METHOD FOR RECORDING LOW NOISE MARINE OBJECT BY USING MEDIAN FILTERING Russian patent published in 2017 - IPC G01S15/04 

FIELD: physics.

SUBSTANCE: method for recording a low noise marine object by using the median filtering is that the "reference" amplitude-frequency characteristic (AFC) of the aqueous space noise field is first recorded in the receiving devices. Thereafter, its filtering and analog-to-digital converting are performed in the primary signal processing unit. Further, the "reference" AFC is used to determine the pair of the receiving devices in the unit for calculating the cross-correlation function and deciding the secondary signal processing unit, and then is fed to the respective inputs of the adaptive filter of the secondary signal processing unit, where the "normalized" AFC of the space noise of the protected aqueous space is produced. The "operating" AFC of the aqueous space is generated, when there is a low-noise marine object in the protected aqueous space in the area, where the receiving devices are located, which is transmitted to the first input of the unit for calculating and deciding the cross-correlation function and the first input of the adaptive filter of the secondary signal processing unit, via the preselected first receiving channel. The AFC of the low-noise marine object is recorded, when the amplitude of the "operating" AFC of the aqueous space exceeds the generated threshold of the normalised AFC. The principal difference of the claimed invention is that the claimed method, implemented in the proposed device for recording the low noise marine object by using the median filter after analog-to-digital converting in the receiving channels of the primary signal preprocessing unit, further comprises median filtering by using the appropriate identical median filters, whereby it is possible to suppress the impulsive noise and random emissions in the signal processing path, that can significantly improve the noise immunity when recording the low noise marine object.

EFFECT: method for recording the noise emission of the low noise marine object in a broad frequency band by using median filtering, which can be used in the measurement of the primary hydroacoustic field of the low noise marine objects in the presence of the impulse noise, random emissions in the signal processing path, elevated level and non-stationary background noise within the time recording the marine object passage.

5 dwg