Abstract The response of a quasi-distributed fiber optic sensing system to a short interrogation pulse can be considered as a sparse signal in the time domain. This attribute can be exploited to enhance its performance beyond the commonly accepted limits. The work described here is analogous to some compressed sensing systems, which can be adequately sampled at sub-Nyquist rates, based on knowledge of their sparsity in the spectral domain. Equivalently, it is shown here how the sparsity of the impulse-response of a Quasi-Distributed Acoustic Sensing (Q-DAS) system can be exploited to interrogate it at rates well above the limit dictated by the total duration of its impulse response. An additional improvement in performance is achieved by using a Perfect Periodic Auto-correlation (PPA) code, rather than a pulse, for interrogation of the system. Cross-correlating the raw response of the Q-DAS system with the original code retains the sparsity of the response and provides significant gain in SNR without losing spatial resolution. Experimentally, the method was utilized to implement a 76 km long acoustic sensing system and successfully detected 250 kHz ultrasound signal. This was achieved by interrogating the system at a rate of 971 kHz which is 737 times the inherent limit dictated by the duration of the impulse-response of the system.

中文翻译：

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准分布式光纤传感系统响应的稀疏性允许“超频”其询问

摘要 准分布式光纤传感系统对短询问脉冲的响应可视为时域中的稀疏信号。可以利用此属性来增强其性能，使其超出普遍接受的限制。此处描述的工作类似于一些压缩感知系统，基于对它们在频谱域中的稀疏性的了解，它们可以以亚奈奎斯特速率进行充分采样。同样，此处显示了如何利用准分布式声学传感 (Q-DAS) 系统的脉冲响应的稀疏性以远高于其脉冲响应总持续时间所规定的限制的速率对其进行询问。通过使用完美周期自相关 (PPA) 代码（而不是脉冲）来查询系统，可以进一步提高性能。将 Q-DAS 系统的原始响应与原始代码互相关保留了响应的稀疏性，并在不损失空间分辨率的情况下提供了显着的 SNR 增益。实验上，该方法用于实现一个 76 公里长的声学传感系统并成功检测到 250 kHz 的超声信号。这是通过以 971 kHz 的速率询问系统来实现的，该速率是系统脉冲响应持续时间规定的固有限制的 737 倍。