Method and apparatus for finding the bearing of sound-Emitting targets

Abstract

The invention relates to a method for finding the bearings of sound-emitting targets by means of a receiving antenna 10 whose received signals 14 are supplied to a beamformer 16 in order to form at least three mutually offset directional characteristics. In the case of an imaginary display on a polar diagram, a main lobe 28 is overlapped from both sides by the main lobes 26 of adjacent directional characteristic0 such that these two main lobes 26 touch or intersect at the level of that reception angle ? at which the main lobe 28 of the central directional characteristic has its maxmium 30. These main lobes 26, 28 are used to produce direction-dependent amplitude functions FA, FB, FC. The sum function FS of the amplitude functions FA, FC which is then calculated is differentiated twice in order to determine its second derivative 50. The local maxmia 56 which result from the second derivative function 50 indicate possible, potential signal directions. A statistical analysis method,uses these possible, potential signal directions Zi to determine actual signal directions with the associated signal strengths. The invention also, relates to an apparatus for carrying out a method such as this.