联合时频分析在相干测风激光雷达中的应用  

Application of joint time-frequency analysis in coherent Doppler wind lidar

作　　者：刘燕平 王冲[1] 吴云斌 上官明佳 夏海云[1] Liu Yanping;Wang Chong;Wu Yunbin;Shangguan Mingjia;Xia Haiyun(School of Earth and Space Science,University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学技术大学地球与空间科学学院,安徽合肥230026

出　　处：《红外与激光工程》2018年第12期73-80,共8页Infrared and Laser Engineering

摘　　要：相干测风激光雷达具有风场测量精度高、高时空分辨率、探测范围广等突出优点,已广泛应用于风切变探测、飞机尾流探测、风力发电和大气湍流探测等方面。如何从大气回波信号中提取微弱的多普勒频移信息是激光雷达信号处理的难点。基于大气分层模型仿真生成相干激光雷达大气回波信号,对模拟回波信号应用不同的时频分布进行时频分析。随后对比了时频分析的效果,自适应最优核时频分布具有运算量小,交叉项抑制效果好,时频聚集度高等优点。最后,使用1.5μm相干多普勒激光雷达于2017年3月份在安徽合肥进行实地观测,将自适应最优核时频分布应用于实测数据,与传统的快速傅里叶方法对比风速反演结果。结果表明:自适应最优核时频分布能更好地反映出风速细节信息,3 km内距离分辨率为1.2 m,3 km后经平滑保持了对远场弱信号风速估计的连续性,时间分辨率为1 s时其最远水平探测范围约在6 km。With high accuracy,high spatial-temporal resolution,large scale coverage,coherent Doppler lidar has been widely applied in the detection of wind shear,aircraft vortex,wind power generation,atmosphere turbulence and so on.For lidar signal processing,the key issue is how to extract weak Doppler frequency shift in the weak backscatter signal.Based on the atmospheric slices model,the simulated echo signal of coherent Doppler lidar was processed by different time-frequency methods.Simulation results show that the adaptive optimal-kernel time frequency representation outperforms the others,having the advantages of lower computation cost,suppressing cross terms efficiently and higher resolution in both time and frequency domains.Then the adaptive optimal-kernel time frequency representation was applied to the field experiment data derived from a1.5μm Coherent Doppler lidar in Hefei,Anhui Province in March,2017.The retrieved wind velocity results were compared with that derived from the fast Fourier transform algorithm.Experimental results show that the range resolution is1.2meter within3kilometers,and maintains the continuity of wind speed retrieved form weak signal using a50-points window in the far field over3kilometers.Furthermore it can track the wind details better and enhance the detection range to6kilometers as the temporal resolution is set to1second.

关 键 词：时频分析 相干测风激光雷达 大气分层模型 

分 类 号：TN958.98[电子电信—信号与信息处理]