基于锁相放大器的微弱信号检测研究

发布时间：2018-06-20 00:01

本文选题：微弱信号 + 数字锁相放大器　；参考：《中南大学》2014年硕士论文

【摘要】：摘要：微弱信号检测是随着工程应用而不断发展的一门学科。近年来,微弱信号检测相关研究已经成为一个热点研究领域,具体表现在对微弱信号检测方法的探寻、对微弱信号检测系统的设计、对微弱信号检测仪器的研发。本文中主要研究了利用锁相放大器进行有用信号提取的微弱信号检测原理与实现方法。首先介绍了微弱信号检测的基本理论与常见的几种检测方法,重点介绍了利用数字锁相放大器进行信号检测的原理。在此基础上,结合数字锁相放大器的相关检测原理,给出了数字锁相放大器的整体设计方案,着重从相关检测原理算法和移相算法方面对数字锁相放大器的设计作了深入探讨。重点研究了采样频率与相关运算结果的关系,在设计的过程中先使用MATLAB进行算法上的模拟,从模拟结果发现参考信号为方波而采样频率与信号频率成一定关系时,系统相关运算存在固有误差。为减少该误差,提出了将动态采样率的方法引入数字锁相放大器设计中,运算发现动态采样的采样频率数越多,奇点产生的误差越少,有效地解决奇点问题。最后,使用Lab VIEW对设计的系统进行仿真测试。测试结果表明该数字锁相放大器在信号幅度为5V、噪声标准差小于等于50时(SNR=-34.04dB),能有效地检测出频率为500kHz以下的信号,系统检测结果与理论计算值的相对误差基本不超过2%。
[Abstract]:Absrtact: weak signal detection is a subject developing with engineering application. In recent years, the research on weak signal detection has become a hot research field, which is manifested in the exploration of weak signal detection methods, the design of weak signal detection system and the development of weak signal detection instruments. In this paper, the principle and realization of weak signal detection using PLL amplifier are studied. Firstly, the basic theory of weak signal detection and several common detection methods are introduced, and the principle of signal detection using digital phase-locked amplifier is emphatically introduced. On this basis, combined with the correlation detection principle of the digital phase-locked amplifier, the whole design scheme of the digital phase-locked amplifier is given, and the design of the digital phase-locked amplifier is discussed in detail from the aspects of the correlation detection algorithm and the phase-shifting algorithm. The relationship between sampling frequency and related operation results is studied emphatically. MATLAB is used to simulate the algorithm in the design process. When the reference signal is square wave and the sampling frequency is related to the signal frequency, the simulation results show that the sampling frequency is related to the frequency of the signal. There are inherent errors in the system correlation operation. In order to reduce the error, the method of dynamic sampling rate is introduced into the design of digital phase-locked amplifier. It is found that the more sampling frequency of dynamic sampling, the less the error of singularity, which effectively solves the singularity problem. Finally, LabVIEW is used to simulate and test the designed system. The test results show that the digital phase-locked amplifier can effectively detect signals with a frequency below 500kHz when the signal amplitude is 5V and the noise standard deviation is less than or equal to 50. The relative error between the system test result and the theoretical calculation value is not more than 2.
【学位授予单位】：中南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN722;TN911.23

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