Acoustic buoy array-based near water surface supersonic speed target detection method and system

Abstract

The invention belongs to the technical field of acoustic signal detection, and discloses a near water surface supersonic speed target detection method and system based on an acoustic buoy array. The method comprises the following steps: firstly, constructing a cross-air-sea medium attenuation prediction model, and realizing matching of near-water-surface supersonic target radiation noise in underwater propagation signals; secondly, automatically selecting an acoustic buoy alarm unit by adopting a maximum energy and minimum spacing method, expanding measurement information by utilizing an alarm buoy unit combined positioning technology, and eliminating background noise and interference outside a combined positioning area to obtain to-be-processed information; thirdly, selecting a to-be-processed information fragment by using the TBD, and performing Hough transformation processing on the to-be-processed information fragment to obtain an initial trace point set of a target, noise and interference meeting the requirement of track approximate linear motion; and finally, setting motion elements such as speed, acceleration, course angle and course angle change rate to perform constraint processing on the initial trace point set, eliminating noise and interference trace points, obtaining a real track of the target, and completing detection of the near water surface supersonic target.

Description

Technical Field

[0001] The present invention relates to the field of acoustic signal detection, and in particular to a method and system for detecting supersonic targets near a water surface based on an acoustic buoy array. Background Art

[0002] Supersonic targets near the water surface move fast and sail at low altitudes, which greatly increases the success rate of their ultra-low altitude raids on surface ships. In view of the serious threat posed by such targets to the safety of surface ships, domestic and foreign researchers and technicians mainly use shipborne radars to detect them and achieve advance warnings. However, shipborne radar detection is limited by the curvature of the earth and the target echo signal is easily interfered by sea clutter, which restricts the detection area and detection probability, resulting in poor warning timeliness and high subsequent interception cost-effectiveness. In order to achieve supersonic flight, supersonic targets near the water surface require a high-power propulsion system. During the launch phase, the navigation phase before entering the water surface, the navigation phase near the water surface, and after hitting the surface ship, it will generate huge radiation noise. Existing literature only studies the detection of this radiation noise by acoustic sensors in the air. The propagation speed of sound waves in the air is about Mach 1 (340 meters per second), but the movement speed of supersonic targets near the water surface is greater than this value, and acoustic sensors cannot achieve effective advance warnings for them. When sound waves are transmitted from air to water, the propagation speed will be greatly increased, and the propagation speed in water is about 1500 meters per second (close to Mach 4.4). Therefore, taking advantage of the speed of sound propagation in water, underwater acoustic sensors are used to detect the radiation noise of targets entering the water from the air, making it possible to use acoustic sensors for early warning of supersonic targets near the water surface.

[0003] As one of the underwater application types of acoustic sensors, acoustic buoys are widely used in the fields of ocean forecasting, environmental monitoring, underwater detection, etc. Acoustic buoys can be carried on different platforms on land, sea and air, and the deployment method is flexible; they can be passively detected and have good concealment; they are far away from the deployment platform and are less disturbed by platform noise. However, when propagating from air to water, the physical properties of the target radiated noise will change significantly, especially the energy will decay rapidly. The background noise and interference generated by natural environments such as thunderstorms, wind and waves, marine animals such as dolphins and shrimps, and underwater and surface vehicles in working state can easily drown out the weak target radiation noise. In addition, it is difficult for a single acoustic buoy to obtain target signals and achieve reliable detection.

[0004] TBD theory and Hough transform are one of the hot research directions of weak target detection. They are widely used in the detection of weak targets such as near-space ultra-high-speed vehicles and vehicles in complex underwater acoustic environments. They have technical advantages, especially in the detection of targets that move approximately in a straight line. Focusing on the problems of passive detection of supersonic targets near the water surface, by analyzing the radiation noise of supersonic targets near the water surface and the characteristics of air-sea medium, a cross-air-sea medium attenuation prediction model is constructed, and the acoustic buoy warning array is reasonably arranged to carry out detection preprocessing. The TBD theory and Hough transform are used to process the measurement information to be detected, so as to achieve effective detection of supersonic targets near the water surface. Summary of the invention

[0005] The present invention proposes a method for detecting supersonic targets near the water surface based on an acoustic buoy array, so as to break the limitation that supersonic targets near the water surface mainly rely on electromagnetic wave detection, solve the influence of weak target signal after attenuation through cross-air-sea medium propagation, strong background noise and interference, and weak sonar detection capability of a single buoy, thereby expanding the adaptability of TBD theory and Hough transform technology and the feasibility of passive detection of supersonic targets near the water surface by an acoustic buoy array.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for detecting supersonic targets near the water surface based on an acoustic buoy array, comprising:

[0008] Step 1: Construct a cross-air-sea medium attenuation prediction model to match the radiation noise of the near-surface supersonic target with the underwater propagation signal; the movement speed of the near-surface supersonic target does not exceed Mach 4;

[0009] Step 2: Automatically select the acoustic buoy warning unit using the maximum energy and minimum spacing method, use the warning buoy unit joint positioning technology to expand the measurement information, and eliminate the background noise and interference outside the joint positioning area to obtain the information to be processed; the acoustic buoy is a passive buoy sonar with direction finding function;

[0010] Step 3: Use TBD theory to select the information fragments to be processed, perform Hough transform on the information fragments to be processed, and eliminate most of the background noise and interference to obtain the initial point track set of the target, noise and interference that meets the approximate linear motion of the track;

[0011] Step 4: Set the motion elements such as velocity, acceleration, heading angle and heading angle change rate to constrain the initial point track set, eliminate noise and interference points, and obtain the true track of the target, thus completing the detection of supersonic targets near the water surface.

