The Research Of Distributed Optical Fiber Temperature Sensor Signal Processing

Distributed optical temperature measurement and signal processing is a newly established multi-disciplined applied technology along with recent rapid developments in the fields of electronics, communication and information system, photo-electricity, optical fiber sensor as well as auto-control. The distributed optical fiber temperature sensor system can monitor many points temperature (or other physics variability such as strain) along a single optical fiber at same time, and can locate the position of temperature field by means of optical time domain reflect. It is widely used in monitor of produce process, fire alarm system of coal mine, tunnel and fuel depots, seepage and leakage of dams. At present this technology has become in the optical fiber sensor technology one of most promising technical.The distributed optical fiber temperature sensor signal processing research is quite important, because the back scattering Raman signal with the information of temperature is weak or completely submerged in noise. As a result, the denoising level determined the accuracy of the whole system, weak signal measurement must be used in this system. This article has conducted the comprehensive research to the Raman distributed optical fiber temperature sensor signal processing, has analyzed the Raman distributed optical fiber temperature sensor performance index and emphasis analyzed the temperature resolution and its improvement methods. Increasing pulse width of the probe pulse can improve the signal to noise ratio and temperature resolution of the conventional single Raman distributed optical fiber temperature sensor, but degrades the spatial resolution. Using Golay complementary codes correlation technique and digital averaging technique may has much better performance than conventional Raman distributed optical fiber temperature sensor. Then has discussed the application of higher-order cumulant in the Raman distributed optical fiber temperature sensor signal detection, proposed based on the bispectrum Raman distributed optical fiber temperature sensor signal detect method, has restrained the system noise effectively, obtained tended to the zero temperature resolution.