SNR Improvement of QEPAS System by Preamplifier Circuit Optimization and Frequency Locked Technique
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Preamplifier circuit noise is of great importance in quartz enhanced photoacoustic spectroscopy (QEPAS) system. In this paper, several noise sources are evaluated and discussed in detail. Based on the noise characteristics, the corresponding noise reduction method is proposed. In addition, a frequency locked technique is introduced to further optimize the QEPAS system noise and improve signal, which achieves a better performance than the conventional frequency scan method. As a result, the signal-to-noise ratio (SNR) could be increased 14 times by utilizing frequency locked technique and numerical averaging technique in the QEPAS system for water vapor detection.
KeywordsQEPAS system preamplifier circuit frequency locked method noise optimization
This work was supported by the National Natural Science Foundation of China (Grant Nos. 61405105 & 61475085), the Shandong Provincial Natural Science Foundation, China (Grant No. ZR2014FQ015), Science and Technology Development Project of Shandong Province (Grant No. 2014GGX101007), and the Fundamental Research Funds of Shandong University (Grant Nos. 2014HW016 & 2014YQ011).
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