光学多普勒差分流速仪数据解调方法验证  

Verification of demodulation method for differential optical Doppler velocimetry data

作　　者：张治军[1] 宋冉 蒋莉莉 张欣雨 李冰冰 陈胜功 苏娟 吴锜 Zhang Zhijun;Song Ran;Jiang Lili;Zhang Xinyu;Li Bingbing;Chen Shenggong;Su Juan;Wu Chi(Institute of Marine Science and Technology,Shandong University,Qingdao 266237,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;Qingdao Institute of Marine Sensors,Qingdao 266237,China;Aixsensor Co.Ltd.,Dezhou 253084,China)

机构地区：[1]山东大学海洋研究院,山东青岛266237 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458 [3]青岛海洋传感器产业技术研究院,山东青岛266237 [4]德州尧鼎光电科技有限公司,山东德州253084

出　　处：《红外与激光工程》2024年第4期276-280,共5页Infrared and Laser Engineering

基　　金：南方海洋科学与工程广东省实验室(广州)基金项目(GML2021GD0808)。

摘　　要：光学多普勒差分流速仪在测量海水流速时,由于信号微弱和噪声干扰,接收信号信噪比很低,信号解调面临挑战,可能导致较大的测量误差。为了准确解调埋藏在噪声中的信号并获取速度信息,需要对获取的海试测量数据进行进一步算法处理。采用自适应滤波算法有效降低了多普勒信号中混杂的高频噪声干扰,提高了海试原始数据频域信号的信噪比,并利用寻峰算法更准确地获取了谱峰值。结果表明,与直接读取原始数据的谱峰值相比,经过该算法处理后,激光差分多普勒流速仪与声学多普勒流速仪比测的流速拟合度平均误差为0.2163 cm/s,误差降低了25.5%,表明该算法对激光多普勒测速信号解调是有帮助的。Objective In the field of physical oceanographic research,seawater flow velocity is one of the key parameters,primarily measured using acoustic Doppler velocimeters.In recent years,laser Doppler technology has made significant advancement in seawater flow velocity measurement.Laser Doppler velocimetry,with its simple and integrable structure,is expected to be a complementary technique with acoustic Doppler velocimeters in marine applications.Compared to acoustic velocity measurement techniques,laser Doppler velocimeters offer several advantages:their shorter wavelength(in the micron range)allows for the study of smaller-scale water features,and they can resist noise interference generated by underwater vehicles when used with unmanned underwater vehicles.However,due to seawater absorption and scattering,the detected signal is extremely weak and buried in strong noise,posing challenges for Doppler signal demodulation.Moreover,limited by the sampling frequency,there exists an error between the peak position of the obtained data spectrum and the true frequency.Therefore,effectively removing noise interference and improving measurement accuracy are crucial for laser Doppler velocimeters.In this paper,an adaptive filtering algorithm is employed to denoise the collected signal,followed by fast Fourier transform to enhance the signal-to-noise ratio.Three peak-finding algorithms are compared,and the Gaussian-LM algorithm is selected to process the power spectrum of the signal,bringing the peak position closer to the real peak value and thereby improving the demodulation accuracy of the Doppler signal and significantly reducing the error caused by noise.Methods The principle of laser Doppler velocimetry is illustrated in Fig.1(a).A laser beam is split into two equal beams by an optical fiber splitter after passing through a single-mode optical fiber.These two beams are then collimated into parallel beams by a collimator and directed onto a plano-convex lens at the end,which focuses the parallel beams onto a specific point

关 键 词：激光多普勒测速 自适应滤波 寻峰算法 信号解调 

分 类 号：TN911.7[电子电信—通信与信息系统]