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Dynamic Multi-frequency Digital Lock-in Algorithm and Its Application |
Xie Qiong; Li Jian-ping;Gao Xiao-guang; Jia Jian |
State Key Laboratory of Transducer Technology, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China |
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Abstract A dynamic multi-frequency digital lock-in algorithm is presented in this paper. By this algorithm, the amplitude of the signal composed of the fundamental and the harmonics can be obtained. And in addition, the problem of frequency drift is solved by rectifying the reference frequency dynamically. Compared with the traditional method, this novel algorithm uses more information and does not need to choose the reference signal. When applied to NDIR gas concentration measurement, it not only widens the measurement range, but also improves the sensitivity of the detection.
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Received: 25 August 2008
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