非线性超声短脉冲信号检测方法研究与实现  

Research and implementation of nonlinear ultrasonic short pulse signal detection method

作　　者：谢子成 郑隆浩 邹涌 唐立军[1,2] Xie Zicheng;Zheng Longhao;Zou Yong;Tang Lijun(School of Physics and Electronic Science,Changsha University of Science and Technology,Changsha 410114,China;Key Laboratory of Electromagentic Environment Detection and Modeling in Near-Earth Space of Hunan Province Universities,Changsha 410114,China)

机构地区：[1]长沙理工大学物理与电子科学学院,长沙410114 [2]近地空间电磁环境检测与建模湖南省高校重点实验室,长沙410114

出　　处：《电子测量与仪器学报》2025年第2期193-204,共12页Journal of Electronic Measurement and Instrumentation

基　　金：湖南省研究生科研创新项目(CX20210742)资助。

摘　　要：一般的微弱信号检测方法所使用的锁相放大技术对于高频短脉冲信号还存在困难。对于一般的锁相放大器而言,短脉冲信号达不到锁相放大器后级滤波器的建立时间,难以检测到微弱的高频短脉冲信号,因此提出了一种针对高频非线性超声短脉冲信号的检测方法。该方法在锁相放大技术的基础上,考虑到非线性超声信号为周期信号,在锁相放大器的前级增加数字平均环节,增大信号的信噪比。锁相放大环节中采用滑动均值滤波代替普通低通滤波器,根据最佳匹配原则,设置滑动均值滤波器的窗长度等于脉冲持续时间,实现只对脉冲信号进行的低通滤波,避免了普通低通滤波器对短脉冲信号建立时间不够的问题,最终实现高频非线性短脉冲信号检测的锁相放大。本系统采用数模混合电路,逻辑算法部署在FPGA上。采用微弱信号发射器与电脑端搭建测试平台,对系统进行测试。测试结果表明,在输入信号频率为分别为0.6、1、2、5、10 MHz的情况下,系统均能检测到脉冲长度为5μS,幅度为100 nV的脉冲信号,并且具有良好的线性度。选择频率为1 MHz的输入信号进行不同脉冲宽度的测试,系统能准确检测到脉冲长度为5、10、30μS,幅度大小为100 nV的脉冲信号。The phase-locked amplification technique used in the general weak signal detection method is still difficult for high frequency short pulse signal.For the general phase-locked amplifier,the short pulse signal cannot reach the establishment time of the post-stage filter of the phase-locked amplifier,so it’s difficult to detect the weak high-frequency short pulse signal.Considering that the nonlinear ultrasonic signal is periodic signal,add digital average to the front stage of the phase-locked amplifier to increase the signal-to-noise ratio of the signal.According to the principle of best matching,the window length of the moving mean filter is set equal to the pulse duration,so as to realize the low-pass filtering only for the pulse signal,avoiding the problem that the common low-pass filter does not have enough time to establish the short pulse signal,and finally realizing the phase-lock amplification of high-frequency nonlinear short pulse signal detection.The system uses mixed digital analog circuit,and the logic algorithm deployed on the FPGA.The weak signal transmitter and computer are used to build a test platform to test the system.The test results show that the system can detect the pulse signals with a pulse length of 5μS and amplitude of 100 nV when the input signal frequencies are respectively 0.6,1,2,5 and 10 MHz,and has good linearity.Select the signal with frequency of 1 MHz for different pulse width test,the system can accurately detect pulse signals with pulse length of 5,10,30μS and amplitude of 100 nV.

关 键 词：锁相放大器 滤波器 数字平均 短脉冲信号检测 

分 类 号：TN98[电子电信—信息与通信工程]