Influences of pulse parameters on the performance of double-pulse φ-OTDR

摘要

In the past decade, an increasing number of studies of double-pulse 0-OTDR systems have been reported, but so far, there are no studies specifically analyzing the influences of double pulses on system performance. In this paper, we construct a theoretical model of the double-pulse 0-OTDR system, analyze the interference process of the system theoretically, and make conjectures on spatial resolution and demodulation range. On the basis, we build a double-pulse 0-OTDR experimental setup based on Sagnac balanced interferometer. The feasibility of the proposed theory is verified by experiments altering the probe pulse parameters and localizing two-point disturbances at different frequencies. The results also indicate when pulse width is greater than the pulse interval, this system offers more accurate positioning capabilities and a continuous demodulation range with high fidelity. The conclusions provide a reference for the selection of appropriate double-pulse parameters for similar systems, and the theoretical model offers a methodological suggestion for exploring other types of double pulses or even multi-pulse systems.

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