选择性平均的φ-OTDR分布式光纤扰动传感系统阈值算法

Selective average based threshold algorithm for φ-OTDR distributed fiber-optic sensing system

阈值的准确设定是有效降低φ-OTDR分布式光纤扰动传感系统误报和漏报率的关键。针对该问题,提出了一种基于选择性平均的φ-OTDR分布式光纤扰动传感系统阈值算法,采用相关差值预挑选的方式确定信号模板,进行阈值模板匹配。理论和实验研究表明:提出的选择性平均阈值算法,能够更有效设定阈值,提高信噪比,降低φ-OTDR分布式光纤扰动传感系统的误报和漏报率,与直接平均和移动平均阈值算法相比,所提出的选择性平均阈值算法将误报率分别降低了5%和3%,漏报率均降低了2%;信噪比分别提升了2.55 d B、1.1 d B。所提出的算法有助于提高φ-OTDR分布式光纤扰动传感系统在实际应用中可靠性。

Accurate threshold is the key factor for reducing both of missing and nuisance alarm rates,which is essential for the φ-OTDR distributed fiber-optic sensing system. In order to solve this problem effectively, the algorithm based on the selective average was proposed. During this proposed algorithm, a pre-selection scheme was achieved using the correlation difference method to determine a signal template.Then, the match of threshold template can be realized. Theoretical and experimental results show that by the proposed algorithm the threshold can be obtained to decrease the missing and nuisance alarm rates,and improve the signal-to-noise ratio（SNR） of the φ-OTDR distributed fiber optic sensing system. In comparison with current direct and moving average algorithm, the missing alarm rate is decreased by 2%,and the nuisance alarm rate is decreased by 5% and 3%. What′s more, the SNR is increased by 2.55 d B and 1.1 d B, respectively. In conclusion, the proposed algorithm was also useful to improve the real-time reliability of the system for the practical applications.