Method of detecting the presence of an enemy submarine

Abstract

1. The method of detecting the presence of an enemy submarine within a gi body of water without revealing the position of a listening vessel outside said body of water to said enemy submarine which comprises the steps of: Submerging a self-contained sound source on the floor of the ocean on the central vertical axis of said body of water, said sound source having a sufficient power output to enable sound waves to be transmitted to an enemy submarine within said body of water and be reflected therefrom to points outside said body of water, Propagating a high intensity, nondirectional sound signal from said sound source within said body of water, Positioning a listening vessel a predetermined distance outside said body of water, said predetermined distance being that required for said listening vessel to detect an echo of a sound signal originating at said sound source and reflected from said enemy submarine, while the sound from the source reflected from said listening vessel into said body of water will be of too low a level to be detected at said enemy submarine within said body of water and detecting an echo of a sound signal originating at said sound source and reflected from said enemy submarine at said listening vessel.

Dependencies are inferred from the claim text.