Research On Embedded Cross-Correlation Demodulation System For Interferometric Sensor

With the development of optical fiber sensing technology, interferometric optical fiber Fabry-Perot sensor has become one of the earliest sensors applied in practical engineering of its unique advantages. Optical fiber Fabry-Perot sensor, with its simple structure, compact size and light weight, has long taken a leading place in measuring the value of displacement,temperature, vibration, pressure, sound and the like, and is so with in sustaining enduring stability and sharp sensitivity. Particularly, the demodulation methods which are classified into two main types: intensity demodulation and phase position demodulation, crucially guarantee the reach of each standard. This paper, on the basis of some precious researches,deeply focuses on Cross Correlation Demodulation System of Optical Fiber Fabry-Perot Sensor and its main contents are as follows:Firstly, around the background of the research, the development status of conventional phase position demodulation and correlation demodulation methods of Optical fiber Fabry-Perot sensor is introduced.Secondly, this paper thoroughly analyzes the working principle of Cross Correlation Demodulation techniques, which is based on optical wedges, after which simulates the output signals of specific broadband light sources and reflectivity. Discuss the impact of each parameter on the output signal, and determine the original cavity length of F-P cavity to provide ideas for overall scheme design of the demodulation system. CCD subdivision algorithm is introduced and improving the conventional barycenter method.lThirdly, the Cross Correlation Demodulation System of Optical Fiber Fabry-Perot Sensor is designed, including both hardware design and software design. FPGA is chosen as main control chip in hardware design. The hardware design part of the system is composed of photoelectric conversion module, analog-to-digital converter, data transmission module and DSP module; the software design part of the system is mainly responsible for generating driving schedule, firmware of USB chip and compiling device driver program, as well as processing work of Butterworth filter and linear CCD subdivision algorithm.Finally, debug each part of the demodulation system to ensure the correctness of the output results. And set up experiment platform to test and verify the resolution of the system.It is known from the experiment results that the system can be achieved on linear CCD signal acquisition and processing functions and basically reach its designing requirements.