82 results about "Sound speed profile" patented technology

The invention discloses a deep sea multibeam sound ray accurate tracking method. The method mainly comprises the steps of (1) establishing a spatial and temporal variation ocean temperature and salinity field model on the basis of the comprehensive analysis of influence factors of sea surface temperature and salinity and with the integration of marine satellites and Argo buoy multiple-source marine physical hydrological observation data, (2) calculating each beam initial incident angle through analyzing the influence of a ship instantaneous attitude on a beam initial incident angle and considering a ship attitude, (3) calculating a sound speed and an inversion sound speed based on an empirical orthogonal function through the spatial and temporal temperature and salinity field at a sound speed profile no-measured area, obtaining the average value of sound speeds obtained by two methods at a corresponding point as the sound speed of the point, and thus calculating a three-dimensional sound speed profile model, (4) constructing an efficient constant gradient sound ray accurate tracking model, and (5) providing a sound ray tracking precision evaluation method. According to the method, the influence of the ship attitude on the beam initial incident angle is considered, the precision of beam footprint coordinates can be greatly improved.

A computer-readable software stored on a storage medium and executed on a computer to perform an integrated sonar simulation, includes a parameter definition code for defining a plurality of parameters of a sonar, target and sonar environment, and a SNR computation code for computing a SNR of the sonar as a function of range to target, based upon the parameters defined by the parameter definition code. The parameters defined by the parameter definition code include ambient noise, volume scattering strength of the sonar environment, sound velocity profile of the sonar, beam patterns of both projector and receiver of the sonar, type of sonar, range resolution of the sonar, number of eigenrays striking the surface and bottom of the sonar environment, number of eigenrays striking the target, ray trajectories to the target, and surface and bottom scattering strength as a function of angle. The software also includes a target strength model generating code for computing scattering from a selected complex target of a stored set of complex target selections, to thereby generate a target strength model for the selected complex target.

It is proposed a method for estimating an inter-node distance between a sender node (A) and a receiver node (B) belonging to a network comprising a plurality of nodes arranged along towed acoustic linear antennas (20a-20e), an acoustic signal being transmitted from the sender node to the receiver node through an underwater acoustic channel. The method comprises a step of estimating the inter-node distance as a function of an estimate of a sound speed profile of the underwater acoustic channel, said sound speed profile depending on depth.

A system and method for determining a sound speed profile of a water column. A free falling sound source is deployed in the water at a known location and time. The sound source transmits acoustic pulses omnidirectionally therefrom at predetermined times after deployment. An acoustic receiver located at a known location detects each acoustic pulse. The time differential between each predetermined time and a time of arrival for each subsequent acoustic pulse is determined. Speed of sound for each portion of the water column is then determined as a function of the time differential, the known locations of sound source deployment and the acoustic receiver, and the known rate of descent of the sound source. The sound source can be constructed from a hydrodynamic body housing a power source, timing electronics, and spark gap electrodes. A bubble, generated by the spark gap electrodes, implodes to create the acoustic pulse.

A system and method for predicting active, low-frequency sonar array performance in shallow, littoral waters using a physics-based modeling of acoustic reverberation. An operator characterizes the active sonar's acoustic transmitter and receiver, the environment it is operating in and the targets to be detected. The operator selects appropriate bathymetry, bottom composition and sound-speed profile. The spatial resolution of the bathymetry database is enhanced using fractal interpolation and a bottom-loss-and-scattering corrected-for-slope is calculated. A semi-empirical scattering strength is derived from a wind-speed data base and a stochastic biologic realization is derived from a biologic population database. These are then used to calculate a deterministic component of bottom, surface and volume reverberation using a normal mode mathematical model of acoustic wave propagation. A stochastic realization of clutter is calculated using a Generalized Gamma distribution database, and combined with the deterministic components of reverberation.

