数字正交锁相放大器在光纤瓦斯检测系统中的应用

Application of Digital Quadrature Lock-in Amplifier in Optical Fiber Gas Detection System

为了实现高精度实时的瓦斯气体检测系统,介绍了数字正交锁相放大器,主要对其基本原理和结构进行了分析,利用FPGA和A/D转换器件,设计了数字锁相放大器的硬件电路。将数字正交锁相放大器应用于光纤瓦斯检测系统中,避免了传统锁相放大器在系统中手动移相和直流漂移的产生。同时放大微弱信号,更精确地得到所需的幅值信息,再由幅值间接得到相应的瓦斯浓度值。通过实验表明,在实际应用中能及时、精确地实现井下瓦斯浓度检测,有效地减少了安全隐患,并且可以提高工作效率和测量的准确性。

In order to get the gas concentration timely and accurately,this paper introduces the basic the digital quadrature lock-in amplifier, and analyses the principle and structure. The hardware circuit of digital quadrature lock-in amplifier was designed by FPGA and A/D. That the digital quadrature lock-in amplifier applied to the optical fiber gas detection system can avoid manual phase-shifted and measurement error of concentration by DC drift caused by Traditional lock-in amplifier. At the same time, the digital quadrature lock-in amplifier can amplify weak signal and get the amplitude more accurately. At last, the corresponding gas concentration is obtained by amplitude. The experiment results show that in production, using the digital quadrature lock-in amplifier can detect the gas concentration timely and accurately and reduce the potential safety hazard effectively. Meanwhile, it can improve the efficiency and reduce the gas concentration detection equipment costs.