欠采样下外差干涉系统数字正交解调法  

Undersampling Digital Orthogonal Demodulation Method for Heterodyne Interference System

作　　者：马杰 黎敏[1] 吕海飞 郜洪云[1] 文晓艳 苏凯[2] Ma Jie;Li Min;LüHaifei;Gao Hongyun;Wen Xiaoyan;Su Kai(School of Science,Wuhan University of Technology,Wuhan,Hubei 430070,China;School of Water Resources and Hydropower Engineering,Wuhan University,Wuhan,Hubei 430070,China)

机构地区：[1]武汉理工大学理学院,湖北武汉430070 [2]武汉大学水利水电学院,湖北武汉430070

出　　处：《激光与光电子学进展》2021年第23期42-48,共7页Laser & Optoelectronics Progress

基　　金：国家自然科学基金(62075174,11974266,51879207);中央高校基本科研基金(WUT2020IB004,WUT2019IB014)。

摘　　要：光学外差干涉系统信号频率高,传统的过采样解调方法的成本高且数据量大,不利于实时解调监测。研究了欠采样数字正交解调方法,以降低外差系统采样频率,满足振动传感快速解调和实时监测的需求。首先理论分析了外差干涉系统欠采样的原理,得到了采样频率需满足的条件,即最小采样频率需大于信号带宽的2倍。对欠采样解调进行了实验验证,在PZT激振电压为0.5 V、外差频率为80 MHz时,利用20 kHz~10 MHz的采样频率均可实现相位解调,解调误差最大为0.3%,且不随采样频率的降低而增大。研究了采样频率大小与可测激振电压范围的关系,采样频率越高,可测电压范围越大。50,100,200 kHz采样频率分别可适用于1~7 V、1~14 V和1~20 V范围的解调。欠采样数字正交解调以其低成本、快速解调的优势在光学外差干涉系统领域有广阔的应用前景。Optical heterodyne interference systems have high signal frequency.The tranditional oversampling demodulation method has the disadvantages of high cost and large amount of data,so it is inconvenient for real-time demodulation monitoring.In this paper,an undersampling digital orthogonal demodulation method is studied to reduce the sampling frequency of a heterodyne system,so as to meet the demands of fast demodulation and real-time monitoring in vibration sensing.Firstly,the undersampling principle of a heterodyne interference system is analyzed theoretically to obtain the condition that the sampling frequency must meet,that is,the minimum sampling frequency should be more than twice of the signal bandwidth.Then undersampling demodulation is verified experimentally.For a vibration with a0.5 V piezoe-lectric transducer(PZT) excitation voltage and an 80 MHz heterodymium frequency,the phase could be demodulated with sampling frequency as low as 20 kHz-10 MHz.The largest demodulation error is 0.3%,and it does not increase with the decrease of sampling frequency.The influence of sampling frequency on measurable PZT excitation voltage range is studied.Higher sampling frequency leads to larger voltage range,and the linear demodulation intervals corresponding to 50,100,and 200 kHz sampling frequencies are 1-7,1-14,and 1-20 V,respectively.Undersampling digital orthogonal demodulation is believed to have extensive application prospects in optical heterodyne interference systems due to its low-cost and fast demodulation.

关 键 词：光通信 外差干涉 数字正交解调 欠采样 动态范围 振动传感 

分 类 号：O436.1[机械工程—光学工程]