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《电子技术与软件工程》2016,(4)
穿墙探测中墙体回波对于目标检测影响较大。针对超宽带穿墙雷达中去除墙体波的问题,提出采用基于EMD方法提取回波信号中的目标信号分量和墙体回波信号分量,并去墙体回波信号。搭建试验系统并通过处理实测数据,结果表明,提出方法能够有效去除墙体回波信号,并且能够保留目标信号的绝大部分信息,进而对运动人体目标进行检测。 相似文献
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海面自身随机多变的特性会对海面目标的雷达回波信号检测产生重要影响。文中利用分形方法对海面建模仿真, 模拟了五种不同的海况,基于雷达工作原理设计了一款雷达视频回波信号仿真软件,提高了仿真的逼真度和实时性。针对雷达散射截面(RCS)不同的舰船目标模拟仿真雷达回波,研究了海况对海面目标雷达回波的影响。结果表明:随海况等级的增加,海杂波噪声信号增强,RCS 相对较小目标的雷达回波会逐渐被海杂波淹没。海面目标雷达回波仿真软件既能用于分析海面及目标的电磁散射特性;同时,在目标检测与识别中会有重要应用价值。 相似文献
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提出了一种改进型的动目标检测(MTD)跟踪目标设计,该方法可根据目标速度实时计算信号周期,保持目标回波始终位于非关断滤波器内,通过参数设计控制目标回波的频谱远离关断滤波器,保证目标回波信号始终被检测到,MTD 处理方法又可实时测量目标的速度,形成闭环的自适应周期MTD 跟踪。该方法在某型雷达上得到应用,性能良好。 相似文献
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针对传统的雷达动目标检测方法在杂波背景下目标识别率低的问题,提出了基于时频分析和卷积神经网络的雷达动目标检测方法。首先,通过同步提取变换将动目标的回波信号转换为时频分布,初步提取回波信号的时频特征;然后,对回波信号时频分布的脊线进行提取,并基于此构建数据集;最后,将数据集输入AlexNet进行训练和测试,实现雷达动目标的识别和分类。仿真实验表明,基于SET和AlexNet的方法在噪声环境下能够有效检测动目标,对匀速、匀减速、匀加速三类动目标都具有较高的识别率。脊线提取的应用增强了低信噪比下回波信号的时频特征,提高了检测方法的准确率和噪声鲁棒性。 相似文献
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光源的光谱特性对高速光纤通信系统的传输特性有很大的影响,本文分析了半导体激光器的相位噪声(线宽)对高速光纤通信系统特性的影响,分析结果指出,在高速长距离IM/DD系统的设计与分析中必须考虑激光器线宽的影响,由于光纤的色散特性,激光器的相位噪声在接收端将转化为强度噪声,使光接收机的接收灵敏度产生恶化,并在BER-Pr曲线上表现出“饱和”现象(floor)。本文的实验结果验证了这一点 相似文献
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激光辐射防护与光电对抗技术研究进展 总被引:11,自引:1,他引:10
介绍了国外激光辐射防护与光电对抗技术的研究和发展概况,内容主要包括:传统的激光防护器材、激光防护新技术和新材料、光电传感器和武器装备光学窗口的激光防护、激光辐射综合防护系统、激光防护器材的评价测试、激光对抗与防护措施,并简述了激光辐射防护技术的发展趋势。 相似文献
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Masaaki Sudo Jun Takayanagi Hideyuki Ohtake 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(11):1139-1147
Because optical fiber-based optical systems are generally robust against external interference, they can be used as reliable systems in industrial applications in various fields. This paper describes fiber lasers generating femtosecond pulses that use optical fibers as gain media and optical paths. Additionally, the nondestructive paint multilayer thickness measurement of automotive parts using terahertz waves generated and detected by femtosecond fiber laser systems was conducted. 相似文献
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为了减少和避免激光和微波辐射眼损伤,设计研制了防激光、防微波、激光探测告警为一体的多功能防护镜。该防护镜由特定功能的光学部件和光电子模块组成,包括多功能复合防护镜片、镜架和激光探测报警系统。进行了多功能防护镜复合技术研究和防护性能测试。结果表明,该防护镜在激光波长532nm,1064nm,790nm,840nm的光密度为4.0~7.28;可见光积分透过率为18.7%;微波衰减大于20dB;报警系统在532nm,1064nm和840nm激光波长能提供自动检测和声光报警,报警器的探测灵敏度为10-7/cm2;该防护镜可承受1g质量、300m/s~400m/s速率的钢制球形破片的冲击;防护镜总质量小于200g,该防护镜防护波段宽、对激光和微波的衰减倍率高、防护角大、可见波段透光性好、可分体和组合使用、体积小、重量轻、便于佩戴、适用于个人佩戴防护和光电传感器的防护。在现代光学实验和各种激光与微波作业环境,以及反恐和公共安全中是不可缺少的防护器材。 相似文献
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Ogusu M. Inagaki K. Mizuguchi Y. Ohira T. 《Microwave and Wireless Components Letters, IEEE》2001,11(7):290-292
We demonstrate the fiber transmission of an IF signal at 60 GHz-band using a two-mode injection-locked Fabry-Perot slave laser for fiber radio systems. The IF signal can be generated by the CW modulation of the slave laser without using an optical intensity-modulator. We confirm the fast response of the modulated slave laser and a 77 dB dynamic range for signal modulation against third-order distortion. The IF signals power deviation caused by fiber dispersion is also investigated 相似文献
