Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia.
College of Electrical and Electronic Technology, Benghazi 0021861, Libya.
Sensors (Basel). 2021 Jun 23;21(13):4299. doi: 10.3390/s21134299.
For almost a half-decade, the unique autocorrelation properties of Golay complementary pairs (GCP) have added a significant value to the key performance of conventional time-domain multiplexed fiber Bragg grating sensors (TDM-FBGs). However, the employment of the unipolar form of Golay coded TDM-FBG has suffered from several performance flaws, such as limited improvement of the signal-to-noise ratio (SNIR), noisy backgrounds, and distorted signals. Therefore, we propose and experimentally implement several digital filtering techniques to mitigate such limitations. Moving averages (MA), Savitzky-Golay (SG), and moving median (MM) filters were deployed to process the signals from two low reflectance FBG sensors located after around 16 km of fiber. The first part of the experiment discussed the sole deployment of Golay codes from 4 bits to 256 bits in the TDM-FBG sensor. As a result, the total SNIR of around 8.8 dB was experimentally confirmed for the longest 256-bit code. Furthermore, the individual deployment of MA, MM, and SG filters within the mentioned decoded sequences secured a further significant increase in SNIR of around 4, 3.5, and 3 dB, respectively. Thus, the deployment of the filtering technique alone resulted in at least four times faster measurement time (equivalent to 3 dB SNIR). Overall, the experimental analysis confirmed that MM outperformed the other two techniques in better signal shape, fastest signal transition time, comparable SNIR, and capability to maintain high spatial resolution.
近半个世纪以来，Golay 互补对（GCP）的独特自相关特性为传统时域复用光纤布拉格光栅传感器（TDM-FBG）的关键性能增添了重要价值。然而，Golay 编码 TDM-FBG 的单极性形式的应用受到了一些性能缺陷的困扰，例如信噪比（SNIR）的提升有限、背景噪声大以及信号失真等。因此，我们提出并实验实现了几种数字滤波技术来减轻这些限制。移动平均值（MA）、Savitzky-Golay（SG）和移动中位数（MM）滤波器被用于处理位于大约 16 公里光纤之后的两个低反射率 FBG 传感器的信号。实验的第一部分讨论了在 TDM-FBG 传感器中仅部署从 4 位到 256 位的 Golay 码。结果，实验证实最长的 256 位码的总 SNIR 约为 8.8 dB。此外，在所述解码序列中单独部署 MA、MM 和 SG 滤波器，分别可使 SNIR 进一步显著提高约 4、3.5 和 3 dB。因此，仅部署滤波技术就可使测量时间至少快四倍（相当于 3 dB 的 SNIR）。总的来说，实验分析证实 MM 在信号形状、最快信号转换时间、可比的 SNIR 和保持高空间分辨率的能力方面优于其他两种技术。
