基于动态采样的锁相放大微弱信号检测  

Weak Signal Detection Method Based on Lock-In Amplifier

作　　者：聂娅琴[1] 许雪梅[1] 李奔荣[1] 杨兵初[1] 

机构地区：[1]中南大学物理与电子学院,长沙410083

出　　处：《传感技术学报》2013年第9期1243-1247,共5页Chinese Journal of Sensors and Actuators

基　　金：国家自然科学基金项目(61172047;61071025)

摘　　要：基于相关检测原理设计了一种数字锁相放大器,重点研究了采样频率与相关运算结果的关系。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,首次将动态采样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。基于LabVIEW软件对所设计的检测系统进行了仿真测试,测试结果表明该数字锁定放大器在信号幅度为5 V、噪声标准差小于等于50时(SNR=-34.04 dB),能有效地检测出频率为500 kHz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%。A digital lock-in amplifier is designed based on correlation detection principle, it focused on the relation between sample frequency and correlation operation result. It is find that there exists inherent error in correlation operation when reference signal is square wave and the signal frequency has a relationship with sample frequency. To reduce the error,it introduced a dynamic sample to design digital lock-in amplifier at the first time, the result showed that the more the number of sample frequencies, the less the singularity error. Simulation and test to the designed detecting system were got based on LabVIEW software,the result showed that the digital lock-in amplifier can detect the signal which frequency is under 500 kHz effectively when signal amplitude is 5 V, standard deviation of the noise is less than 50 （ SNR = -34.04 dB ）, and the proportional error between system test result and theoretical value are mainly under 2%.

关 键 词：微弱信号 锁相放大器 采样率 相关运算 

分 类 号：TN722.5[电子电信—电路与系统] TN713.1