[0012] Optionally, step one specifically includes:

[0013] Assume that the supersonic target near the water surface moves approximately in a straight line. The supersonic target radiation noise has sound energy attenuation during the propagation process across the air-sea medium. Considering the influence of factors such as sound speed, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, underwater sound propagation refractive index, Doppler frequency shift, etc., a prediction model of sound energy attenuation across the air-sea medium is constructed to realize the prediction of the energy change of the radiation noise of the supersonic target near the water surface when it enters the water from the air. The predicted value of energy change at time k is

[0014] e as(k) =F(v (k) ,p r(k) ,t h(k) ,r e(k) ,Δf (k) ,r d(k) ,l vh(k) )

[0015] Where: v is the speed of sound, r d is the attenuation rate, l vh is the viscosity and heat loss, p r is the Prandtl number, t h is the boundary layer thickness, r e is the refractive index of underwater sound propagation, and Δf is the Doppler frequency shift.

[0016] Optionally, step 2 specifically includes:

[0017] Assume that each sonar in the acoustic buoy warning array has the same performance and synchronized data. Within the detection range of the warning array, the acoustic buoy warning unit is determined based on the maximum signal energy and the minimum adjacent spacing by detecting the measured energy obtained by each acoustic buoy. Assume that the acoustic buoy warning array consists of N passive direction-finding sonar buoys with adjacent spacing d. In the coordinate system Oxy, the buoy position coordinates are (x si ,y si )(i=1,2,…,N), the measurement data set of the ith acoustic buoy at time k is Z i ={z ki |k=1,2,…,K}. The data set received by the ith acoustic buoy at time k is

[0018] z ki ={(α k(i)j ,e k(i)j )|j=1,2,…,n j}

[0019] Where: n j is the number of measurements, α k(i)j is the azimuth of the jth measurement, e k(i)j is the energy of the jth measurement.

[0020] The energy set measured by the i-th acoustic buoy at time k is:

[0021] {e k(i)j |i=1,2,…,N,j=1,2,…,n j}

[0022] According to the azimuth angle of the passive acoustic buoy receiving the measurement, the energy of the jth measurement of the ith acoustic buoy at time k is

[0023] e k(i)j ∈{e as(kij) ,e no(kij) ,e jim(kij)}(i=1,2,…,N,j=1,2,…,n j )

[0024] Where: e as(kij) is the target energy value, e no(kij) is the energy value of the background noise, e jim(kij) is the energy value of the interference.

[0025] The maximum value method is used to search for the maximum energy value, and the corresponding acoustic buoy is i * .

[0026]

[0027] Where: The decision threshold is N s / 2,N s is the number of buoys in the acoustic buoy warning array, and N is the buoy accumulation matrix.

[0028] According to the maximum energy value formula, we further search the acoustic buoy warning array and obtain two buoys with the next maximum energy value i1 * and i2 * .

[0029] Using the minimum spacing method to search for buoy i * With buoy i1 * and buoy i2 * The corresponding acoustic buoy is i ** .

[0030] r(i * ,i ** )=min{r(i * ,i1 * ),r(i * ,i2 * )}

[0031] Where: r(i * ,i1 * ) is the buoy i * With buoy i1 *The spacing, r(i * ,i2 * ) is the buoy i * With buoy i2 * spacing.

[0032] The acoustic buoy warning unit is (i * ,i ** ).

[0033] In the plane coordinate system Oxy, the warning buoy unit (i * ,i ** ) Get measurement information z ki (i=i * ,i ** ), using joint positioning technology to obtain measurements containing position information (x k(i*)j ,y k(i*)j ,e k(i*)j ), and eliminate background noise and interference outside the joint positioning area to achieve measurement information expansion.

[0034] Optionally, step three specifically includes:

[0035] The TBD theory is used to select the information fragments to be processed. According to the time sequence, the measurement information within K (5≤K≤7) consecutive moments is randomly selected to obtain the measurement point set Z to be detected. k In the coordinate system Oxy, the set of measurement points at time k is

[0036] Z k ={(x i*k ,y i*k ,e i*k )}(k=1,…,K).

[0037] Construct data space A={Z1,…,Z K}, parameter space B, accumulation matrix D and energy accumulation matrix E, and initialize B, D and E.

[0038] A and B are subjected to random Hough transform detection, and most of the background noise and interference are eliminated to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track. The double threshold accumulation formula of the number of points and energy is:

[0039]

[0040] Where: (θ t ,ρ m ) represents the coordinates of the center points of each parameter unit in B, and “+=” represents the accumulation operation;

[0041] If the initial point trace does not exist, repeat steps

[0035] -

[0038] .

[0042] Optionally, step 4 specifically includes:

[0043] If the detected point trace in step 3 exists, then perform point trace constraint processing, select any adjacent data points at time k, k+1, k+2 in the initial point trace, calculate the motion elements such as speed, acceleration, heading angle and heading angle change rate, and constrain the initial point trace. For example, in the coordinate system Oxy, the speed constraint condition is

[0044]

[0045] Where: v xmax is the maximum velocity in the x direction, v ymax is the maximum velocity in the y direction, v k is the speed value in the predicted value of energy change.

[0046] According to prior information such as the predicted value of acoustic energy attenuation, the initial point traces that meet the constraints are merged, and the initial point traces that do not meet the constraints are eliminated, the noise and interference point traces are eliminated, and the target point traces with high fitting degree are obtained, thus completing the detection of supersonic targets near the water surface.

[0047] The present invention also provides a near-surface supersonic target detection system based on an acoustic buoy array, the system comprising:

[0048] The cross-air-sea medium acoustic energy attenuation prediction module uses the radiation noise of supersonic targets near the water surface and the characteristics of air-sea media to construct a cross-air-sea medium attenuation prediction model to achieve the matching of the radiation noise of supersonic targets near the water surface with the underwater propagation signal; the movement speed of supersonic targets near the water surface does not exceed Mach 4.

