METHOD ESTABLISHING DIRECTION OF ARRIVAL OF ECHO SIGNAL ( VARIANTS ) Russian patent published in 2003 - IPC

FIELD: underwater acoustics, sound fixing and ranging, detection of active objects. SUBSTANCE: there are proposed several variants of implementation of method. Emission under pulse mode and signal reception from direction of major maximum of radiation pattern of receiving-transmitting, multielement, equidistant antenna, emission and reception of signals are carried out in proper frequency range. One or two additional maxima positioned in symmetry with reference to major maximum are formed in same frequency range in radiation pattern. If echo signal is received, direction of arrival of echo signal is found as direction of major maximum, if it is not received as direction of additional maximum. To define direction more exactly in presence of two additional maxima on altered frequency radiation pattern is turned till one of additional maxima coincides with initial, radiation is carried out on altered frequency and if echo signal is fixed this direction is assumed to be direction of arrival of echo signal, in its absence- direction of another additional maximum on initial frequency is considered as proper direction. Radiation and reception of signals are conducted in turn or simultaneously on two different frequencies f_a, f_b. If echo signal is received on both frequencies direction of arrival of echo signal is defined as direction of major maximum, if it received on one frequency-as direction of additional maximum on given first frequency. To define direction more exactly in presence of two additional maxima radiation pattern is turned on second frequency till one additional maximum coincides with direction of additional maximum of first frequency on which signal was received and radiation is emitted. When echo signal is received on second frequency this direction is defined as direction of arrival of echo signal, in absence of echo signal direction of arrival of another additional maximum on first frequency is considered to be direction of arrival of echo signal. EFFECT: increased precision and capability of direction finding, expansion of frequency band by factor of two and more towards higher frequencies in which range direction of arrival of echo signal is established unambiguously when wave dimensions between antenna elements are same. 4 cl, 4 dwg