The invention discloses an ocean sound velocity profile acquisition method based on a self-organizing competitive neural network, and relates to the field of ocean sound velocity profiles, which comprises the following steps: firstly, expressing a sample profile of a historical sound velocity profile as a form that average value is added to the orthogonal empirical function vector and then multiplied by the corresponding coefficient An of each order; processing the historical sea surface parameter Xn; forming a sample training vector by the An in the S1 and the historical sea surface parameterXn in the S2; training the sample set by adopting a self-organizing competitive neural network algorithm to form an artificial neuron topological structure; acquiring real-time sea surface parameters, inputting the real-time sea surface parameters into the neuron topological structure, and acquiring An corresponding to the real-time sea surface parameters; and finally, in combination with the historical average sound velocity profile, the EOF vector and the real-time EOF coefficient, expressing the sample profile as an An form to obtain a real-time ocean sound velocity profile. According to the method, the relation between the sound velocity profile contained in the sample data and the sea surface remote sensing parameters is mined through the artificial neural network, and the precisionof the obtained sound velocity profile can be improved.

The invention provides a propagation time measurement method for direct signals based on autonomous underwater vehicles. The invention comprises the steps of: determining a set of measurement time ofdirect signal propagation point in a known task area with to be measured sound speed; placing a sending underwater autonomous vehicle and a receiving underwater autonomous vehicle at the known task area with to be measured sound speed to measure propagation time of direct sound signals through a single-input-multiple-output double direction interaction communication mode; according to the propagation time of direct sound signals, acquiring a sound speed profile by adopting a sound speed profile inversion algorithm which based on a matched field processing technology; and carrying out measurement and sound speed profile inversion on each latitude and longitude coordinate point to construct a sound speed profile set according to the sound speed profile inversion algorithm which based on thematched field processing technology. The method has the advantages that influence of boundary parameter mismatch is reduced, and an approximate error of representing sound speed distribution of the whole area is avoided.

The invention relates to a sound velocity profile completion method based on historical data and machine learning. The method comprises the following steps: obtaining sea area historical average data of a target sea area as first data and historical data collected by instrument equipment as second data; performing EOF analysis on the first data and the second data to obtain an EOF projection coefficient set; taking the second data and the EOF projection coefficient set as training samples for training to obtain neurons representing different reference classification information; obtaining sea area field measured data of a target sea area, and calculating and obtaining a reference neuron with the highest correlation degree with the sea area field measured data; and reconstructing a sound velocity profile according to the reference neurons and the sea area historical average data, and completing sound velocity profile completion of the target sea area. The sound velocity profile reconstruction result established through the method conforms to the disturbance law, the reconstruction result not conforming to the reality is avoided, the characteristics of the small-time-scale sound velocity profile fine structure of the target sea area are included, and the complex disturbance state in the practical situation can be reflected.

The invention provides a flight-crossing type sounding data profile sound velocity correction method combining historical profile sound velocity and actually measured surface sound velocity, and belongs to the technical field of marine surveying and mapping. The method comprises the steps: inputting historical water temperature, salinity and pressure data of a flight-crossing type deep sea measurement area, and calculating sound velocity profile data; carrying out vertical layering of the standardized sound velocity profile; carrying out EOF analysis on a standardized historical sound velocity profile group to obtain a reconstruction coefficient range and a feature vector; constructing a genetic algorithm to optimize a neural network model, and selecting a fitness function; inputting historical sound velocity profile data, and training the model; inputting the actually measured surface sound velocity, the position information, the depth and the feature vector into the trained model, and inverting a sound velocity profile; and carrying out sound velocity correction on the flight-crossing sounding data by adopting constant gradient sound ray tracking. According to the method, the defect that a high-precision sound velocity profile for sound velocity correction is lacked in the post-processing stage of the current flight-crossing type water depth data is overcome, the influence of sound velocity errors is weakened, and the precision of the flight-crossing type sounding data is improved.

The invention provides a gain calculation method for a caustic convergence region under a deep sea complete sound channel based on a ray normal mode theory. The gain calculation method is characterized in that under the deep sea complete sound channel condition, a typical deep sea Munk sound velocity profile situation is analyzed by using a ray normal mode theory, and then an expression of the sound pressure is obtained; the sound intensity is calculated according to the expression of the sound pressure; the average sound intensity value of the energy is calculated in the bandwidth of the 1/3octave of the central frequency; the average propagation loss value of the energy is calculated; the spherical wave propagation loss value at the caustics of the convergence region is calculated; andthe energy average propagation loss value is compared with the spherical wave propagation loss value, so that the gain value at the caustic convergence region is solved, and the result proves that thegain calculation method provided by the invention has a very good effect.