[0049] The acoustic buoy warning unit processing module determines the formation, buoy spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship and the meteorological and hydrological conditions. After the acoustic buoy receives the hydroacoustic signal, it transmits it back to the underwater acoustic signal processing system via radio equipment. The maximum energy and minimum spacing method is used to automatically select the acoustic buoy warning unit, and the warning buoy unit joint positioning technology is used to expand the measurement information, and the background noise and interference outside the joint positioning area are eliminated to obtain the information to be processed. The acoustic buoy is a passive buoy sonar with direction-finding function.

[0050] The TBD and Hough transform processing module uses the TBD theory to select the information fragments to be processed, performs Hough transform processing on the information fragments to be processed, and eliminates most of the background noise and interference to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track.

[0051] The point track constraint processing module calculates motion elements such as velocity, acceleration, heading angle and heading angle change rate, and performs constraint processing on the initial point track to eliminate noise and interference point tracks to obtain the true track of the target, thereby completing the detection of supersonic targets near the water surface.

[0052] Optionally, the cross-air-sea medium acoustic energy attenuation prediction module specifically includes:

[0053] The cross-air-sea medium sound energy attenuation prediction unit considers the influence of factors such as sound velocity, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, underwater sound propagation refractive index, Doppler frequency shift, etc., and constructs a cross-air-sea medium sound energy attenuation prediction model;

[0054] Assume that the supersonic target near the water surface moves approximately in a straight line. The sound energy of the supersonic target radiation noise will attenuate during the propagation process across the air-sea medium. The predicted value of the sound energy attenuation of the supersonic target radiation noise near the water surface after entering the water from the air at time k is

[0055] e as(k) =F(v (k) ,p r(k) ,t h(k) ,r e(k) ,Δf (k) ,r d(k) ,l vh(k) )

[0056] Where v is the speed of sound, r d is the attenuation rate, l vh is the viscosity and heat loss, p r is the Prandtl number, t h is the boundary layer thickness, r e is the refractive index of underwater sound propagation, and Δf is the Doppler frequency shift.

[0057] Optionally, the acoustic buoy warning unit processing module specifically includes:

[0058] The acoustic buoy warning array deployment unit determines the formation, buoy spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship, as well as the meteorological and hydrological conditions; the acoustic buoy is a passive buoy sonar with direction-finding function.

[0059] Assume that the acoustic buoy warning array consists of N passive direction-finding sonar buoys with adjacent spacing d. In the coordinate system Oxy, the buoy position coordinates are (x si ,y si )(i=1,2,…,N), the measurement data set of the ith acoustic buoy at time k is Z i ={z ki |k=1,2,…,K}. The data set received by the ith acoustic buoy at time k is

[0060] z ki ={(α k(i)j ,e k(i)j )|j=1,2,…,n j}

[0061] Among them, n j is the number of measurements, α k(i)j is the azimuth of the jth measurement, e k(i)j is the energy of the jth measurement.

[0062] Optionally, the energy set measured by the i-th acoustic buoy at time k is

[0063] {e k(i)j |i=1,2,…,N,j=1,2,…,n j}

[0064] Optionally, the energy of the jth measurement of the ith acoustic buoy at time k is

[0065] e k(i)j ∈{e as(kij) ,e no(kij) ,e jim(kij)}(i=1,2,…,N,j=1,2,…,n j )

[0066] Among them, e as(kij) is the target energy value, e no(kij) is the energy value of the background noise, e jim(kij) is the energy value of the interference.

[0067] The acoustic-to-electric conversion and signal feedback unit receives the underwater acoustic signal and transmits it back to the underwater acoustic signal processing system via radio equipment.

[0068] The acoustic buoy alarm selection unit uses the maximum energy and minimum spacing method to automatically select the acoustic buoy alarm unit.

[0069] Optionally, the maximum value method is used to search for the maximum energy value, and the corresponding acoustic buoy is i * .

[0070]

[0071] Among them, the decision threshold is N s / 2,N s is the number of buoys in the acoustic buoy warning array, and N is the buoy accumulation matrix.

[0072] According to the maximum energy value formula, we further search the acoustic buoy warning array and obtain two buoys with the next maximum energy value i1 * and i2 *.

[0073] Optionally, use the minimum spacing method to search for buoy i * With buoy i1 * and buoy i2 * The corresponding acoustic buoy is i ** .

[0074] r(i * ,i ** )=min{r(i * ,i1 * ),r(i * ,i2 * )}

[0075] Among them, r(i * ,i1 * ) is the buoy i * With buoy i1 * The spacing, r(i * ,i2 * ) is the buoy i * With buoy i2 * spacing.

[0076] The acoustic buoy warning unit is (i * ,i ** ).

[0077] The joint positioning hydroacoustic signal unit uses the alarm buoy unit to jointly position the hydroacoustic signal, and eliminates background noise and interference outside the joint positioning area to obtain the information to be processed.

[0078] In the plane coordinate system Oxy, the warning buoy unit (i * ,i ** ) Get measurement information z ki (i=i * ,i ** ), using joint positioning technology to obtain measurements containing position information (x k(i*)j ,y k(i*)j ,e k(i*)j ), and eliminate background noise and interference outside the joint positioning area to achieve measurement information expansion.

[0079] Optionally, the TBD and Hough transform processing module specifically includes:

[0080] The TBD and Hough transform processing module uses the TBD theory to select the information fragments to be processed, performs Hough transform processing on the information fragments to be processed, and eliminates most of the background noise and interference to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track.

