Railroad monitoring system, railroad monitoring device, railroad monitoring method, and non-transitory computer-readable medium

A railroad monitoring device, comprising:

• a reception unit configured to receive an optical signal from at least one communication optical fiber included in a cable laid on a railroad;
• and
• a detection unit configured to detect a pattern according to a state of the railroad, based on the optical signal, and detect an abnormal state of the railroad, based on the detected pattern according to the state of the railroad.

A railroad monitoring method by a railroad monitoring device, the method comprising:

• receiving an optical signal from at least one communication optical fiber included in a cable laid on a railroad;
• and
• detecting a pattern according to a state of the railroad, based on the optical signal, and detecting an abnormal state of the railroad, based on the detected pattern according to the state of the railroad.

(canceled)