Zhang Shengzhao, Li Gang, Lin Ling, Zhao Jing
School of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China.
School of Chinese Medicine Engineering, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China.
Rev Sci Instrum. 2016 Aug;87(8):085102. doi: 10.1063/1.4959978.
A digital lock-in detection technique is commonly used to measure the amplitude and phase of a selected frequency signal. A technique that uses a square wave as the reference signal has an advantage over the one using a sinusoidal wave due to its easier implementation and higher computational efficiency. However, demodulating multiple-frequency composite signals using square wave reference may result in interference between channels. To avoid interference between channels and reduce the computational complexity, we modify the calculations and determine the optimal parameter settings of the low-pass filter and carrier frequency, as detailed in this paper. The results of our analysis show that when the length of the average filter and carrier frequencies are properly set, the interference between the channels is removed. This optimization produces the digital lock-in detection suitable for measuring multi-channel sensor signals.
数字锁相检测技术通常用于测量选定频率信号的幅度和相位。由于实现更容易且计算效率更高，使用方波作为参考信号的技术比使用正弦波的技术更具优势。然而，使用方波参考解调多频复合信号可能会导致通道间的干扰。为避免通道间的干扰并降低计算复杂度，我们修改了计算方法并确定了低通滤波器和载波频率的最佳参数设置，本文将详细说明。我们的分析结果表明，当平均滤波器的长度和载波频率设置适当时，通道间的干扰会被消除。这种优化产生了适用于测量多通道传感器信号的数字锁相检测。
