Research And Design Of Distributed Optical Fiber Temperature Sensing System

The distributed optical fiber temperature sensing technology is used in real-time space temperature measurement, which can measure the temperature distribution situation of optical fiber form several kilometers to tens of kilometers. With a wide temperature range, high stability, anti-electromagnetic interference, flame-proof characteristics, it attracts widespread attention at home and abroad and achieves rapid development. Currently, because of its outstanding advantages, the distributed optical fiber temperature sensing system is widely used in industrial production, public security, defense and military fields.The basic theory of distributed optical fiber temperature sensing system is studied and analyzed, focusing on the Raman scattering and its temperature demodulation. Moreover, analysis of how to use OTDR (Optical Time Domain Reflectometer) positioned in space, realization of each fiber with temperature measurement points corresponding to the position.In this paper, the overall architecture of the distributed optical fiber temperature sensing system is designed, and analyzes the system performance index. This paper designs light source system which produces narrow pulse and can overcome the temperature drift, focuses on the pulse drive circuit and temperature control circuit, ensure produce stable and reliable pulse light source, and increase the optical power by Erbium-doped optical fiber amplifier. And to design the optical receiving system that can receive the optical signal and convert into electrical signals, mainly introduces the high voltage biasing circuit that produces hundreds of voltages for APD, describes photoelectric conversion circuit and signal amplification circuit. Then analyzes Noising processing algorithms when sampling, to eliminate signal noise and random interference. Use the ATmegal6MCU to control various subsystems, design bus communication program, MCU communicates with the main processor through the IIC bus.This paper tests the system to ensure that circuit to meet design requirements. Then test the bus communication to ensure accurate system communication. Finally, use5Km fiber to measure the temperature distribution of laboratory, and achieved good results, reflect the system is stable and meets the performance requirements.