Method of Precise Sensing Channel Positioning for Das Based on the Amplitude Spectrum in the Frequency Domain

For the applications of distributed acoustic sensing technology (DAS), it is important to precisely identify the sensing channels along an optical fiber to correctly locate the vibrations and improve the accuracy of DAS. An experiment was designed to verify the method of precise channel identification for DAS. A bending element was inserted into the sand to excite the constant-frequency signals point by point along the optical fiber. A DAS interrogator was used to collect the vibrations of the optical fiber. The average of the normalized time domain signals and the amplitude of the specific constant frequency in the frequency domain are analysed. The parameters of the skewness of the amplitude-channel curve (SACC) and the relative shift of the amplitude peak (RSAP) are proposed to identify the boundary of the adjacent sensing channels. The accuracy of the sensing channel positioning is better than the spacing of the excitation points