基于双M-Z干涉型光纤振动传感器及其PGC解调技术的研究

发布时间：2018-02-28 15:03

本文关键词： 干涉型光纤传感器相位生成载波调制解调技术振动测量数字信号处理　出处：《天津理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：干涉型光纤传感器相比与其他传感器有诸多优势,如精确的分辨率、灵敏度较高、较大的动态响应范围,因而其可以长期在特定环境下工作。在振动传感器、温度传感器、液位传感器、折射率传感器、应变传感器、湿度传感器等领域中都有广泛的应用。相位生成载波(PGC)调制解调技术具有检测灵敏度高,动态范围大,抗噪声能力强,避免随机相位衰落等特点,是一个应用前景非常广阔的零差解调方法。使用数字信号处理芯片技术不仅可以克服模拟器件带来的随机直流漂移问题,而且具有很强的灵活性与可扩展性。本文基于PGC调制解调技术与数字信号处理技术,设计了两种级联型双M-Z干涉型振动传感系统,分别可以还原振动波形与测量振动点位置,并且提出了一种搭载在本系统中的PGC改进算法,完成待测信号的解调。本文的主要工作如下:第一,提出了一种级联型双M-Z干涉型光纤振动传感器的结构,该结构将调制端与传感端分别置于每个M-Z干涉仪的其中一个干涉臂,两个M-Z干涉仪以单模光纤相连。另外,还提出了一种基于基频混频的反正切-微分自相乘(Arctan-DSM)算法,该算法可以降低系统的采样频率,并且具有抗光强扰动与抗总谐波失真的优势。通过仿真分析验证以上理论的正确性与有效性。第二,提出了一种级联型双M-Z干涉型光纤振动传感定位系统的结构,该结构将两个完全相同的M-Z干涉仪用单模光纤相连,在每个M-Z干涉仪上进行相同的调制,单模光纤作为传感光纤,感测待测振动信号。并且,对该结构的定位原理进行了详细的理论研究。基于MATLAB仿真平台,对振动点位置进行仿真测量,并且研究了延迟光纤的长度与系统采样频率对该系统测量振动点的影响。第三,搭建了级联型双M-Z干涉型光纤振动传感系统,并对干涉光路、预处理电路以及数字解调系统这三个部分进行了相关实验。通过已搭建的完整的传感系统,完成了余弦振动信号与啁啾振动信号的正确解调,验证了该系统适用用于任意信号解调的结论。
[Abstract]:The interferometric fiber optic sensor has many advantages over other sensors, such as accurate resolution, high sensitivity, large dynamic response range, so it can work in a specific environment for a long time. Liquid level sensors, refractive index sensors, strain sensors, humidity sensors and other fields have been widely used. Avoiding random phase fading is a widely used homodyne demodulation method. Using digital signal processing chip technology can not only overcome the random DC drift caused by analog devices. Based on the PGC modulation and demodulation technology and digital signal processing technology, two cascaded double M-Z interferometric vibration sensing systems are designed, which can restore the vibration waveform and measure the position of the vibration point, respectively. An improved PGC algorithm is proposed to demodulate the signal to be tested. The main work of this paper is as follows: first, the structure of a cascaded double M-Z interferometric fiber optic vibration sensor is proposed. The two M-Z interferometers are connected by a single mode optical fiber. In addition, an algorithm based on the fundamental frequency mixing is proposed to solve the problem of Arctan-DSM, which is based on the fundamental frequency mixing of the two M-Z interferometers, in which the modulation terminal and the sensing terminal are placed in one of the interference arms of each M-Z interferometer respectively, and the two M-Z interferometers are connected with each other by a single mode optical fiber. The algorithm can reduce the sampling frequency of the system and has the advantages of resisting the intensity disturbance and the total harmonic distortion. The simulation results show that the above theory is correct and effective. In this paper, a structure of cascaded double M-Z interferometric optical fiber vibration sensing and positioning system is proposed. Two identical M-Z interferometers are connected with each M-Z interferometer by a single mode optical fiber, and each M-Z interferometer is modulated in the same way, and the single-mode fiber is used as the sensing fiber. The vibration signal is detected and the positioning principle of the structure is studied in detail. Based on the MATLAB simulation platform, the vibration point position is measured by simulation. The effects of the length of the delayed fiber and the sampling frequency of the system on the measurement vibration point of the system are studied. Thirdly, a cascade double M-Z interferometric optical fiber vibration sensing system is built, and the interference optical path is analyzed. Three parts of preprocessing circuit and digital demodulation system are experimented. The correct demodulation of cosine vibration signal and chirped vibration signal is accomplished through the complete sensing system. The conclusion that the system is suitable for any signal demodulation is verified.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP212;TN763

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