[0081] TBD selects the information fragment unit to be processed, and uses TBD theory to randomly select the measurement information within K (5≤K≤7) consecutive moments in time sequence to obtain the measurement point set Z to be detected. k In the coordinate system Oxy, the set of measurement points at time k is

[0082] Z k ={(x i*k ,y i*k, e i*k )}(k=1,…,K).

[0083] The Hough transform processing unit performs Hough transform processing on the information fragment to be processed and eliminates most of the background noise and interference to obtain an initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track.

[0084] Construct data space A={Z1,…,Z K}, parameter space B, accumulation matrix D and energy accumulation matrix E, and initialize B, D and E.

[0085] A and B are detected by random Hough transform, and most of the background noise and interference are eliminated to obtain the initial point track set of target, noise and interference that meets the requirement of approximate linear motion of the track.

[0086] Optionally, the dual threshold accumulation formula for points and energy is

[0087]

[0088] Among them, (θ t ,ρ m ) represents the coordinates of the center points of each parameter unit in B, and “+=” represents the accumulation operation;

[0089] If the initial point does not exist, repeat steps

[0081] -

[0085] .

[0090] Optionally, the point trace constraint processing module specifically includes:

[0091] The point trace constraint processing module performs point trace constraint processing if the point trace detected in the TBD and Hough transform processing modules exists. It selects data points at any adjacent k, k+1, and k+2 moments in the initial point trace, calculates motion elements such as velocity, acceleration, heading angle, and heading angle change rate, and performs constraint processing on the initial point trace.

[0092] Speed ​​constraint processing unit, in the coordinate system Oxy, the speed constraint condition is

[0093]

[0094] Among them, v xmaxis the maximum velocity in the x direction, v ymax is the maximum velocity in the y direction, v k is the speed value in the predicted value of energy change.

[0095] Acceleration constraint processing unit, the acceleration constraint condition is

[0096]

[0097] Heading angle constraint processing unit, the heading angle constraint condition is

[0098]

[0099] Heading angle change rate constraint processing unit, the heading angle change rate constraint condition is

[0100]

[0101] According to prior information such as the predicted value of acoustic energy attenuation, the initial point traces that meet the constraints are merged, and the initial point traces that do not meet the constraints are eliminated, the noise and interference point traces are eliminated, and the target point traces with high fitting degree are obtained, thus completing the detection of supersonic targets near the water surface.

[0102] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: a method and system for detecting supersonic targets near the water surface based on an acoustic buoy array provided by the present invention includes: constructing a cross-air-sea medium attenuation prediction model to achieve matching of the radiation noise of supersonic targets near the water surface with the underwater propagation signal; the movement speed of supersonic targets near the water surface does not exceed Mach 4; the acoustic buoy warning unit is automatically selected by the maximum energy and minimum spacing method; the water acoustic signal is jointly positioned by the warning buoy unit to obtain a set of measurement points to be detected; the acoustic buoy is a passive buoy sonar with a direction-finding function; the set of measurement points to be detected is processed by TBD and Hough transform to obtain an initial point track set; if the initial point track set exists, it is constrained to obtain the target's true track, thereby realizing detection of supersonic targets near the water surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0104] Figure 1 A schematic flow chart of a method for detecting supersonic targets near the water surface based on an acoustic buoy array provided in Example 1 of the present invention;

[0105] Figure 2 A flowchart of the implementation of the method for detecting supersonic targets near the water surface based on an acoustic buoy array provided in Example 1 of the present invention;

[0106] Figure 3 A schematic diagram of the construction principle of the cross-air-sea medium attenuation prediction model provided in Example 1 of the present invention;

[0107] Figure 4 A schematic diagram of the automatic selection of an acoustic buoy alarm unit provided in Example 1 of the present invention;

[0108] Figure 5 A schematic diagram of the joint positioning principle of the acoustic buoy warning unit provided in Example 1 of the present invention;

[0109] Figure 6 A flow chart of the TBD and Hough transform algorithm provided in Example 1 of the present invention;

[0110] Figure 7 A diagram of a point trace constraint processing method provided in Example 1 of the present invention;

[0111] Figure 8 A block diagram of a near-surface supersonic target detection system based on an acoustic buoy array provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0112] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0113] The shortcomings of the prior art acoustic buoy in detecting supersonic targets near the water surface mainly include:

[0114] Traditional acoustic sensors are only used to detect aerial targets below Mach 1.

[0115] Since the propagation speed of sound waves in the air is lower than the speed of supersonic targets near the water surface, TBD theory and Hough transform technology cannot be directly used for the detection of supersonic targets near the water surface.

[0116] In view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method and system for detecting supersonic targets near the water surface based on an acoustic buoy array, so as to expand the application of acoustic buoys, TBD theory and Hough transform technology in the field of supersonic target detection near the water surface.

[0117] Example 1

[0118] Example 1 provides a method for detecting supersonic targets near the water surface based on an acoustic buoy array. Figure 1 and Figure 2 , the method comprising:

[0119] Step 1: Construct a cross-air-sea medium attenuation prediction model to match the radiation noise of the near-surface supersonic target with the underwater propagation signal; the movement speed of the near-surface supersonic target does not exceed Mach 4;

[0120] Step 2: Use the maximum energy and minimum spacing method to automatically select the acoustic buoy warning unit, use the warning buoy unit joint positioning technology to expand the measurement information, and eliminate background noise and interference outside the joint positioning area to obtain the information to be processed; the acoustic buoy is a passive buoy sonar with direction finding function.

[0121] Step 3: Use TBD theory to select the information fragments to be processed, perform Hough transform on the information fragments to be processed, and eliminate most of the background noise and interference to obtain the initial point track set of the target, noise and interference that meets the approximate linear motion of the track;

[0122] Step 4: Calculate the velocity, acceleration, heading angle, and heading angle change rate and other motion elements to constrain the initial point track set, eliminate noise and interference points, and obtain the true track of the target, thus completing the detection of supersonic targets near the water surface.

