰视距以外的电子目标,超视距电子对抗系统便成为未来军事斗争中的重要电子战装备。本文对地波绕射超视距短波通信对抗系统的可行性进行了论证。结果表明,该系统对海上(300~400km范围内)短波通信装备的侦察、干扰是可行的。 相似文献