Research And Improvement On Measurement Accuracy Of Distributed Optical Fiber Temperature Measurement System

Distributed optical fiber temperature sensor which based on the Raman scattering principle was put forward in the end of 1970's,then it became a hot topics because of it's superior performance and great application fields. In large scope of temperature monitoring applications, the traditional electric sensor is incapable, however, Distributed optical fiber temperature sensor just provides a new measuring method.The system circuit is introduced based on the introduction of background and work principle of distributed optical fiber temperature sensor, and it's work principle and main function modules are introduced. According to the optical time-domain positioning principle, the main factors which influence system spatial resolution are analyze in this paper, the improvement measures are put forward. The increase of the pulse width of conventional monopoles distributed optical fiber temperature sensor can improve the temperature resolution, but, at the same time, it should reduces the spatial resolution, so a new improvement measure that using main vibration amplification fiber laser instead of traditional semiconductor lasers is put forward; As the temperature resolution is decided by signal-to-noise ratio which is the ratio of signal strength and system noise, so, the main influence factors of system temperature resolution are analysis in this paper from those aspects, the improvement methods are put forward in this paper such as using modulation amplification mode and using high transmission efficiency two-way coupler.But the excessive system noise, the measurement cycle of the traditional accumulate average method is too long, and the hot volts value would be cut at a certain accumulate number, the wavelet signal processing method, that combining small amount of accumulative average with Daubechies wavelet, is put forward in this paper, and the related conclusions validated by experiments. The treatment effect of the new method on reference signal and temperature-sensitive signal are compared by experiments, the application effect of the new method in practical measurement system is also be validated by experiments.