BOTDA Sensing System Based on Differential Golay Coding and Deconvolution Algorithm

Performance enhanced BOTDA sensors that allows for simultaneous optimization of sensing range and spatial resolution is proposed and demonstrated in this work by using differential Golay coding and deconvolution algorithm, where pulse coding is used to extend the sensing distance, meanwhile deconvolution processing is utilized to enhance the spatial resolution. Specifically, differential coding pulses are used to eliminate the Brillouin Frequency Shift (BFS) distortion that results from the deconvolution processing. In addition, to mitigate the distortion of Brillouin trace imposed by the erbium-doped fiber amplifier (EDFA) transient effect, pre-distortion is employed for the pulse train to ensure a more accurate decoded Brillouin trace. Different widths of pulse pairs and different sampling rates have been investigated to optimize the performance of sensing system. For proof of concept, 25 km sensing range and 0.2 m spatial resolution are demonstrated by using 60/40 differential Golay coding pulse train and deconvolution algorithm. The proposed technique manages to alleviate the contradiction between sensing range and spatial resolution of BOTDA sensors, which paves the way to enable both long sensing range and high spatial resolution simultaneously.