A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domai...A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrationM signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analy- sis and time-frequency analysis.展开更多
通过对2013年6月6日20时-7日20时北京地区出现的中到大雨、局地暴雨的天气过程的大尺度天气环流背景、物理量场、北京多普勒雷达产品和海淀风廓线探测数据、VDRAS反演物理量等多种资料详细分析,得出如下结论：1）本次过程500 h Pa北京...通过对2013年6月6日20时-7日20时北京地区出现的中到大雨、局地暴雨的天气过程的大尺度天气环流背景、物理量场、北京多普勒雷达产品和海淀风廓线探测数据、VDRAS反演物理量等多种资料详细分析,得出如下结论：1）本次过程500 h Pa北京处于从河套以东至长江中下游地区的低槽槽前,温度槽落后于高度槽,地面处于东高西低的形势场中。2）北京处于850 h Paθ（se）高能舌的前部,为对流性天气的出现提供了良好的能量条件。3）强回波在单点稳定少动或多个降水云团先后经过同一地区,造成该地区降水偏大。4）超低空急流加强,且风向由东南转为偏南,南风分量明显加大,有利于水汽的输送和辐合,有利于出现短时强降水。5）据VDRAS反演物理量场的分析,某地区较长时间处于扰动温度相对大值区（0.9-1.2℃）,与该区域降水较大相对应。强回波的合并与维持和其位于东南风和偏南风的辐合区中相关联。6）对EC、T639数值模式降水预报的检验表明,数值模式对明显大尺度系统影响的降水过程预报效果较好,EC对本次过程的预报能力优于T639。展开更多
针对伪随机(PN)码调制的多普勒激光雷达中固有的对外差信号不能等间隔采样的问题,提出一种新的非均匀采样信号的离散傅里叶变换(DFT)方法。首先,给出距离速度同步测量多普勒激光雷达系统模型,指出对外差信号不能等间隔采样的原因;然后,...针对伪随机(PN)码调制的多普勒激光雷达中固有的对外差信号不能等间隔采样的问题,提出一种新的非均匀采样信号的离散傅里叶变换(DFT)方法。首先,给出距离速度同步测量多普勒激光雷达系统模型,指出对外差信号不能等间隔采样的原因;然后,通过理论推导,提出一种新的非均匀采样信号的频谱分析方法;最后,通过仿真验证该方法可用于分析非等间隔采样信号的频谱。结果表明,在道路运动目标产生的多普勒频率范围内,接收信号信噪比(SNR)为0 d B的情况下,该方法仍可有效分析出不等间隔采样多普勒信号的频率。展开更多
文摘A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrationM signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analy- sis and time-frequency analysis.
文摘通过对2013年6月6日20时-7日20时北京地区出现的中到大雨、局地暴雨的天气过程的大尺度天气环流背景、物理量场、北京多普勒雷达产品和海淀风廓线探测数据、VDRAS反演物理量等多种资料详细分析,得出如下结论：1）本次过程500 h Pa北京处于从河套以东至长江中下游地区的低槽槽前,温度槽落后于高度槽,地面处于东高西低的形势场中。2）北京处于850 h Paθ（se）高能舌的前部,为对流性天气的出现提供了良好的能量条件。3）强回波在单点稳定少动或多个降水云团先后经过同一地区,造成该地区降水偏大。4）超低空急流加强,且风向由东南转为偏南,南风分量明显加大,有利于水汽的输送和辐合,有利于出现短时强降水。5）据VDRAS反演物理量场的分析,某地区较长时间处于扰动温度相对大值区（0.9-1.2℃）,与该区域降水较大相对应。强回波的合并与维持和其位于东南风和偏南风的辐合区中相关联。6）对EC、T639数值模式降水预报的检验表明,数值模式对明显大尺度系统影响的降水过程预报效果较好,EC对本次过程的预报能力优于T639。
文摘针对伪随机(PN)码调制的多普勒激光雷达中固有的对外差信号不能等间隔采样的问题,提出一种新的非均匀采样信号的离散傅里叶变换(DFT)方法。首先,给出距离速度同步测量多普勒激光雷达系统模型,指出对外差信号不能等间隔采样的原因;然后,通过理论推导,提出一种新的非均匀采样信号的频谱分析方法;最后,通过仿真验证该方法可用于分析非等间隔采样信号的频谱。结果表明,在道路运动目标产生的多普勒频率范围内,接收信号信噪比(SNR)为0 d B的情况下,该方法仍可有效分析出不等间隔采样多普勒信号的频率。
