Abstract: A method and apparatus for compensating sensitivity fluctuations in signals received from respective groups of hydrophones for the purpose of subsequent signal processing, the groups being arranged in a predetermined sequence (0, 1, 2, . . . i) to form a transducer arrangement, wherein the received signals are influenced by the sensitivity of the hydrophones and/or the gain of preamplifiers connected to the outputs of the hydrophones. The energy value (W.sub.i) for the received signals of each group of hydrophones is determined and a median energy curve (W.sub.m (.theta.)) is derived from the energy values (W.sub.i) as a function of the sequence of the groups of hydrophones. A correction value is formed for the signals received from each group of hydrophones from a comparison of the respective energy value (W.sub.i) with the energy curve (W.sub.m (.theta.)) and the received signals are corrected with the correction value.

Abstract: A method for displaying a battle situation under consideration and indication of the movement and position of friendly forces and with the position and motion behavior of targets being derived from angle and distance information, wherein: the display takes place on an electronic display device; one or a plurality of passive bearing systems and/or passive distance measuring systems are provided to furnish angle and distance information of targets which radiate wave energy; position, course and speed are calculated for every target per time interval and displayed as motion vectors; angle and distance information on the targets from given time intervals are used for the display of target paths; markers are associated with the targets resulting from their changes in position and/or the characteristics of signals received from the bearing and/or distance measuring systems and these markers are displayed at the associated target positions; and uncertain measurement regions are calculated from the measuring toleranc

Abstract: A circuit arrangement for forming a succession of group signals in the ranging art from received signals originating from an array of adjacent signal receiving transducers, each successive group signal being associated with a respective group characteristic and being based on the signals received by a respective group of adjacent transducers forming part of the array. The succession of group signals is processed to form a representation of the mean, or average, value of a predetermined number of successive group signals, and a representation of the ratio of the value of one of the group signals of that predetermined number of signals to the mean value is produced.