Abstract
For underwater source localization, accurate estimation of the time of flight (or travel time) is required and the observed waveform may include Doppler (waveform dilation). The source waveform, thus, needs to be sensitive to estimate both time of flight and Doppler. In this study, we compare two waveforms : Linear Frequency Modulated sweeps (LFMs) and Maximum Length Sequences (MLSs) with identical center frequency (6 kHz) and bandwidth (2 kHz). During an at-sea experiment conducted in March 2022 near in the Mediterranean Sea, near the coast of Toulon, a mobile source transmitted the two waveforms, recorded by a 192-hydrophone moored bilboard array. The source-array distance ranged from 2.5 to 8 km, and the source was towed at a constant speed (∼1.5 m/s) and depth (∼50m). The analysis of the gathered data shows that the MLS waveform outperforms the LFM waveform for estimating time of flight (uncertainty reduced by a factor 4) and radial velocity (uncertainty reduced by a factor 20). Preliminary results focus on single hydrophone processing, but possible applications to 2D array processing are discussed for localizing the source in range-dependent environments.
Published Version
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