[0123] The following is an introduction to the process of constructing the cross-air-sea medium attenuation prediction model in this embodiment:

[0124] like Figure 3 As shown in the figure, it is assumed that the supersonic target near the water surface moves approximately in a straight line. The radiated noise of the supersonic target has sound energy attenuation during the propagation across the air-sea medium. A general model of the radiated noise of the supersonic target near the water surface is constructed. The influence of factors such as sound speed, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, underwater sound propagation refractive index, Doppler frequency shift, etc. is considered, the sound wave attenuation coefficient is calculated, and a prediction model of sound energy attenuation across the air-sea medium is constructed to realize the prediction of the energy change of the radiated noise of the supersonic target near the water surface when it enters the water from the air. The predicted value of the energy change at time k is

[0125] e as(k) =F(v (k) ,p r(k) ,t h(k) ,r e(k) ,Δf (k) ,r d(k) ,l vh(k) ) (1)

[0126] Where: v is the speed of sound, r d is the attenuation rate, l vhis the viscosity and heat loss, p r is the Prandtl number, t h is the boundary layer thickness, r e is the refractive index of underwater sound propagation, and Δf is the Doppler frequency shift.

[0127] In this embodiment, see Figure 4 , the composition of the acoustic buoy alarm unit automatically selected in step 2 is introduced:

[0128] Assume that each sonar in the acoustic buoy warning array has the same performance and synchronized data. Within the detection range of the warning array, the acoustic buoy warning unit is determined based on the maximum signal energy and the minimum adjacent spacing by detecting the measured energy obtained by each acoustic buoy. Assume that the acoustic buoy warning array consists of N passive direction-finding sonar buoys with adjacent spacing d. In the coordinate system Oxy, the buoy position coordinates are (x si ,y si )(i=1,2,…,N), the measurement data set of the ith acoustic buoy at time k is Z i ={z ki |k=1,2,…,K}. The data set received by the ith acoustic buoy at time k is

[0129] z ki ={(α k(i)j ,e k(i)j )|j=1,2,…,n j} (2)

[0130] Where: n j is the number of measurements, α k(i)j is the azimuth of the jth measurement, e k(i)j is the energy of the jth measurement.

[0131] The energy set measured by the i-th acoustic buoy at time k is:

[0132] {e k(i)j |i=1,2,…,N,j=1,2,…,n j} (3)

[0133] According to the azimuth angle of the passive acoustic buoy receiving the measurement, the energy of the jth measurement of the ith acoustic buoy at time k is

[0134] e k(i)j ∈{e as(kij) ,e no(kij) ,e jim(kij)}(i=1,2,…,N,j=1,2,…,n j ) (4)

[0135] Where: e as(kij) is the target energy value, eno(kij) is the energy value of the background noise, e jim(kij) is the energy value of the interference.

[0136] See Figure 5 , the maximum value method is used to search for the maximum energy value, and the corresponding acoustic buoy is i * .

[0137]

[0138] Where: The decision threshold is N s / 2,N s is the number of buoys in the acoustic buoy warning array, and N is the buoy accumulation matrix.

[0139] According to the maximum energy value formula, we further search the acoustic buoy warning array and obtain two buoys with the next maximum energy value i1 * and i2 * .

[0140] Using the minimum spacing method to search for buoy i * With buoy i1 * and buoy i2 * The corresponding acoustic buoy is i ** .

[0141] r(i * ,i ** )=min{r(i * ,i1 * ),r(i * ,i2 * )} (6)

[0142] Where: r(i * ,i1 * ) is the buoy i * With buoy i1 * The spacing, r(i * ,i2 * ) is the buoy i * With buoy i2 * spacing.

[0143] The acoustic buoy warning unit is (i * ,i ** ).

[0144] The following is an introduction to the process of constructing the cross-air-sea medium attenuation prediction model in this embodiment:

[0145] In this embodiment, see Figure 5 , the method of joint positioning of acoustic buoy warning unit in step 2 is introduced:

[0146] In the plane coordinate system Oxy, the warning buoy unit (i * ,i ** ) Get measurement information z ki (i=i * ,i ** ), using joint positioning technology to obtain measurements containing position information (x k(i*)j ,y k(i*)j ,e k(i*)j ), and eliminate background noise and interference outside the joint positioning area to achieve measurement information expansion.

[0147] In this embodiment, see Figure 6 , the TBD theory and Hough transform algorithm in step three specifically include:

[0148] Step 1: Use TBD theory to select the information fragment to be processed. In chronological order, randomly select the measurement information within K (5≤K≤7) consecutive moments to obtain the measurement point set Z to be detected. k In the coordinate system Oxy, the set of measurement points at time k is

[0149] Z k ={(x i*k ,y i*k ,e i*k )}(k=1,…,K) (7)

[0150] Step 2: Construct data space A = {Z1,…,Z K}, parameter space B, accumulation matrix D and energy accumulation matrix E, and initialize B, D and E.

[0151] Step 3: Perform random Hough transform detection on A and B, and eliminate most of the background noise and interference to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track. The double threshold accumulation formula of the number of points and energy is:

[0152]

[0153] Where: (θ t ,ρ m ) represents the coordinates of the center points of each parameter unit in B, and “+=” represents the accumulation operation;

[0154] If the initial point does not exist, repeat steps 1 to 3.

[0155] In this embodiment, see Figure 7 , the method of point trace constraint processing in step 4 specifically includes:

[0156] If the detected point trace in step 3 exists, point trace constraint processing is performed, and data points at any adjacent k, k+1, and k+2 moments in the initial point trace are selected, and motion elements such as velocity, acceleration, heading angle, and heading angle change rate are calculated to constrain the initial point trace.

