用于海底地震监测的光纤干涉型传感器解调方法研究

发布时间：2018-01-20 14:17

本文关键词： 光纤干涉型传感器相位生成载波光纤条纹计数相位测量　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：海啸作为一种常见的自然危害,严重影响了沿海居民的生活和安全,有效的实现海啸预警显得十分重要。近年光纤传感技术不断发展,由于光纤干涉型传感器体积小,质量轻,灵敏度高,耐腐蚀,抗电磁干扰的特点,成为海洋监测与预警方面的热门课题。海啸来临的时候会伴随着海底地震及海水的剧烈涨幅,因此通过光纤传感技术实现低频振动与水位水压的测量在海啸预警中具有重要意义。本文的主要研究目的为设计合适的干涉型光纤传感器实现振动与压力的测量,研究恰当的解调方法,提高测量的稳定性与可靠性。本文首先对海啸的产生原因及灾害进行了阐述,介绍了干涉型光纤传感器的发展历程,同时介绍了干涉型光纤传感器产生干涉的条件以及传感的结构。然后对适用于光纤干涉型传感器的解调方法进行了说明,重点介绍了相位生成载波调制解调算法与干涉条纹计数解调算法,两种方案分别适用于振动与压力的测量。接着对相位生成载波调制解调算法中的微分交叉相乘解调算法与反正切解调算法进行了分析,由于微分交叉相乘解调算法具有容易受光源扰动影响的缺点,反正切解调算法具有动态范围小的缺点,因此本文分别提出了一种改进的解调算法与一种反正切解调算法的相位补偿方案,并通过数值仿真进行了解调结果的对比论证,验证了改进方案的可行性。在压力测量方面通过结合过零检测方案与阈值判别方案提出了一种双向双阈值条纹计数方案并通过仿真进行了分析,分析表明该方案相对于传统算法的解调精度提高了4倍。搭建了基于迈克尔逊干涉的振动传感系统与基于马赫-增德尔干涉的压力传感系,最终在低频测量方面最低可以实现0.4 Hz的频率测量,振幅的测试范围大于100 d B.在压力方面可以实现π/4的相位改变量,25μm的光纤长度的改变量以及1.1 cm的液位改变量的测量。
[Abstract]:As a common natural hazard, tsunami has seriously affected the life and safety of coastal residents. It is very important to effectively realize tsunami warning. In recent years, fiber optic sensing technology has been developing continuously. Because of the small size, light weight, high sensitivity, corrosion resistance and electromagnetic interference resistance of optical fiber interferometric sensor. It has become a hot topic in ocean monitoring and early warning. When the tsunami comes, it will be accompanied by the sea floor earthquake and the sharp increase of sea water. Therefore, the measurement of low frequency vibration and water pressure through optical fiber sensing technology is of great significance in tsunami warning. The main purpose of this paper is to design a suitable interferometric optical fiber sensor to measure vibration and pressure. . Research on the appropriate demodulation method to improve the stability and reliability of the measurement. Firstly, this paper describes the cause and disaster of the tsunami, and introduces the development of interferometric optical fiber sensor. At the same time, the condition of interference and the structure of interferometric fiber sensor are introduced. Then the demodulation method suitable for fiber optic interferometric sensor is introduced. The algorithm of phase-generated carrier modulation and demodulation and the counting and demodulating algorithm of interference fringes are introduced in detail. The two schemes are suitable for the measurement of vibration and pressure respectively. Then the differential cross-multiplication demodulation algorithm and the inverse tangent demodulation algorithm of phase-generated carrier modulation and demodulation algorithm are analyzed. Because the differential cross multiplication demodulation algorithm is easy to be affected by the disturbance of the light source, the inverse tangent demodulation algorithm has the disadvantage of small dynamic range. Therefore, this paper proposes a phase compensation scheme of an improved demodulation algorithm and a kind of algorithm based on the tangent demodulation, and compares the demodulation results by numerical simulation. The feasibility of the improved scheme is verified. In the aspect of pressure measurement, a bidirectional double-threshold fringe counting scheme is proposed by combining zero-crossing detection scheme with threshold discrimination scheme and analyzed by simulation. The analysis shows that the demodulation accuracy of this scheme is four times higher than that of the traditional algorithm. A vibration sensing system based on Michelson interference and a pressure sensing system based on Mah-Zendel interference are built. Finally, the lowest frequency measurement of 0.4 Hz can be realized in low frequency measurement, the measurement range of amplitude is larger than 100 dB, and the phase change of 蟺 / 4 can be realized in the aspect of pressure. The change of fiber length of 25 渭 m and liquid level of 1.1 cm were measured.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P715.5

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