共查询到18条相似文献,搜索用时 46 毫秒
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深入分析探地雷达工作原理以及雷达回波信号的特点,采用基于等效时间取样技术实现探地雷达回波信号的数据采集:采用高精度的数字可编程延时器产生稳定的步进时钟,作为时序步进采样的同步信号,同时采用"PC机+单片机+CPLD"以实现对数据采集、存储和传输的时钟控制.较之以前采用模拟电路技术产生步进采样脉冲,有电路简单、精度高、稳定性好和实时性强等优点.将标准的正弦波通过该采集电路,经处理得到恢复的波形,通过波形对比的方式来验证该设计的性能,从而定性的可以看出该设计能良好的恢复原来的信号,满足设计要求. 相似文献
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深入分析探地雷达工作原理以及雷达回波信号的特点,采用基于等效时间取样技术实现探地雷达回波信号的数据采集:采用高精度的数字可编程延时器产生稳定的步进时钟,作为时序步进采样的同步信号,同时采用“PC机+单片机+CPLD”以实现对数据采集、存储和传输的时钟控制。较之以前采用模拟电路技术产生步进采样脉冲,有电路简单、精度高、稳定性好和实时性强等优点。将标准的正弦波通过该采集电路,经处理得到恢复的波形,通过波形对比的方式来验证该设计的性能,从而定性的可以看出该设计能良好的恢复原来的信号,满足设计要求。 相似文献
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由于冲激脉冲探地雷达平均功率低,限制了其作用距离和探测深度,多用于近地表和浅低层探测。为了提高系统的作用距离和探测深度,常采用频率步进探地雷达。利用频率步进信号的大带宽和高平均功率的特点,不但可以提高作用距离和探测深度,而且成像分辨率可以大为改善。由于介质与空气的介电特性不一致,电磁波的传播路径和传播速度会发生相应的改变,常用的回波模型和合成孔径成像方法不再使用。本文推导出了频率步进探地雷达的回波信号模型,并结合SAR成像理论,针对地下目标探测的特点,提出了分层聚焦的SAR成像处理方法,取得了良好的效果。 相似文献
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Gader P.D. Mystkowski M. Yunxin Zhao 《Geoscience and Remote Sensing, IEEE Transactions on》2001,39(6):1231-1244
Novel, general methods for detecting landmine signatures in ground penetrating radar (GPR) using hidden Markov models (HMMs) are proposed and evaluated. The methods are evaluated on real data collected by a GPR mounted on a moving vehicle at three different geographical locations. A large library of digital GPR signatures of both landmines and clutter/background was constructed and used for training. Simple, but effective, observation vector representations are constructed to naturally model the time-varying signatures produced by the interaction of the GPR and the landmines as the vehicle moves. The number and definition of the states of the HMMs are based on qualitative signature models. The model parameters are optimized using the Baum-Welch algorithm. The models were trained on landmine and background/clutter signatures from one geographical location and successfully tested at two different locations. The data used in the test were acquired from over 6000 m2 of simulated dirt and gravel roads, and also off-road conditions. These data contained approximately 300 landmine signatures, over half of which were plastic-cased or completely nonmetal 相似文献
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Single-reference near-field calibration procedure for step-frequency ground penetrating radar 总被引:1,自引:0,他引:1
The antenna system of ground penetrating radar is usually positioned in the vicinity of the ground surface to obtain sufficient spatial resolution for detecting small targets. Therefore, received signals are subject to errors caused by unwanted reflections and coupling. A near-field calibration procedure taking into account these effects as well as antenna dispersion is presented. For practical convenience, only a metal plane is used here as a calibration standard. Calibration data are measured for a set of distances between the antenna and metal plane. The reference reflections in all positions are computed using polynomial representation of the reflected signal. Then, error coefficients are obtained by a solution of a linear system of equations in the least squares sense. Experimental verification of the proposed calibration technique demonstrated efficient removal of artefacts caused by unwanted reflections. Moreover, peaks in the radar range profile become sharper after calibration if the antenna is dispersive. Consequently, the ground response in the form of an exponential term can be effectively subtracted from the received signal. This helps to reveal and discriminate shallow underground targets obscured by strong reflection of the ground surface. Experimental examples are given to illustrate the performance of the method. 相似文献
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