[0157] Step 1: Speed ​​constraint processing. In the coordinate system Oxy, the speed constraint condition is

[0158]

[0159] Where: v xmax is the maximum velocity in the x direction, v ymax is the maximum velocity in the y direction, v k is the speed value in the predicted value of energy change.

[0160] Step 2: Acceleration constraint processing. The acceleration constraint condition is

[0161]

[0162] Step 3: Heading angle constraint processing. The heading angle constraint condition is

[0163]

[0164] Step 4: Heading angle change rate constraint processing. The heading angle change rate constraint condition is:

[0165]

[0166] According to the prior information such as the predicted value of the energy transmission change, the initial point traces that meet the constraints are merged, the initial point traces that do not meet the constraints are eliminated, the noise and interference point traces are eliminated, and the target point traces with high fitting degree are obtained. That is, the detection of supersonic targets near the water surface is completed.

[0167] Compared with the prior art, the method for detecting supersonic targets near the water surface based on an acoustic buoy array described in the present invention has the following beneficial effects:

[0168] (1) The present invention utilizes the prediction of acoustic energy attenuation across air-sea media to achieve the matching of the underwater propagation signal of the radiation noise of the supersonic target near the water surface.

[0169] (2) The present invention utilizes the construction of an acoustic buoy warning unit to achieve joint positioning, expand measurement information, and eliminate background noise and interference outside the joint positioning area to obtain information to be processed.

[0170] (3) The present invention utilizes the technical advantages of existing TBD and Hough transform technologies in the field of weak target detection to achieve the detection of supersonic targets near the water surface that are moving in an approximately linear manner.

[0171] Example 2

[0172] This embodiment provides a near-surface supersonic target detection system based on an acoustic buoy array, see Figure 8 , the system comprising:

[0173] The cross-air-sea medium acoustic energy attenuation prediction module T1 uses the radiation noise of the near-surface supersonic target and the characteristics of the air-sea medium to build a cross-air-sea medium attenuation prediction model to achieve the matching of the radiation noise of the near-surface supersonic target with the underwater propagation signal; the movement speed of the near-surface supersonic target does not exceed Mach 4;

[0174] The acoustic buoy warning unit processing module T2 determines the formation, buoy spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship and the meteorological and hydrological conditions. After the acoustic buoy receives the hydroacoustic signal, it transmits it back to the underwater acoustic signal processing system via radio equipment. The maximum energy and minimum spacing method is used to automatically select the acoustic buoy warning unit, and the warning buoy unit is used to jointly locate the hydroacoustic signal, and the background noise and interference outside the joint positioning area are eliminated to obtain the information to be processed. The acoustic buoy is a passive buoy sonar with direction finding function.

[0175] TBD and Hough transform processing module T3, using TBD to select the information fragment to be processed, perform Hough transform processing on the information fragment to be processed, and eliminate most of the background noise and interference, to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track;

[0176] The point track constraint processing module T4 calculates the motion elements such as velocity, acceleration, heading angle and heading angle change rate to constrain the initial point track, eliminate noise and interference point tracks, and obtain the true track of the target, thus completing the detection of supersonic targets near the water surface.

[0177] In this embodiment, the cross-air-sea medium acoustic energy attenuation prediction module T1 specifically includes:

[0178] The cross-air-sea medium sound energy attenuation prediction unit considers factors such as sound velocity, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, underwater sound propagation refractive index, Doppler frequency shift, etc. to build a cross-air-sea medium sound energy attenuation prediction model;

[0179] Assume that the supersonic target near the water surface moves approximately in a straight line. The sound energy of the supersonic target radiation noise will attenuate during the propagation process across the air-sea medium. The predicted value of the sound energy attenuation of the supersonic target radiation noise near the water surface after entering the water from the air at time k is

[0180] e as(k) =F(v (k) ,p r(k) ,t h(k),r e(k) ,Δf (k) ,r d(k) ,l vh(k) )

[0181] Where v is the speed of sound, r d is the attenuation rate, l vh is the viscosity and heat loss, p r is the Prandtl number, t h is the boundary layer thickness, r e is the refractive index of underwater sound propagation, and Δf is the Doppler frequency shift.

[0182] In this embodiment, the acoustic buoy warning unit processing module T2 specifically includes:

[0183] The acoustic buoy warning array deployment unit determines the formation, buoy spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship, as well as the meteorological and hydrological conditions; the acoustic buoy is a passive buoy sonar with direction-finding function.

[0184] Assume that the acoustic buoy warning array consists of N passive direction-finding sonar buoys with adjacent spacing d. In the coordinate system Oxy, the buoy position coordinates are (x si ,y si )(i=1,2,…,N), the measurement data set of the ith acoustic buoy at time k is Z i ={z ki |k=1,2,…,K}. The data set received by the ith acoustic buoy at time k is

[0185] z ki ={(α k(i)j ,e k(i)j )|j=1,2,…,n j}

[0186] Among them, n j is the number of measurements, α k(i)j is the azimuth of the jth measurement, e k(i)j is the energy of the jth measurement.

[0187] Optionally, the energy set measured by the i-th acoustic buoy at time k is

[0188] {e k(i)j |i=1,2,…,N,j=1,2,…,n j}

[0189] Optionally, the energy of the jth measurement of the ith acoustic buoy at time k is

[0190] e k(i)j ∈{e as(kij) ,eno(kij) ,e jim(kij)}(i=1,2,…,N,j=1,2,…,n j )

[0191] Among them, e as(kij) is the target energy value, e no(kij) is the energy value of the background noise, e jim(kij) is the energy value of the interference.

[0192] The acoustic-to-electric conversion and signal feedback unit receives the underwater acoustic signal and transmits it back to the underwater acoustic signal processing system via radio equipment.

