| Fiber micro-vibration sensor technology had come out as early as in the1970s, is a kind of integrated technology which involves optics, precision instruments, electronics, signal processing, and other disciplines. And it plays an important role in areas such as military defense, information intelligence. In this technology, the digitization processing of the follow-up signal is the core of the sensor system. For the past few years, the development of digital signal processing technology has greatly improved the optical fiber vibration sensing technology mature.This thesis firstly introduces the development history of the optical fiber sensing technology and related applications, then summarizes the current research status of digital optical fiber micro-vibration sensing phase generated carrier(PGC) modulation demodulation technology, and clarify this topic research significance. In the theory section of the article, mainly describes the sensing mechanism of the optical fiber Michelson interferometer micro vibration signal, and gives the mathematical model of PGC demodulation.According to the need of laboratory related projects, this paper designed a kind of digital demodulation system based on DSP, including photoelectric conversion, differential drive, AD conversion, DDS oscillation circuit, McBSP interface circuit, DDR2, FLASH, reset circuit, JTAQ and power supply system. The key technology of the system is analyzed, and determine, using AD7986as analog to digital converter, and the sampling precision and sampling rate respectively can reach18-bits and800kS/s. Finally, according to the amount of data to be processed, we chose the TI Da Vinci series of TMS320DM6437as the main processor.In order to reduce the project cost of development and design risk, the demodulation system can be divided into front-end module and TMS320DM6437minimum system two parts in this paper. Finally, we have finished the circuit design of the whole system in hardware, welding and debugging, etc. |
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