Surface impact location system

The design of a free-floating portable system to obtain range and direction of an object striking the sea surface relative to the platform is described. The impact signals are received by hydrophones, processed to obtain time difference in signal arrivals, and telemetered to a shore station. Of special interest is the platform for the hydrophones which is comprised of a long slender spar, and cable suspended below it. Range measurement accuracy requires that two hydrophones be suspended vertically at known depths separated by fifty feet, and held vertical within two inches of each other in high sea states. Sea Tests indicate that this requirement has been met by the unique platform design.