An Algorithm for Determining the Peak Frequency of BOTDR Under the Case of Transient Interference

An algorithm based on spectra splicing is proposed to determine the peak frequency of Brillouin spectrum under a transient interference. The peak frequency calculated is only 0.79 MHz lower than that obtained based on the whole Brillouin spectrum when the frequency interval is 5 MHz. Discussions on the performance of our algorithm with and without spectral shift are conducted in light of the practical situation. Imposing a random shift on the primal Brillouin spectrum between -5 and 5 MHz, only 200 incomplete Brillouin spectra are required for splicing to gain a reliable value of the peak frequency with a frequency interval of 5 MHz. Moreover, the efficiency can be significantly improved by increasing the frequency interval, but the improvement is limited since higher frequency interval means more information loss of the whole Brillouin spectrum. This method is helpful in deciding the Brillouin frequency shift when the external interference lasts for a very short time, such as sound barriers and wind tunnel tests. It provides guidelines for the design of distributed optical fiber sensing systems.