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I
摘 要
锁相放大技术是一种可在极强噪声环境中提取特定频率信号幅值和相位的
技术。锁相放大技术基于相敏检测原理,以与待测信号具有相同频率和固定相位
关系的信号作为参考信号,测量得到相对于参考信号的待测信号的幅值和相位。
作为仪器设备的锁相放大器功能丰富,被广泛应用于传感器信号提取、材料物理
性质测试、生物信号检测等领域。但在实际应用中存在参数设置繁琐、数据可视
化程度低、复杂测试中时间常数和灵敏度设置不精确等诸多问题。针对测试中需
要手动调整多重参数、自动化程度低、数据处理不便等问题,采用 MATLAB 设
计了计算机控制的锁相放大器测试系统。主要工作如下:
(
1
)简要介绍了
SR830
型锁相放大器的功能结构、信号检测原理以及关键
参数。为了更好的设计系统,首先分析了可能影响系统的噪声源。然后设计了计
算机控制的交流电流源与锁相放大器的测试系统。计算机通过 GPIB-USB-HS 接
口卡与交流电流源及锁相放大器通讯互联。使用
MATLAB
程序实现了对交流电
流源和锁相放大器的控制、数据的读出与图形化。
(2)基于 MATLAB APP Designer 平台设计了专用 APP,主要从界面控件
层、功能层、代码层对设计进行实现。采用模块化布局将多种控件布置于
APP
主界面与参数设置界面,通过设计各模块的功能来实现常用的测控操作。利用锁
相放大器的状态字节来监测系统的运行状态,并设计自动参数获取功能,解决了
锁相放大器参数设置繁琐、不能适应跨量程测试的问题。同时,结合数据提取与
实时测试实现了多参数数据的可视化对比,提高了系统的可视化程度。
(3)使用 APP来控制系统对实验室所研发传感器元件的电压输出信号进行
测试。首先,分析了不同参数设置下锁相放大器的锁定效果,以确定锁相放大器
的默认参数设置和不同测试需求下的精确参数设置;然后,采集传感器元件在交
流激励驱动下的电压信号,分析了其输出中一次谐波和三次谐波分量随激励的变
化规律;最后,结合
APP
的常用测试功能,对传感器元件进行了特性表征,获
得了其电压信号与风速的关系。
研究的创新在于结合 MATLAB 设计了一种锁相放大器测试系统,并将其应
用于传感器元件在交流激励下的特性表征。结果表明,系统能够实现对锁相放大
器的高效控制,能够以精确的参数设置和多参数的数据可视化功能更好的提取有
用信号,实现了功能复杂的测试。可结合待测对象的特点对测试系统加以修改。
具有界面友好、易于使用、扩展性好等优点,从而具有良好的实际应用价值。
关键词:锁相放大器;自动测试系统;传感器测试;MATLAB APP Designer
II
Abstract
Phase-locked amplification is a technique that can extract the amplitude and
phase of a signal at a specific frequency in an extremely noisy environment. Based on
the principle of phase-sensitive detection, the lock-in amplification technique uses a
signal with the same frequency and fixed phase relationship as the signal to be
measured as the reference signal, and measures the amplitude and phase of the signal
to be measured relative to the reference signal. As an instrumentation device with rich
functions, the lock-in amplifier is widely used in the fields of sensor signal extraction,
material physical property testing, and biological signal detection. However, there are
many problems in practical applications such as cumbersome parameter settings, low
data visualization, imprecise time constants and sensitivity settings in complex tests.
To address the problems of manual adjustment of multiple parameters, low
automation and inconvenient data processing in testing, a computer-controlled lock-in
amplifier testing system is designed by using MATLAB. The main work is as follows:
(1) Briefly introduces the functional structure, signal detection principle and key
parameters of SR830 lock-in amplifier. In order to better design the system, the noise
sources that may affect the system are first analyzed. Then a computer-controlled test
system of AC current source and lock-in amplifier is designed. The computer was
interconnected with the AC current source and the lock-in amplifier through a
GPIB-USB-HS interface card communication. The control, data readout and graphing
of the AC current source and lock-in amplifier were implemented using MATLAB
program.
