外差探测随机相位调制连续波激光测距的快速解调方法  

Computation Efficient Demodulation Method for Random Phase Modulated Continuous Wave Light Ranging Based on Heterodyne Detection

作　　者：吴映 邓力华 马超峰 梁伟 WU Ying;DENG Lihua;MA Chaofeng;LIANG Wei(Suzhou Institute of Nano-tech and Nano-bionics,Chinese Academy of Sciences,Suzhou 215123,China)

机构地区：[1]中国科学院苏州纳米技术与纳米仿生研究所,苏州215123

出　　处：《光子学报》2023年第8期165-171,共7页Acta Photonica Sinica

基　　金：国家自然科学基金(No.62075233);中国科学院稳定支持基础研究领域青年团队计划(No.YSBR-69);江苏省卓越博士后计划。

摘　　要：基于外差相干检测的随机相位调制连续波激光测距具有灵敏度高、对背景噪声容忍度高等优点,但传统的解调方法都是基于序列移位相乘和傅里叶变换,需要消耗大量计算资源和计算时间。提出并验证了一种针对随机相位调制连续波激光测距的快速解调方法,通过对回波外差信号进行傅里叶变换得到多普勒频移,解调出目标速度信息,然后通过数字下变频获得回波信号的正交分量,最后利用傅里叶变换在频域实现伪随机调制序列与回波信号的循环卷积,得到目标的位置信息。在原理验证实验中,使用长度为2 047的11阶伪随机二进制序列,调制速率为40 MHz,利用快速解调方法从回波信号中成功恢复了目标位置和速度,并在光纤中实现了2.7 m的距离分辨率。Light Detection and Ranging(LiDAR) is a powerful ranging tool.Various types of LiDARs are widely used in atmospheric and oceanic sciences,such as laser altimeters,deep space exploration,and underwater target detection,most of which are based on time-of-flight.The integrated echo energy of pulsed LiDAR is inversely proportional to the square of detection distance.In order to achieve a longer detection distance,a pulse laser with high peak power is required.The longer the detection distance,the higher the peak power required.In order to achieve high peak power,complex and bulky lasers are usually needed.Meanwhile,the repetition rate of the laser is limited by the thermal damage threshold,which will reduce the point frequency of laser ranging.In order to achieve long detection distances with a low peak power lasers,some researchers have proposed a random code modulation continuous wave technology,which transmits a continuous laser with random pulse modulation instead of a single pulse.The distance information is obtained by cross-correlating the echo signal and the random modulation signal.Compared with a single pulse,the equivalent duty cycle of random code modulation is higher,so the peak power of the light source required to achieve the same integral energy is lower.It is possible to use miniaturized semiconductor lasers to achieve long-distance detection.In addition to using random intensity modulation for ranging,a random phase modulation laser ranging system based on heterodyne coherent detection has also been proposed.Heterodyne coherent detection can greatly improve the ranging sensitivity.More importantly,the target speed can be directly demodulated by measuring the Doppler frequency shift.However,the cross-correlation algorithm used for direct adjustment and detection of random intensity modulated laser ranging can not be directly transplanted to random phase modulated laser ranging system.A common solution is to sequentially shift the transmitted random sequence and multiply it with the echo heterodyne si

关 键 词：激光测距 相位调制 相干探测 伪随机码 

分 类 号：TN247[电子电信—物理电子学]