The study of the Raman-based optical fiber-folded distributed temperature sensing system with simplex code

In this article, the simplex code (S code) technique was applied to the distributed fiber Raman temperature sensing system of fiber folded structure. The measured anti-Stokes signal is processed to obtain the temperature information of the whole fiber length. First, the effect of S code length on the system error was investigated and the analysis shows that at a certain level of noise, by increasing the code length, the error of temperature measurement can be largely reduced, but the system space resolution is kept unchanged. Then, the relationship of the noise level, superposition times and temperature error was studied by simulation. The conclusion can provide the basis for the optimization of temperature demodulation time. The research was of great significance to improve the temperature measurement accuracy of distributed optical fiber sensors and to reduce measurement errors.