The invention provides an underwater pulse acoustic positioning system based on a multi-acoustic wave glider and a water surface unmanned boat, and relates to the technical field of underwater positioning. In order to solve the problem of communication difficulty in the underwater pulse acoustic positioning based on the multi-acoustic wave glider in the prior art, the underwater pulse acoustic positioning system provided by the invention implements local positioning networking of the multi-acoustic wave glider, determines the number of AWGs and designs an optimal formation of AWGs and USV according to a sea depth, a sound velocity profile and a positioning area required for a task, and monitors and controls the formation of the AWGs through the USV, meanwhile maintains the USV at the central positions of the AWGs to ensure easy and smooth communication, and furthermore, the communication efficiency is high.

The invention relates to a sound ray correction method, in particular to application of a sound ray correction algorithm based on a spatial scale to a long baseline underwater acoustic positioning system. By knowing the depths of a transponder and an underwater target, according to the vertical distance simplification principle, the sound velocity profile is simplified, redundant repeated data which can generate interference are abandoned, data which are obvious in change and have calculation value are reserved, calculation iteration of sound ray correction is greatly reduced, rapid simplification operation is achieved, and the data processing efficiency of sound ray tracking is obviously improved. The simplified sound velocity profile is layered on the spatial scale, and the non-uniform spatial distribution of seawater is further considered, so that the method is more in line with the actual scene.

The invention discloses a sound velocity profile inversion method based on an over-complete dictionary, and the method comprises the steps: 1), constructing a non-orthogonal and over-complete dictionary D of a sound velocity profile based on a K-SVD algorithm according to historical data; 2) linearizing the nonlinear response of the forward model by using a first-order Taylor expansion, and creating a measurement matrix Q; 3) laying a single sound source and a vertical array in a sea area to be measured, and transmitting and receiving signals; 4) based on an OMP algorithm, inverting a sparse coefficient vector X of the over-complete dictionary atoms; and 5) calculating the sound velocity profile according to the time-varying non-orthogonal dictionary atomic coefficient obtained by inversion. Compared with a method based on an empirical orthogonal function, the method is based on an over-complete dictionary, the intrinsic characteristics of the sound velocity profile can be better captured through redundancy characteristics, and the inversion precision of the sound velocity profile is greatly improved.

The invention belongs to the technical field of marine acoustics application of three-dimensional temperature-salinity-depth data, and particularly relates to a high-resolution sound velocity profile data compression method based on empirical orthogonal function decomposition. The method specifically comprises the following steps of providing data by using a high-resolution marine reanalysis product, and converting by using a sound velocity formula to obtain the seawater sound velocity profile data; according to the characteristics of the technical field of marine acoustics application, extending the high-resolution and long-time sequence sound velocity profile data under a certain space-time dimension to a seabed sedimentary layer; using a feature vector of a main mode as a primary function of the sound velocity profile empirical orthogonal function decomposition, and compressing and expressing the high-resolution and long-time sequence sound velocity profile information under the certain space-time dimension. According to the invention, the technical scheme of obtaining sound velocity profile data compression from a high-resolution ocean reanalysis product is realized; the effective compression of the sound velocity profile data under the certain time-space dimension is realized, and the beneficial effect that the compression rate of the high resolution and long-time sequence sound velocity profile data is more than 90%, is obtained.

The invention belongs to the fields of physical ocean, ocean technology, underwater acoustic engineering and the like, and particularly relates to an ocean front reconstruction method based on K-means algorithm iterative hierarchical clustering of sound velocity profiles, and the method uses the K-means algorithm to perform hierarchical clustering on the sound velocity profiles of an ocean front sea area according to a hierarchical principle. Compared with other clustering algorithms, the method is simple in thought, high in convergence speed, good in clustering effect and capable of meeting the clustering requirement when a large number of sound velocity profiles exist in the ocean front sea area. And the accuracy of the clustering result can be verified through the calculation of the sound propagation loss, and the iterative optimization is provided for the hierarchy according to the error threshold until all the hierarchical clustering results meet an allowable error threshold, and finally the ocean front reconstruction based on K-means algorithm iterative hierarchical clustering of sound velocity profiles is realized.

