Department of Geophysics, GeoForschungsZentrum-Potsdam (GFZ) Telegrafenberg, 14473 Potsdam, Germany.
Institute of Applied Geosciences, Technical University of Berlin, Ernst-Reuter-Platz 1, 10587 Berlin, Germany.
Sensors (Basel). 2023 Apr 4;23(7):3735. doi: 10.3390/s23073735.
Distributed Dynamic Strain Sensing (DDSS), also known as Distributed Acoustic Sensing (DAS), is becoming a popular tool in array seismology. A new generation of engineered fibers is being developed to improve sensitivity and reduce the noise floor in comparison to standard fibers, which are conventionally used in telecommunication networks. Nevertheless, standard fibers already have extensive coverage around the Earth's surface, so it motivates the use of the existing infrastructure in DDSS surveys to avoid costs and logistics. In this study, we compare DDSS data from stack instances of standard multi-fiber cable with DDSS data from a co-located single-fiber engineered cable. Both cables were buried in an area located 2.5 km NE from the craters of Mt. Etna. We analyze how stacking can improve signal quality. Our findings indicate that the stack of DDSS records from five standard fiber instances, each 1.5 km long, can reduce optical noise of up to 20%. We also present an algorithm to correct artifacts in the time series that stem from dynamic range saturation. Although stacking is able to reduce optical noise, it is not sufficient for restoring the strain-rate amplitude from saturated signals in standard fiber DDSS. Nevertheless, the algorithm can restore the strain-rate amplitude from saturated DDSS signals of the engineered fiber, allowing us to exceed the dynamic range of the record. We present measurement strategies to increase the dynamic range and avoid saturation.
分布式动态应变传感（DDSS），也称为分布式声传感（DAS），在地震台阵领域已成为一种流行的工具。新一代的工程光纤正在被开发出来，与传统用于电信网络的标准光纤相比，其灵敏度更高，噪声基底更低。然而，标准光纤已经在地球表面广泛覆盖，因此，在 DDSS 调查中利用现有的基础设施来避免成本和物流问题是合理的。在这项研究中，我们将来自标准多光纤电缆的堆叠实例的 DDSS 数据与来自同一位置的单根工程光纤电缆的 DDSS 数据进行了比较。这两条电缆都埋在埃特纳火山口东北 2.5 公里处的一个区域。我们分析了堆叠如何改善信号质量。我们的研究结果表明，堆叠由五个标准光纤实例（每个 1.5 公里长）组成的 DDSS 记录可以降低多达 20%的光学噪声。我们还提出了一种算法，可以纠正由于动态范围饱和而产生的时间序列中的伪影。虽然堆叠可以降低光学噪声，但对于从标准光纤 DDSS 的饱和信号中恢复应变速率幅度来说还不够。然而，该算法可以从工程光纤的饱和 DDSS 信号中恢复应变速率幅度，从而使我们能够超过记录的动态范围。我们提出了一些测量策略来增加动态范围并避免饱和。