[0193] The acoustic buoy alarm selection unit uses the maximum energy and minimum spacing method to automatically select the acoustic buoy alarm unit.

[0194] Optionally, the maximum value method is used to search for the maximum energy value, and the corresponding acoustic buoy is i * .

[0195]

[0196] Among them, the decision threshold is N s / 2,N s is the number of buoys in the acoustic buoy warning array, and N is the buoy accumulation matrix.

[0197] According to the maximum energy value formula, we further search the acoustic buoy warning array and obtain two buoys with the next maximum energy value i1 * and i2 * .

[0198] Optionally, use the minimum spacing method to search for buoy i * With buoy i1 * and buoy i2 * The corresponding acoustic buoy is i ** .

[0199] r(i * ,i ** )=min{r(i * ,i1 * ),r(i * ,i2 * )}

[0200] Among them, r(i * ,i1 * ) is the buoy i * With buoy i1 * The spacing, r(i * ,i2 * ) is the buoy i * With buoy i2 * spacing.

[0201] The acoustic buoy warning unit is (i * ,i ** ).

[0202] The joint positioning hydroacoustic signal unit uses the alarm buoy unit to jointly position the hydroacoustic signal, and eliminates background noise and interference outside the joint positioning area to obtain the information to be processed.

[0203] In the plane coordinate system Oxy, the warning buoy unit (i * ,i ** ) Get measurement information z ki (i=i * ,i ** ), using joint positioning technology to obtain measurements containing position information (x k(i*)j ,y k(i*)j ,e k(i*)j ), and eliminate background noise and interference outside the joint positioning area to achieve measurement information expansion.

[0204] In this embodiment, the TBD and Hough transform processing module T3 specifically includes:

[0205] The TBD and Hough transform processing module uses the TBD theory to select the information fragments to be processed, performs Hough transform processing on the information fragments to be processed, and eliminates most of the background noise and interference to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track;

[0206] TBD selects the information fragment unit to be processed. The information fragment to be processed is selected using TBD theory. According to the time sequence, the measurement information within K (5≤K≤7) consecutive moments is randomly selected to obtain the measurement point set Z to be detected. k In the coordinate system Oxy, the set of measurement points at time k is

[0207] Z k ={(x i*k ,y i*k ,e i*k )}(k=1,…,K).

[0208] The Hough transform processing unit performs Hough transform processing on the information fragment to be processed and eliminates most of the background noise and interference to obtain an initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track.

[0209] Construct data space A={Z1,…,Z K}, parameter space B, accumulation matrix D and energy accumulation matrix E, and initialize B, D and E.

[0210] A and B are detected by random Hough transform, and most of the background noise and interference are eliminated to obtain the initial point track set of target, noise and interference that meets the requirement of approximate linear motion of the track.

[0211] Optionally, the dual threshold accumulation formula for points and energy is

[0212]

[0213] Among them, (θ t ,ρ m ) represents the center point coordinates of each parameter unit in B, and “+=” is an accumulation operation.

[0214] If the initial point trace does not exist, repeat steps

[00205] -

[00210] .

[0215] In this embodiment, the point trace constraint processing module T4 specifically includes:

[0216] The point trace constraint processing module performs point trace constraint processing if the point trace detected in the TBD and Hough transform processing modules exists. It selects data points at any adjacent k, k+1, and k+2 moments in the initial point trace, calculates motion elements such as velocity, acceleration, heading angle, and heading angle change rate, and performs constraint processing on the initial point trace.

[0217] Speed ​​constraint processing unit, in the coordinate system Oxy, the speed constraint condition is

[0218]

[0219] Among them, v xmax is the maximum velocity in the x direction, v ymax is the maximum velocity in the y direction, v k is the speed value in the predicted value of energy change.

[0220] Acceleration constraint processing unit, the acceleration constraint condition is

[0221]

[0222] Heading angle constraint processing unit, the heading angle constraint condition is

[0223]

[0224] Heading angle change rate constraint processing unit, the heading angle change rate constraint condition is

[0225]

[0226] According to the prior information such as the predicted value of energy change, the initial traces that meet the constraints are merged, the initial traces that do not meet the constraints are eliminated, the noise and interference traces are eliminated, and the target traces with high fitting degree are obtained. That is, the detection of supersonic targets near the water surface is completed.

[0227] As for the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0228] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for detecting supersonic targets near the water surface based on an acoustic buoy array, characterized in that: include: Step 1: Construct a cross-air-sea medium attenuation prediction model to achieve the matching of the underwater propagation signal of the radiation noise of the supersonic target near the water surface; The speed of a supersonic target approaching the water surface shall not exceed Mach 4; Step 2: Automatically select the acoustic buoy warning unit using the maximum energy and minimum spacing method, use the warning buoy unit joint positioning technology to expand the measurement information, and eliminate the background noise and interference outside the joint positioning area to obtain the information to be processed; the acoustic buoy is a passive buoy sonar with direction finding function; Step 3: Use TBD theory to select the information fragments to be processed, perform Hough transform on the information fragments to be processed, and eliminate most of the background noise and interference to obtain the initial point track set of the target, noise and interference that meets the approximate linear motion of the track; Step 4: Set the motion elements such as velocity, acceleration, heading angle and heading angle change rate to constrain the initial point track set, eliminate noise and interference points, and obtain the true track of the target, thus completing the detection of supersonic targets near the water surface.

2. The method for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 1, characterized in that: Step 1 specifically includes: Assuming that the supersonic target near the water surface moves approximately in a straight line, the radiated noise of the supersonic target will attenuate in the process of propagation across the air-sea medium. Considering the influence of factors such as sound speed, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, refractive index of underwater sound propagation, and Doppler frequency shift, a prediction model for acoustic energy attenuation across the air-sea medium is constructed to predict the energy change of the radiated noise of the supersonic target near the water surface when it enters the water from the air.

