Signal processing method for simultaneously improving BOTDR (Brillion optical time domain reflectometer) spatial resolution ratio and frequency shift measuring precision

Abstract

A signal processing method for simultaneously improving a BOTDR (Brillion optical time domain reflectometer) spatial resolution ratio and frequency shift measuring precision is used for processing time domain signals of a BOTDR by means of Cohen time-frequency analysis. The signal processing method includes the steps: acquiring broadband time domain signals of the BOTDR and leading a sampling rate fs to be four times of the highest frequency fm of the signals, namely fs>=4fm; processing the acquired time domain signals of the BOTDR by means of Cohen time-frequency analysis to obtain corresponding time-frequency distribution; and acquiring frequency spectrum information of time points, namely acquiring time-frequency distribution of the signals, finding positions with strain or temperature change in the frequency spectrum information and performing Cohen time-frequency analysis for the signals at the positions after STFT (short time Fourier transformation) processing in order to decrease calculated amount. By the aid of the signal processing method, the contradiction between the BOTDR spatial resolution ratio and the frequency shift measuring precision caused by the uncertainty principle in signal processing can be overcome.

Description

technical field [0001] The present invention relates to signal processing for Brillouin optical time domain reflectometers (BOTDR). In BOTDR signal processing, the Cohen-like time-frequency analysis method can alleviate the contradiction between spatial resolution and frequency shift measurement accuracy caused by the uncertainty principle in traditional signal processing methods, so that these two performance indicators can be better at the same time. Effect. Background technique [0002] Brillouin Optical Time Domain Reflectometer (BOTDR) is a fully distributed optical fiber sensing system based on spontaneous Brillouin scattering in optical fiber, which can be used to monitor the strain and temperature information along the optical fiber. Compared with the Brillouin optical time domain analyzer (BOTDA) based on stimulated Brillouin scattering (SBS), BOTDR has the advantages of single-ended measurement and breakpoint measurement. However, due to the extremely weak self-p...

AI Technical Summary

Problems solved by technology

While FWHM is related to the smallest detectable Brillouin frequency shift δv B There are relationships Among them, SN R represents the signal-to-noise ratio, so the larger the FWHM, the worse the frequency shift measurement accuracy

Therefore, the uncertainty principle in signal processing leads to a contradiction between BOTDR spatial resolution and frequency shift measurement accuracy

In the BOTDR system using STFT and frequency sweep method, these two performance indicators are difficult to achieve good results at the same time

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