数字锁相放大器在大气透射仪中的应用研究

Research on Digital Lock-In Amplifier in Transmissometer

为了提高大气透射仪的测量动态范围、测量精度及稳定性,用FPGA设计了双相数字锁相放大器,并结合低噪声运算放大器、低误差可编程增益放大器、高精度模数转换器,实现了大动态范围、高精度、超稳定的信号采集模块。测试表明该设计满足了大气透射仪在气象能见度小于50 m时μV级别信号的探测能力以及高气象能见度时精确、稳定测量的要求。

A two-phase digital lock-in amplifier is designed based on FPGA to improve the dynamic range, accuracy and stability of the transmissometer. Combined with low noise operational amplifier, low error programmable gain amplifier and high performance analog-to-digital converter, a high precision and super stable signal acquisition module with large dynamic range is realized. Test shows that this design satisfies the demands of transmissometer to measure the μV level signal when the atmospheric visibility is less than 50 m and precise and stable meaurement when atmospheric visibility is higher.