System for determining the length of an optical fiber unwound from/remaining on a storage reel particularly housed in an underwater weapon

A system for determining a length of an optical fiber unwound from or remaining in at least one storage reel, the fiber being used as a medium for transmitting information between a weapon and an underwater vehicle from which the weapon has been fired, the system comprising:

• a backscattered light power meter for measuring the backscattered light power in the fiber;
• a backscattered light power signal analyzer for analyzing the backscattered light power signal and for detecting a backscattered light power discontinuity corresponding to a location of the fiber where the fiber leaves the reel;
• a localization analyzer for localizing the location along the fiber;
• and
• a calculator for determining from the localization and from a length of fiber initially wound on the reel, the length of fiber unwound from or remaining on the reel.