| CPC G01H 9/004 (2013.01) [G01D 5/353 (2013.01)] | 1 Claim |

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1. A signal loss detection method for distributed acoustic sensing (DAS) systems, comprising steps of:
collecting DAS data of channels from one time frame,
down sampling the DAS data and collecting down sampled DAS data,
calculating a standard deviation of each channel to get statistical power data from the down sampled DAS data,
removing an optical coupler effect on the statistical power data,
performing line fitting from each channel to two ends of the DAS system to find if an abrupt change in power levels with respect to the channels occurs or not,
selecting a best channel with minimum fit errors using a maximum likelihood estimation,
calculating a difference between two-line fits on the best channel,
comparing the difference with a threshold,
giving an alarm that there is a significant signal loss at the best channel if the threshold is exceeded.
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