METHOD OF DETECTING LOW-NOISE MARINE OBJECT Russian patent published in 2015 - IPC G01S15/04 

FIELD: physics.

SUBSTANCE: method of detecting a low-noise marine object includes first detecting in receiving devices the "reference" amplitude-frequency response of the noise field of a water area for subsequent processing in a primary signal processing unit in order to determine pairs of receiving devices in a decision-making and cross-correlation function computing unit of a secondary signal processing unit; transmitting the "reference" amplitude-frequency response to corresponding inputs of an adaptive filter of the secondary signal processing unit, where the "normalised" amplitude-frequency response of the noise field of a secure water area is generated; when a low-noise marine object appears in the secure water area in the region where the receiving devices are located, generating the "operating" amplitude-frequency response of the water area, which is transmitted via a preselected first receiving channel to the first input of the decision-making and cross-correlation function computing unit and the first input of the adaptive filter of the secondary signal processing unit; when the amplitude of the "operating" amplitude-frequency response of the water area exceeds the generated threshold of the normalised amplitude-frequency response, recording the amplitude-frequency response of the low-noise marine object. The fundamental distinction of the present invention is that the disclosed method, which is realised in the disclosed apparatus for detecting a low-noise marine object, further employs a decision-making and cross-correlation function computing unit, as well as an adaptive filter, based on the principle of minimisation of the root-mean-square error of interference, which enables to suppress transient interference with a short correlation interval relative to the arrival time of the marine object, which improves noise-immunity when detecting a low-noise marine object.

EFFECT: high accuracy and shorter time for analogue-to-digital conversion, use in measuring the primary hydroacoustic field of low-noise marine objects in conditions with high level and transience of background noise within the detection time of the arrival of the marine object, as well as use in security devices for protecting off-shore areas, port and other structures.

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