The invention discloses an OBS precise positioning method based on underwater acoustic ranging and multi-beam terrain. Firstly, an acoustic communication machine is used to measure the distance of theOBS within the effective range of the OBS delivery point; when the sound velocity profile is not considered, the nonlinear equations are constructed by the relationship between the slant distance from the OBS to the ranging point and the travel time, and the bottom position of the OBS is obtained by solving the equations with Newton iterative algorithm; when the sound velocity profile is considered, the multi-beam seabed terrain near the OBS delivery point is gridded, according to the sound velocity profile, the calculated travel time between each grid point and the ranging point is calculated by using the ray tracing method, and the residual equations for calculated travel time and observed travel time between OBS and each ranging point are constructed; the grid search method is used tosolve the optimal solution of the residual equations, that is, the bottom position of the OBS. The method of the invention has the characteristics of simple operation, time-saving and accurate calculation, and realizes the accurate positioning of the OBS seabed for free falling body dropping.

The invention provides a target detection method in a deep sea incomplete sound channel, and relates to the technical field of submarine incomplete sound channel underwater acoustic detection, and themethod comprises the steps: obtaining the relation between the sound ray horizontal distance and depth under a specific sound velocity profile based on a ray simple positive wave, and enabling a marine environment to be an incomplete sound channel, i.e., the submarine sound velocity is smaller than the sea surface sound velocity; according to the determined relationship between the sound ray horizontal distance and the depth, obtaining a point of a sound ray minimum value position, and determining the position of a lower reversal point convergence area; selecting a plurality of hydrophones toform a multi-element vertical receiving array, arranging the multi-element vertical receiving array in a lower reversal point convergence area, and detecting a long-distance target to obtain a detection signal; and determining whether the detection target exists or not according to a detection signal obtained by detecting the long-distance target. According to the invention, large-depth arrayingis carried out in an incomplete sound channel by using the lower inversion point convergence region, so that the detection of a target is realized.

The invention discloses a sound velocity profile (SVP) streamlining and optimization method based on maximum offset of velocity, and provides detailed comprehensive technical process so as to solve the problem that the work efficiency of multi-beam detection and data processing are seriously influenced because the original sound velocity profile has a large data quantity. An MOV method is provided and is used for deleting the redundant points automatically and quickly, and for evaluating the influence of the streamlined sound velocity profile on precision of multi-beam sounding through ray tracing and error analysis. The method has an important actual application value in the aspects of marine surveying and charting, multi-beam surveying, a marine geographic information system, computer graphics, submarine science research and the like, and can be popularized.

The invention provides an underwater control point positioning method considering surface acoustic velocity and the coordinate prior information and belongs to the technical field of underwater positioning. According to the method, surface acoustic velocity and coordinate prior information are considered, acoustic velocity errors of a circular sailing method and acquisition of control point planecoordinate prior information are analyzed, control point coordinates and a water depth value measured by a pressure sensor are regarded as random quantities, and a water depth observation value is endowed with a first empirical variance which is 0.1% of the water depth according to experience; and finally, coordinates of the control points are solved by adopting a generalized least square principle. Simulation of 50m and 1500m water depth positioning experiments proves that under the condition of not using a sound velocity profile, only surface sound velocity and coordinate prior information are considered, a high-precision positioning result can also be obtained, the ship hour can be effectively saved, and operation efficiency is improved. The method is high in practicability, stable andreliable in result and high in efficiency, and is mainly used for transmitting the absolute coordinate reference of the underwater control network.

The invention discloses an integrated acoustic positioning and tracking control method for an autonomous underwater vehicle. According to the method, three buoys for emitting periodic acoustic signals are arranged on the water surface, and the position of the AUV is estimated according to the time when the three signals reach the AUV and the sound velocity profile. Meanwhile, system uncertainty caused by position estimation and ocean current interference is processed through extended Kalman filtering; in order to effectively process physical constraint conditions of an AUV system and achieve a certain optimal tracking effect, an AUV hydrodynamic model is considered, and a path tracking model predictive control (MPC) device is designed. Because positioning and control have different sampling time, track plotting is carried out on the control time step of silent mechanical positioning information by using an AUV nominal model. In consideration of the real-time performance of the algorithm, a continuous linearization method under an MPC framework is adopted to carry out approximate processing on a system model, and the balance between the control effect and the calculation efficiency is obtained.