Abstract: An acoustic transponder method and apparatus provides a high degree of frency and target strength selectivity by utilizing two or more concentrically disposed, hollow spheres each containing acoustically refractive fluids. The invention provides the possibility of using spheres of a variety of diameters and as well a number of different refractive fluids, enabling the production of an acoustic transponder having a wide variety of selective frequency responses as well as effective target diameters.

Abstract: A deployment system is disclosed for deploying a vertical, sub-surface bud, underwater acoustic sensor array in the ocean which includes a mechanical load transfer and cable separation mechanism which is embodied as a rigid triangular member. The vertical, sub-surface buoyed underwater acoustic sensor array is attached to a support cable which is connected at one end to the sub-surface buoy and at its other end to one of the vertices of the rigid triangular member. An anchor is attached to another vertex of the rigid triangular member and the third vertex of the triangular member is fitted with a strain relief/cable support, rotatable leg that is in turn attached to the deployment or shore cable. After deployment, the triangular member becomes the mechanical link between the array anchor and the array's vertical support member. It also acts as a mounting surface for the necessary electrical cable junction boxes or other required instrumentation and hardware.