为提高小目标识别性能,多波束测深仪通常使用短连续脉宽信号(Continuous Wave,CW)进行探测。然而,短脉宽信号携带能量有限,测深最大距离及扫测宽度得不到保证。发射长脉宽线性调频(Linear Frequency Modulation,LFM)信号,结合脉冲压缩...
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为提高小目标识别性能,多波束测深仪通常使用短连续脉宽信号(Continuous Wave,CW)进行探测。然而,短脉宽信号携带能量有限,测深最大距离及扫测宽度得不到保证。发射长脉宽线性调频(Linear Frequency Modulation,LFM)信号,结合脉冲压缩技术可解决这一矛盾。本文主要介绍LFM信号在国产iBeam8120浅水多波束测深仪中的工程应用情况,重点阐述接收回波信号处理方法,实测数据脉冲压缩效果,并分析了相位差精度影响因素。外场试验数据表明:经脉压处理后,声呐图回波能量更为集中,底检测性能得到改善。
Effective prediction of crop pest species and quantities can provide a priori knowledge for pest control. However, there are many kinds of pests and the color and texture of different pests are similar, traditional im...
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Moving target detection algorithm plays a vital role in computer vision research. Moving object detection mainly processes video images to identify moving objects differently from the background. Moving target detecti...
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Moving target monitoring is widely used in many fields such as industrial control, military, and security. Traditional moving target monitoring generally uses infrared, ultra-sonic and other technologies, which have t...
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Non-contact medical monitoring is an emerging challenging field. In this paper, based on the single chip radar development kit of XeThru X4 ultra wideband (UWB) modules, a small radar system is systematically designed...
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ISBN:
(纸本)9781665468893
Non-contact medical monitoring is an emerging challenging field. In this paper, based on the single chip radar development kit of XeThru X4 ultra wideband (UWB) modules, a small radar system is systematically designed for indoor human body tracking, and fall detection. The algorithms are compared, optimized, and integrated in the system. In signalprocessing, moving target indication (MTI) and clutter map methods are employed to cancel strong fixed clutter; wavelet analysis is used to denoise and reconstruct the echoes of human breathing and heart-movement; center-of-gravity ranging method is used to detect the presence of human targets and to measure the human range. In dataprocessing, using only the range dimensional measurement, the algorithms for single human target track initialization, track filtering, data association, and track management are designed in a systematic way. Since a normal human body is usually stationary or moving uniformly, a constant-velocity (CV) model is adequately to estimate the human state, and the normalized innovation squared (NIS) is sliding averaged to implement fall judgment. The field data show that the system can effectively detect and track a human body, make timely judgments of human falling and drastic moving changes of state, and extract other vital features.
Distributed radar array brings several new forthcoming advantages in aerospace target detection and imaging. The two-dimensional distributed array avoids the imperfect motion compensation in coherent processing along ...
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Distributed radar array brings several new forthcoming advantages in aerospace target detection and imaging. The two-dimensional distributed array avoids the imperfect motion compensation in coherent processing along slow time and can achieve single snapshot 3D imaging. Some difficulties exist in the 3D imaging processing. The first one is that the distributed array may be only in small amount. This means that the sampling does not meet the Nyquist sample theorem. The second one refers to echoes of objects in the same beam that will be mixed together, which makes sparse optimization dictionary too long for it to bring the huge computation burden in the imaging process. In this paper, we propose an innovative method on 3D imaging of the aerospace targets in the wide airspace with sparse radar array. Firstly, the case of multiple targets is not suitable to be processed uniformly in the imaging process. A 3D Hough transform is proposed based on the range profiles plane difference, which can detect and separate the echoes of different targets. Secondly, in the subsequent imaging process, considering the non-uniform sparse sampling of the distributed array in space, the migration through range cell (MTRC)-tolerated imaging method is proposed to process the signal of the two-dimensional sparse array. The uniformized method combining compressed sensing (CS) imaging in the azimuth direction and matched filtering in the range direction can realize the 3D imaging effectively. Before imaging in the azimuth direction, interpolation in the range direction is carried out. The main contributions of the proposed method are: (1) echo separation based on 3D transform avoids the huge amount of computation of direct sparse optimization imaging of three-dimensional data, and ensures the realizability of the algorithm;and (2) uniformized sparse solving imaging is proposed, which can remove the difficulty cause by MTRC. Simulation experiments verified the effectiveness and feasibility of
Ground penetrating radar (GPR) is one of the most commonly used technologies for non-destructive testing (NDT). With the development of GPR signalprocessing methodologies, researchers are becoming more concerned not ...
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ISBN:
(数字)9781665422536
ISBN:
(纸本)9781665446624
Ground penetrating radar (GPR) is one of the most commonly used technologies for non-destructive testing (NDT). With the development of GPR signalprocessing methodologies, researchers are becoming more concerned not just with the detection of the target itself, but also with their physical properties and main features. In general, full waveform inversion algorithm is required to achieve this aim. But, full waveform inversion problem is a costive approach which need a huge computation. Thus, the ultimate goal of this study is to explore an effective strategy for estimating the relative permittivity of the target using polarimetric GPR data. We have investigated the relation between relative permittivity and polarimetric alpha angle based on the data collected by dualpolarization antennas GPR system. Laboratory experiments that measures different moisture sand targets (simulating for different relative permittivity target) in tree trunk holes have been carried out, taken as analog models for the physiological process representing decays in trees. After signalprocessing, the rough results that alpha angle versus with relative permittivity were obtained. The results show that for a dry sand the polarimetric alpha angle is small and the polarimetric alpha angle increases with increasing water content.
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