Precision analysis for underwater sound source localization in ocean acoustic environment with time delay estimation method

The localization precision of underwater sound source is influenced significantly by the ocean acoustic environment. Aiming at the engineering applications at sea, we analyze the problem of localization precision on an underwater platform with time delay estimation method. We first compute the estimation errors of the pitch and azimuth angle introduced by such factors as the time delay estimation error, the inhomogeneous ocean media, the instability of the platform, and the fluctuation of sound transmission based on theoretical analysis. Then we obtain the localization error with varying depth of platform and varying range of sound source by using the error transmission formula. We also compare the localization error of a planar array with a 3-demensional array, and in conditions of compensating the sound ray reflection effect or not. The results are partially verified with the data recorded in sea trials, which show that the inhomogeneous ocean media contributes most to the total localization errors. When employing a 3-demensional array instead of a planar array, and measuring the ocean sound speed profile to compensate the sound ray refraction, the relative localization error would reduce from the maximum of 30% to 10%. The above results give a guidance for taking effective measures to improve the localization precision of the underwater sound source.