Experimental evaluation of a USBL underwater positioning system

This paper presents and experimentally validates two closed-form underwater acoustic positioning methods with experimental data from an Ultra-Short Base Line (USBL) system developed from scratch. The prototype underwater positioning device that is being developed is planned to be extensively used within the framework of the European TRIDENT project. Both positioning methods compute the localization of a transponder relatively to the USBL using the time of flight of underwater acoustic waves. Based on spread-spectrum signal processing techniques, specially designed Direct Spread Spectrum Signals (DSSS) are employed to improve the performance of the system and tackle multi-path detection problems and detectability in the presence of noise. A validation of the positioning schemes was conducted with experimental data using the USBL inside a harbor yielding satisfactory preliminary results and good performance.