Wang Jingru, Wang Zhihong, Wang Yuzhe, Liu Jie, Ji Xufei
Appl Opt. 2017 Nov 1;56(31):8777-8784. doi: 10.1364/AO.56.008777.
For the scanning near-infrared spectrometer, the employments of traditional digital demodulation algorithms require that the sampling frequency is an integral multiple of the measured signal frequency. However, the measured signal frequency is unstable, and the sampling frequency is a fixed value in the spectrometer, which affects the accuracy of amplitude demodulation results. To improve the signal-to-noise ratio of spectra, this paper proposes an improved digital demodulation algorithm based on frequency correction. Through theoretical analysis, simulations, and experiments, the improved digital demodulation algorithm based on frequency correction was compared with a digital demodulation algorithm based on the average of the absolute value in a complete period. The results showed that the former algorithm decreased the noise caused by the fluctuation of the measured signal frequency. The signal-to-noise ratio of spectra increased from 626 to 1124, and the measurement time increased only 0.73%.
对于扫描近红外光谱仪，传统数字解调算法的应用要求采样频率是被测信号频率的整数倍。然而，被测信号频率不稳定，而光谱仪中的采样频率是固定值，这影响了幅度解调结果的准确性。为了提高光谱的信噪比，本文提出了一种基于频率校正的改进数字解调算法。通过理论分析、仿真和实验，将基于频率校正的改进数字解调算法与基于完整周期绝对值平均值的数字解调算法进行了比较。结果表明，前一种算法降低了被测信号频率波动引起的噪声。光谱的信噪比从626提高到1124，测量时间仅增加了0.73%。
