REAL-TIME QGQG PHASE UNWRAPPINGANDSAR/INSAS DEMFUSION FOR AUTONOMOUSUNDERWATER TERRAIN-AIDEDNAVIGATION

Autonomous Underwater Vehicles (AUVs) require precise navigation, velocity tracking, and depthcontrol to operate ef ectively in dynamic underwater environments. Traditional methods, such as Inertial Navigation Systems (INS) and Doppler Velocity Logs (DVL), are af ected by drift errors andreduced accuracy over longer missions. To address these challenges, this research work integrates microwave-based navigation with a Quality-Guided Quasi-Geodesic (QGQG) phase unwrappingtechnique, a method that traces optimal unwrapping paths through high-quality phase regions usingaquasi-geodesic traversal strategy. This enhances terrain-aided navigation (TAN) and seabed mapping. A key innovation is the fusion of Synthetic Aperture Radar (SAR) and Interferometric SyntheticAperture Sonar (InSAS) data to provide reliable Digital Elevation Models (DEMs) for AUVnavigation. This hybrid approach enables real-time unwrapped phase data extraction, enhancingAUV trajectory accuracy while minimizing drift errors. MATLAB-based simulations validate thesystem, demonstrating a reduction of positional error from 15 m to 1.5 m using Particle Filtering andachieving velocity estimation accuracy of ±0.05 m/s. These results advance the field of underwater navigation, paving the way for GPS-independent, real-time, autonomous marine exploration.