Distributed Optical Fiber Sensor System And Stability Analyse

The technology of distributed optic fiber sensing was brought forward in 70th's, a series of sensing mechanism and measure systems turned up and were used gradually in many fields. Nowadays, it has been one of the most promising technologies in optic fiber sensing. Among them, Fiber Distributed Temperature measurement is developed in recent years for a real-time measurement of the spatial distribution of temperature. Distributed optical fiber sensor system can sensing the change of temperature along the optical fiber by the form of continuous function of distance.Fiber Distributed Temperature Sensor System Institute is set at home and abroad that the use of an advanced semiconductor laser technology, Fiber optical filter technology, high-speed photoelectric conversion, signal acquisition technology, independently developed and manufactured high-tech products. Uninterrupted to the automatic measurement, the need is particularly applicable to large-scale multi-point measurement of occasions, It is a traditional substitutes of temperature sensor, with high accuracy, data transmission and reading speed, adaptive good performance advantages.System is particularly suited to the power, oil, gas storage, chemicals, iron and steel, underground tunnels, coal mines along the way or large temperature measurement occasions is needed, the need for anti-conductive, waterproof, EDM regional defense is especially irreplaceable advantages, If a fire sprinkler system can be achieved by combining organic integration of the Security Monitoring System.The infection of stability about the distributed fiber sensor, Reliability is complicated. The major factor in detector (avalanche photodiode APD) temperature drift, Light Source (semiconductor laser diode LD) temperature drift and the power supply, optical time domain reflectometer performance, A / D and D / A conversion and the accuracy of the algorithm for data processing aspects. Among them, the main source of stability in the performance of its transmission power and the stability of the stability spectrum. This paper mainly from the launch of the stability of power start, pumped from the drive to improve the stability of the link to how to improve the fiber optic distributed temperature sensor system stability. Other factors in the improvement, is also based on the theory of ideas. For example, if APD can gain constant work in two ways :The first, keep the environment temperature and bias voltage remains constant; The second is the bias with temperature changes by a certain percentage. According to this theory, we propose two ways to achieve the right temperature compensation APD, APD to enable stable and normal work. They are : constant temperature and pressure and temperature compensation voltage bias; select good AD cards, its conversion function of the accuracy of testing the system requirements, the same temperature, The noise factor is the impact on small links mainly to solve the problem. To address this, we have proposed algorithm on the software provided by the manufacturers of formula corresponding amendment, thus, the accuracy can be higher; Measurement data for calibration of the choice made, in order to be more accurate; Finally, Papers also focus on research work, namely, the LD driver circuit and a temperature control circuit design. In the paper, I learned from the semiconductor laser driver circuit design method is proposed in this paper several circuit design, and made some experiments, for the final design of the system provides a guiding reference. Finally, I also directed at other parts of the design, such as the device provides a selection of ideas ,and so on. To paves the further work.In short, Fiber Distributed Temperature is a real-time, on-line, multi-point temperature measurement system. It uses the fiber back Raman scattering effect of temperature, the temperature of information acquisition with the opto-electronic signal, via signal processing, Demodulation temperature will be real-time information extracted from the noise and out, from one angle, it is a typical temperature fiber communications network; in the time domain, use of fiber optical time-domain reflectometry measurements in the temperature point positioning, From this angle it is a typical temperature Laser radar system. The stability of system have an important role for the practicability. Therefore, the design of the system stability should be studied carefully.