(2) A dedicated APP was designed based on the MATLAB APP Designer
platform, and the design was implemented mainly from the interface control layer,
functional layer, and code layer. A variety of controls are arranged in the main
interface and parameter setting interface of APP using modular layout, and common
measurement and control operations are realized by designing the functions of each
module. The status byte of the lock-in amplifier are used to monitor the operation
status of the system, and the automatic parameter acquisition function is designed to
solve the problem that the parameter setting of the lock-in amplifier is cumbersome
and cannot adapt to cross-range testing. Meanwhile, the combination of data
extraction and real-time testing realizes the visualization of multi-parameter data
comparison and improves the visualization of the system.
(3) Use the APP to control the system to test the voltage output signal of the
III
sensor element developed in the laboratory. First, the lock-in effect of the lock-in
amplifier with different parameter settings was analyzed to determine the default
parameter settings of the lock-in amplifier and the precise parameter settings for
different test requirements; then, the voltage signal of the sensor element driven by
AC excitation was collected and the variation law of the first and third harmonic
components in its output with excitation was analyzed; finally, the common test
functions of the APP were combined to Finally, the relationship between the voltage
signal and the wind speed is obtained by characterizing the sensor element with the
common test function of APP.
The innovation of the research is to design a lock-in amplifier test system with
MATLAB and apply it to the characterization of the sensor element under AC
excitation. The results show that the system enables efficient control of the lock-in
amplifier, better extraction of useful signals with precise parameter settings and
multi-parameter data visualization functions for functionally complex tests. The test
system can be modified by combining the characteristics of the object to be tested. It
has the advantages of friendly interface, easy to use and good expandability, thus
having good practical application value.
Keywords: lock-in amplifier; automatic test system; sensor test; MATLAB APP
Designer
IV
目 录
摘 要
............................................................................................................................
I
目 录......................................................................................................................... IV
图清单...................................................................................................................... VIII
表清单........................................................................................................................XII
变量注释表.............................................................................................................. XIII
1 绪论............................................................................................................................1
1.1 研究背景及意义.............................................................................................1
1.2
国内外研究现状
.............................................................................................3
1.3 主要研究工作.................................................................................................5
1.4 章节安排.........................................................................................................6
2
锁相放大器结构及原理............................................................................................7
2.1
锁相放大技术
.................................................................................................7
2.2 SR830 锁相放大器功能结构..........................................................................9
2.3 SR830 锁相放大器的检测原理....................................................................13
2.4 SR830
锁相放大器的关键参数
....................................................................15
2.5 本章小结.......................................................................................................18
3
测试系统设计..........................................................................................................19
3.1 系统结构.......................................................................................................19
3.2
控制端设计
...................................................................................................19
3.3 测试端设计...................................................................................................20
3.4 数据采集端设计...........................................................................................23
3.5
噪声分析与抗干扰设计
...............................................................................24
3.6 系统搭建与正确性验证...............................................................................27
3.7 本章小结.......................................................................................................29
4
基于 APP Designer 的测控 APP 开发.................................................................. 30
4.1
设计需求与平台选择
...................................................................................30
4.2 APP 界面设计................................................................................................32
4.3 功能模块与实现...........................................................................................36
4.4
本章小结
.......................................................................................................47
5
系统测试应用与结果分析
......................................................................................48
V
5.1 系统控制参数调试.......................................................................................48
5.2 静态特性实验...............................................................................................52
5.3
动态特性实验
...............................................................................................64
5.4 本章小结.......................................................................................................67
6
总结与展望..............................................................................................................68
6.1 总结...............................................................................................................68
6.2
展望
...............................................................................................................68
参考文献
......................................................................................................................70
作者简历
......................................................................................................................76
学位论文原创性声明
..................................................................................................77
学位论文数据集
..........................................................................................................78
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资源评论
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