调频连续波相干激光雷达的多脉冲频域相干累积研究  

Multi-Pulse Coherent Accumulation in Frequency Domain Based on Frequency-Modulation Continuous-Wave Coherent Lidar

作　　者：从海胜 孙建锋[1] 卢智勇[1] 贺红雨[1,2] 韩荣磊 任伟杰 张龙坤 姜玉鑫 李超洋 Cong Haisheng;Sun Jianfeng;Lu Zhiyong;He Hongyu;Han Ronglei;Ren Weijie;Zhang Longkun;Jiang Yuxin;Li Chaoyang(Key Laboratory of Space Laser Communication and Detection Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academic of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所空间激光信息传输与探测技术重点实验室,上海201800 [2]中国科学院大学,北京100049

出　　处：《中国激光》2022年第3期137-151,共15页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFB0408302);国家自然科学基金(91938302)。

摘　　要：针对相干激光雷达在低空、远距离、高动态目标探测等应用场景中存在的弱信号探测问题,基于调频连续波相干激光雷达,采用多脉冲频域相干累积方法提高激光雷达弱回波信号的信噪比。结合调频连续波理论,分析了信号幅度起伏和相位起伏对多脉冲频域相干累积信噪比效果的影响,实验结果表明,经过M脉冲周期的频域相干累积,微弱回波信号对数信噪比可提升10lg M dB,并且信号幅度起伏、相位起伏可导致多脉冲相干累积信噪比低于理想相干累积信噪比,对于均值分别为2.25×10^(-4)、1.65×10^(-4)和相对起伏幅度分别为0.69、0.93的回波信号而言,相位补偿后的回波信号在50脉冲周期内相干累积信噪比的误差因子最大为0.57%、0.3%,该多脉冲频域相干累积方法对相干激光雷达在远距离目标探测、微弱信号接收方面的应用具有重要意义。Objective When coherent lidar detects a target at a long distance,the laser beam is affected by atmospheric absorption,scattering,turbulence,diffuse scattering of target and nonideal detection.Consequently,the noise exceeds the signal,severely influencing the detection ability for long-range targets.For the weak signal of low-speed moving targets,coherent lidar usually uses the pulse coherent accumulation method and can receive lower-signal power,which greatly improves its sensitivity.Range and doppler migrations easily occur in the coherent accumulation of high-speed manoeuvring targets,resulting in phase inconsistency of the echo signal,energy dispersion in the frequency domain,and limited coherence accumulation time,which affects the multi-pulse coherent accumulation.In this case,microwave radars use Hough transform,sequence shift gene algorithm,acceleration blind estimation to achieve long-time coherent accumulation of the echo signals of high-speed moving targets.Noncoherent lidar achieves coherent accumulation of multiple pulses for high-speed moving targets using pulse shift and time-resolution reduction.Meanwhile,the range resolution of the system is also reduced.However,the processing method for the weak signals of high-speed moving targets using coherent lidar has not been reported.Improving the detection performance of high dynamic targets in long-distance and high-dynamic targets is a challenge.In addition,the amplitude and phase fluctuations of the signals considerably affect multi-pulse coherent accumulation;thus,investigating their effects is necessary.Methods The theory of multi-pulse coherent accumulation in frequency domains based on frequency modulation continuous wave(FMCW)coherent lidar was confirmed through a laboratory verification experiment.The experiment was conducted through the following steps.First,fast Fourier transform and multi-pulse non-coherent accumulation were used to find the signal frequency point.Then,the phase of the signal frequency point in each pulse was extracted,and ph

关 键 词：遥感 调频连续波 多脉冲频域相干累积 动态目标 弱信号探测 相干激光雷达 幅度相位起伏 

分 类 号：TN958.98[电子电信—信号与信息处理]