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Advances in optical technologies, modulation formats, and symbol transmission rates became paramount for today’s agile high spectral efficiency optical networks. Nonetheless, laser phase noise (PN) has played a major impact on the performance of these systems due to the employment of moderate-quality lasers that significantly affect the implementation of high-order modulation schemes starting from existing QPSK and growing to MQAM, \(M=16\), 32, and 64. In this paper, we report an optical dual-polarization (DP) transmitter prototype that digitally emulates the effect of the laser phase noise, according to Wiener process, applied to a different types narrow-linewidth laser sources. This enables the generation of an arbitrary laser linewidth ranging from kilohertz up to tens of megahertz. Our experimental study evaluates the effect of PN on the performance of tracking algorithms commonly implemented on practical coherent receivers. The experimental results show that, for laser linewidth \(\le \)1 MHz, practical filter recovery algorithm succeeds to make appropriate tracking for both DP-QPSK and 16 QAM at 16- and 32-Gbaud system rates. However, for 10 MHz linewidth, correct recovery is possible only for DP-QPSK. 相似文献
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The contemporary semiconductor laser oscillates and radiates power simultaneously in many of the characteristic modes of its cavity, perhaps only a few for the "stripe" laser neat threshold, but hundreds or thousands for power lasers. This article provides a comprehensive theory of the modal characteristics: field structure, polarization, characteristic frequency, radiation pattern, and losses. A new theory is developed for cavities with a nonuniform dielectric. The subject matter is indispensable to understanding or use of the new nonlinear theory of laser processes. Much of it is also relevant to dielectric, optical transmission systems in general 相似文献
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System structures are described that use a centralized optical source for supplying all optical power needs-signal generation and coherent detection. In the configurations described the following benefits occur. Functional systems can be implemented with already demonstrated, and in many cases readily available components. There is no need for local oscillator optical sources and there is no need to stabilize the local oscillators with respect to a remote transmitter frequency to achieve coherent detection. Increases selectivity against other signal frequencies and increased signal-to-noise result from the use of coherent detection. When configured to equalize reference and signal time delay paths, both slow and fast laser source phase and frequency jitter are compensated for. One may therefore efficiently implemented multiple-access frequency division multiplexed networks in which the individual communication bandwidths are small compared to the linewidth of the laser power source 相似文献