Inverted USBL (Ultra-Short Baseline) is an underwater acoustic positioning system used in inertial navigation to determine the position of a surface or aerial vehicle relative to an underwater object. It is the reverse of traditional USBL, where the transceiver is placed underwater and tracks an acoustic beacon on a surface vessel, autonomous underwater vehicle (AUV), or unmanned surface vehicle (USV).
How Inverted USBL Works in INS?
Underwater Transceiver – A USBL transducer array is mounted on the seafloor, a submarine, or an underwater station.
Beacon on the Surface Vehicle – An acoustic beacon is placed on the ship, drone, or buoy, sending signals.
Time-of-Flight Calculation – The underwater transceiver measures the signal travel time and angle to compute the position of the surface beacon.
INS Integration – The position fixes from the inverted USBL system are used to correct INS drift, improving navigation accuracy.
Applications of Inverted USBL in INS
✔ Submarine-to-Surface Communication – Allows submarines to track ships or buoys without surfacing.
✔ AUV & ROV Navigation – Used for deep-sea exploration and underwater docking.
✔ GNSS-Denied Environments – Provides external positioning updates to correct INS drift in underwater operations.
Advantages of Inverted USBL for Inertial Navigation
✔ Accurate Positioning Without GNSS – Critical for submarines and deep-sea vehicles.
✔ Long-Range Tracking – Can track targets over several kilometers.
✔ Enhances INS Performance – Provides periodic position corrections to reduce inertial drift.
