SONAR METHOD FOR DETECTING UNDERWATER OBJECTS IN CONTROLLED WATER AREA Russian patent published in 2016 - IPC G01S15/02 

FIELD: acoustics.

SUBSTANCE: invention relates to hydroacoustics and is intended for automatic detection of slow-moving objects. Sonar method for detection of underwater objects in controlled water area, wherein water space is successively irradiated with signals, echo signals are received from objects as static fan of directivity characteristics, are digitised by distance, displayed on two-dimensional indicator at first radiation-reception cycle, at first distance elements of all spatial directions M, interference is determined and threshold selected, in each spatial channel by all elements of distance L, echo signal amplitudes are compared with threshold, and amplitude exceeding threshold and time exceeding of threshold are determined, maximum amplitude of reading exceeding threshold is determined, time differences between beginning of element L_p, where p is number of distance element, in which echo signal was detected, and time position of maximum amplitude Δt_max1 is determined, number N of readings in interval L_p, exceeding threshold is determined, radial length ΔS of object in distance element L_p by formula ΔS=(t_N-t₁)C is determined, where t_N is time of last reading exceeding threshold, t₁ is first reading exceeding threshold in selected interval, C is speed of sound propagation; measured parameters are stored, following radiation-reception cycle is performed, measurement procedure is repeated, those directions M and those distance elements L are determined, which coincide in first and second radiation-reception cycles, radial velocity of object is determined by formula V_rad= (Δt_2max-Δt_1max) C/ΔT_k, where ΔT_k is interval between radiation-reception cycles, Δt_2max is interval between time position of maximum and time of beginning distance element of second radiation-reception cycle, results classification display is formed based on measured parameters: direction of M_i, in which detection occurred, number of distance element L_p, number of cases exceeding threshold of N, radial length ΔS, radial velocity V_rad, Automatic decision is made if ΔS < L_p, that object is small-sized, if V_rad= 0, decision is made, that object is fixed, if V_rad≠0, decision is made, that object is slow-moving, and operator can make decision on class of low-moving, small-size object based on analysis of measured parameters.

EFFECT: automatic detection of slow-moving objects.

1 cl, 1 dwg