Resolution of 3-D undersea noise directionality estimates using a towed line array

This talk characterizes the relationship between the number of towed array measurement headings and mean angular resolution for an underwater noise directionality estimation technique. Previous work by Wagstaff J. Acoust. Soc. Am. 63, 863–869 (1978) suggests a technique using a towed line array with multiple array headings along with the commonly present (typically unwanted) vertical pitch of the array to disambiguate the mean undersea noise field directionality. We characterize the relationship between the measurement parameters and the angular resolution (both in azimuth and elevation) of this technique. This relationship will be discussed in a 2-dimentional (2-D) and 3-dimentional (3-D) context. In both cases, the angular resolution of the technique tends to improve as headings are added, with the improvement also being affected by array length and, in the 3-D case, array pitch. In the 3-D case, an inverse relationship between azimuthal and vertical resolution as array pitch and elevation angle vary is discussed. Additionally, the effect of uncertainty in array motion on the mean resolution (and variance in resolution) using this technique is analyzed.