基于快速数字锁相的溶解氧检测优化设计

溶解氧浓度检测在水产养殖和环境监测中具有重要的意义。本文提出了一种基于快速数字锁相的溶解氧检测优化设计，利用快速数字锁相算法与过采样技术，实现了荧光信号和调制信号的快速相位解调，并得到二者相位差，根据Stern-Volmer方程求出溶解氧浓度值。本文分析了调制频率对测量结果的影响，选择合适的调制频率用于测量，并利用最小二乘法对测量结果进行拟合，拟合后的确定系数R-square为0.999 25。实验数据表明，测量结果相对误差（RE）小于±1.5%，相对标准差（RSD）小于4%，稳定时间小于50 s。本文提出的优化设计不仅具有较高的测量精度，还简化了硬件设计，降低了成本。

Optimized design of dissolved oxygen measurement based on fast digital lock-in

The detection of dissolved oxygen concentration has great significance in aquaculture and environmental monitoring. In this paper, we introduce an optimized design for the measurement of dissolved oxygen based on fast digital lock-in. Using a fast digital lock-in algorithm and oversampling technology, fast-phase demodulation of the signal is realized. First, the phase difference between the demodulated and modulated fluorescence signals is determined, and the dissolved oxygen concentration is calculated using the Stern-Volmer equation. We then analyze the influence of modulation frequency on the measurement results, select the appropriate modulation frequency for measurement, and use the least squares method to fit the measurement results. The coefficient of determination R-square for this study was 0.999 25. A comparison with experimental data revealed that the relative error of our proposed method was less than ±1.5%, the relative standard deviation was less than 4%, and the stabilization time was less than 50 s. The optimized design introduced here has high measurement accuracy while also simplifying the hardware design and reducing cost.