Sonobuoy system

Abstract

This is a proximity fuse intended to detonate an underwater mine or torpedo when it is underneath a ship. The apparatus takes soundings upward toward the surface S of the sea, and toward the hull T of a ship if one is present. Three criteria must be met before the weapon can be fired. First, the reflecting surface must slope more steeply than could a natural surface 70 i $ T I transmitter near the surface and a hydrophone array some 10 000 ft below. Once the outer casing has fallen away, the array unfolds into its operating configuration. Twelve radial arms 71 suspend the hydrophones 70 in a three-dimensional array. There are 60 hydrophones, connected in pairs, to provide 30 separate signals. By time-division multiplexing, the 30 signals and a compass reference signal are transmitted to the aircraft, where the 30 channels are sorted out and 24 contiguous receiving beams are formed. A second buoy carries a supply of explosive charges, lowers them to the same depth as the hydrophones, and detonates them one at a time on command by radio from the aircraft.--LB wave. The sequence of soundings 31, 32, 33 does not show sufficient slope, but the sequence 33, 34, 35, etc. meets the first criterion. Second, after sufficient slope has occurred, the echo distance must decrease by at least a predetermined amount B below its average value.. This criterion is satisfied by sounding 38. Finally, to be sure the target is a ship and not debris, the second criterion must be met repeatedly by a certain number of subsequent soundings.--LB 4,323,992 43.30.Vh DEPTH SOUNDER REPEATER STRUCTURE AND METHOD 4,322,827 43.30.Vh RANGE EXPANDER FOR SONAR SYSTEM Ronald G. Weber, assignor to Lowrance Electronics, Incorporated 30 March 1982 (Class 367/99); filed 22 September 1980Echo sounders which indicate depth by a revolving lamp or by a recorder are limited in shallow water by the maximum practical speed of the indicating mechanism. This patent removes that limitation, and can be applied even to existing echo sounders. The apparatus stores the echo signals in a random access memory, and reads them out for display at a fraction of the rate at which they were received. The fraction is usually 1/2, but it could be 1/4, 1/8, or any power of 1/2. It results from the fact that to shift a binary number to the right is equivalent to dividing the number by 2. The apparatus is simple, and is easily put together with simple components that are commercially available.--LB 4,323,988 43.30.Vh SONOBUOY SYSTEM