Analysis of the accuracy of a LBL-based underwater localization procedure

The use of Long Baseline (LBL) systems for localizing underwater vehicles is quite consolidated, as they guarantee a good nominal accuracy, not dependent on the operative depth and almost constant at any point inside the area delimited by the transponders. However the real achievable accuracy can be affected by different factors, mainly related with the knowledge of some environmental parameters (like the speed of sound), the quality of the employed instrumentations, and the level of calibration of the system, after its deployment in water. The paper specifically addresses the accuracy of a LBL-based localization procedure and presents the results of an error budget analysis. For each considered error source, a closed form of the induced localization error is derived and discussed with the intent of enabling the characterization of the real obtainable accuracy within a typical application. The overall study is finally supported and validated by a detailed set of simulative results.