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针对激光器频率漂移对相位敏感光时域反射计(φ-OTDR)的性能影响,文中采用后向瑞利散射的一维脉冲响应模型对其进行了理论分析。在实验室测试中,搭建了臂长差为100 m的非平衡MZ干涉仪来实时监测激光器的频率漂移;并通过测试三种不同频率漂移的激光器下的φ-OTDR系统性能验证了理论分析的正确性。理论分析及实验结果表明,激光器的频率漂移是引起φ-OTDR曲线波动的重要因素,频率漂移越大,其引起的φ-OTDR曲线波动就越大;当频率漂移高达几百MHz/min时,在时域上已难以区分出是频率漂移引起的扰动还是入侵事件引起的扰动,但仍能在频域中将频率漂移噪声分辨出来。
In view of the influence of laser frequency drift on the performance of phase-sensitive OTDR (φ-OTDR), a one-dimensional impulse response model of backward Rayleigh scattering is used in this paper. In the laboratory test, a non-equilibrium MZ interferometer with a difference of arm length of 100 m was set up to monitor the laser frequency drift in real time. The performance of the φ-OTDR system under three different frequency drift lasers was verified by theoretical analysis Correctness The theoretical analysis and experimental results show that the frequency drift of the laser is an important factor causing the fluctuation of the φ-OTDR curve. The larger the frequency drift, the greater the fluctuation of the φ-OTDR curve. When the frequency drift reaches several hundred MHz / min, In the time domain, it has been difficult to distinguish whether it is caused by the frequency drift or the disturbance caused by the intrusion event, but it can still distinguish the frequency drift noise in the frequency domain.