Coherent arrays of drifting sonobuoys

Abstract

By incorporating a Global Positioning System (GPS) receiver into the electronics of an active or passive sonobuoy for determining a geoposition of each sonobuoy comprising an array of sonobuoys or a sonobuoy field, the position of each sonobuoy can be ascertained as the original position of the line of sonobuoys forming the array changes due to wind, sea state and currents. The GPS geoposition of the individual sonobuoys is transmitted to as receiving vehicle along with the acoustic signal obtained by the sonobuoy sensor. Utilizing an onboard computer, the receiving vehicle can compute a synthesized coherent array position. The military P(Y) code transmitted by the GPS satellites is utilized to determine the geoposition of the sonobuoy relative to the other sonobuoys to a degree of accuracy of 2 to 3 meters. If the use is by a civilian activity, the civilian coarse access (C/A) code may also be utilized with a decrease in individual sonobuoy accuracy to 100 meters, however, by application of a broadcast correction, the degree of accuracy obtained utilizing the military P(Y) code can be achieved.

What is claimed is: 
     
       1. A sonobuoy capable of broadcasting a sonobuoy geoposition comprising: a plurality of sonobuoys forming a line of sonobuoys;   means for receiving a geoposition of an individual sonobuoy in the line of sonobuoys from Global Positioning System (GPS) satellites;   means for sensing an acoustic noise generated by an object submerged within a medium;   means for converting the acoustic noise into an electromagnetic signal;   means for combining the electrical signal and the geoposition of the sonobuoy to form a combined electrical signal; and   means for transmitting the combined electrical signal to a receiving vehicle for analysis to determine a synthesized coherent array pattern of the line of sonobuoys.   
     
     
       2. A sonobuoy, as in claim 1, wherein the sonobuoy is an active sonobuoy. 
     
     
       3. A sonobuoy, as in claim 1, wherein the sonobuoy is a passive sonobuoy. 
     
     
       4. A method for compensating for the drift of a line of active or passive sonobuoys in the open ocean, comprising the steps of: receiving a geoposition of an individual sonobuoy in the line of sonobuoys from Global Positioning System (GPS) satellites;   sensing an acoustic noise generated by an object submerged within a medium;   converting the acoustic noise into an electromagnetic signal;   combining the electrical signal and the geoposition of the sonobuoy to form a combined electrical signal;   transmitting the combined electrical signal to a receiving vehicle; and   analyzing a received combined electrical signal to determine a synthesized coherent array pattern of the original line of sonobuoys to compensate for drift due to wind and sea state.