METHOD FOR DETECTING NOISY OBJECTS IN THE SHALLOW SEA IN THE INFRASONIC FREQUENCY RANGE Russian patent published in 2023 - IPC G01S3/80 

FIELD: hydroacoustics.

SUBSTANCE: used in systems for detecting noisy objects in the infrasonic frequency range. The method includes receiving a noise signal by a combined receiver containing a sound pressure receiver and a three-component pressure gradient vector receiver, time-frequency processing of the received signal, calculation in each frequency channel formed as a result of time-frequency processing of the received noise signals, complex sound pressure amplitudes, three components of the pressure gradient vector, three components of the vibrational velocity vector, three components of the intensity vector in the local coordinate system associated with the combined receiver, for the total signal plus noise process and for the noise separately, the formation in each frequency channel of an 8-channel static fan of directivity characteristics in horizontal plane, formation in each frequency channel of a 2-channel static fan of directivity characteristics in the vertical plane, calculation for the total process signal plus interference and for interference separately 20 components, real and imaginary, of the intensity vector in 10 spatial channels, calculation of six quadratic components for the vector pressure gradient, five components for the intensity vector rotor and for the squared sound pressure, 16 informative parameters for the horizontal components of the intensity vector rotor, centering and normalization of all 48 informative parameters calculated for the total signal plus noise process, to the corresponding informative parameters calculated for the noise, after which the maximum signal-to-noise ratio is calculated for one of 48 informative parameters, and a detection decision is made by comparing the maximum signal-to-noise ratio calculated for one of 48 informative parameters with the threshold value of the signal-to-noise ratio.

EFFECT: increased noise immunity and range of the receiving system at infrasonic frequencies in shallow sea conditions by using a receiving system that is directional in shallow sea conditions at any arbitrarily low frequencies.

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