摘要
介绍了一种微弱信号的检测与锁定放大方法。通过模拟锁相环工作锁定待检微弱信号的频率,利用控制器测量该锁相环的输出频率,并根据该频率值控制直接数字合成电路产生同频信号,该信号作为相关检测所需的参考信号。系统采用乘法器和积分电路实现相关检测,通过步进调整参考信号的相位,使互相关值最大,获得与被测信号同频同相的再生信号,从而实现微弱信号的检测与放大。该方法能够实现频率检测及幅度检测等功能。经实验测试表明:在低信噪比条件下,该方法仍具有较好的线性测量特性和较高的准确度,可实现任意波形的微弱信号自动检测和再生放大。
The method of detecting weak signal and designing lock-in amplifier circuit was proposed , in which , having weak signal frequency obtained through analog PLL technology and the controller employed to detect phase-locked loop ’ s output frequency so that a reference signal for relevant detection can be obtained according to the same frequency produced by the frequency value-based direct digital synthesis circuit .The system employs multiplier and integrator to accomplish the relevant detection , and through adjusting the refer-ence signal step by step , the cross-correlation value can be maximized and the regeneration signal same as the measured signal in both frequency and phase can be obtained to implement detection and amplification of the weak signal , including both frequency and amplitude detection of the weak signal .The experimental tests show that this method has a high linearity at low SNR conditions and can be applied to the auto-detection and regen-erative amplification of the arbitrary waveform ’ s weak signal .
出处
《化工自动化及仪表》
CAS
2014年第5期509-512,共4页
Control and Instruments in Chemical Industry
基金
武汉工程大学校长基金资助项目