3. The method for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 1, characterized in that: Step 2 specifically includes: Assume that the acoustic buoy warning array consists of N passive direction-finding sonar buoys with adjacent spacing d. The acoustic buoy receives a set of energy values ​​at time k. The maximum energy value formula is used to search for the buoy i with the maximum energy value in the acoustic warning array. * And the next maximum energy value of two buoys i1 * and i2 * , calculate the buoy i * With buoy i1 * and buoy i2 * The spacing r(i * ,i1 * )、r(i * ,i2 * ), and then search for the corresponding acoustic buoy i according to the minimum spacing formula ** In the plane coordinate system Oxy, using the warning buoy unit (i * ,i ** ) Get measurement information z ki (i=i * ,i ** ), using joint positioning technology to obtain measurements containing position information And eliminate background noise and interference outside the joint positioning area to achieve measurement information expansion.

4. The method for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 1, characterized in that: Step three specifically includes: Use TBD theory to select the information fragments to be processed. According to the time sequence, randomly select the measurement information within K (5≤K≤7) consecutive moments to obtain the measurement point set Z to be detected. k ; Construct data space A={Z1,…,Z K }, parameter space B, accumulation matrix D and energy accumulation matrix E, and initialize B, D and E; perform random Hough change detection on A and B, and eliminate most of the background noise and interference to obtain the initial point track set of target, noise and interference that meets the approximate straight-line motion of the track.

5. The method for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 1, characterized in that: Step 4 specifically includes: If the detected point trace in step 3 exists, point trace constraint processing is performed, and data points at any adjacent k, k+1, and k+2 moments in the initial point trace are selected, and motion elements such as velocity, acceleration, heading angle, and heading angle change rate are calculated to constrain the initial point trace.

6. A near-surface supersonic target detection system based on an acoustic buoy array, characterized in that: include: The cross-air-sea medium acoustic energy attenuation prediction module uses the radiation noise of supersonic targets near the water surface and the characteristics of air-sea media to build a cross-air-sea medium attenuation prediction model to achieve the matching of the radiation noise of supersonic targets near the water surface with the underwater propagation signal; The speed of a supersonic target approaching the water surface shall not exceed Mach 4; The processing module of the acoustic buoy warning unit determines the formation, spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship and the meteorological and hydrological conditions. After the acoustic buoy receives the hydroacoustic signal, it transmits it back to the underwater acoustic signal processing system via the radio equipment. The maximum energy and minimum spacing method is used to automatically select the acoustic buoy warning unit, and the warning buoy unit is used to jointly locate the hydroacoustic signal, and the background noise and interference outside the joint positioning area are eliminated to obtain the information to be processed. The acoustic buoy is a passive buoy sonar with a direction-finding function. The TBD sampling and Hough transform processing module uses the TBD theory to select the information fragments to be processed, performs Hough transform processing on the information fragments to be processed, and eliminates most of the background noise and interference to obtain the initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track; The point track constraint processing module sets motion elements such as velocity, acceleration, heading angle and heading angle change rate to constrain the initial point track, eliminate noise and interference point tracks, and obtain the true track of the target, thereby completing the detection of supersonic targets near the water surface.

7. The system for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 6, characterized in that: The cross-air-sea medium acoustic energy attenuation prediction module specifically includes: The cross-air-sea medium acoustic energy attenuation prediction unit assumes that the supersonic target near the water surface moves approximately in a straight line, and the supersonic target radiation noise has acoustic energy attenuation during the propagation process across the air-sea medium; considering the influence of factors such as sound speed, attenuation rate, viscosity and heat loss, Prandtl number, boundary layer thickness, underwater sound propagation refractive index, Doppler frequency shift, etc., a cross-air-sea medium acoustic energy attenuation prediction model is constructed to realize the prediction of the energy change of the radiation noise of the supersonic target near the water surface when it enters the water from the air.

8. The system for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 6, characterized in that: The acoustic buoy warning unit processing module specifically includes: The acoustic buoy warning array deployment unit determines the formation, buoy spacing and number of the acoustic buoy warning array according to the distance between the nearby surface supersonic target and the surface ship and the meteorological and hydrological conditions; the acoustic buoy is a passive buoy sonar with direction finding function; The acoustic-to-electric conversion and signal feedback unit, after the acoustic buoy receives the underwater acoustic signal, transmits it back to the underwater acoustic signal processing system via the radio equipment; the acoustic buoy alarm selection unit, which automatically selects the acoustic buoy alarm unit using the maximum energy and minimum spacing method; The joint positioning hydroacoustic signal unit uses the alarm buoy unit to jointly position the hydroacoustic signal, and eliminates background noise and interference outside the joint positioning area to obtain the information to be processed.

9. The system for detecting supersonic targets near the water surface based on an acoustic buoy array according to claim 6, characterized in that: The TBD and Hough transform processing module specifically includes: TBD selects the information fragment unit to be processed, and uses TBD theory to randomly select the measurement information within K (5≤K≤7) consecutive moments in time sequence to obtain the measurement point set Z to be detected. k ; The Hough transform processing unit performs Hough transform processing on the information fragment to be processed and eliminates most of the background noise and interference to obtain an initial point track set of the target, noise and interference that satisfies the approximate linear motion of the track.

10. The near-surface supersonic target detection system based on an acoustic buoy array according to claim 6, characterized in that: The point trace constraint processing module specifically includes: If the detection point trace exists in the TBD and Hough transform processing modules, point trace constraint processing is performed, and data points at any adjacent k, k+1, and k+2 moments in the initial point trace are selected, and motion elements such as velocity, acceleration, heading angle, and heading angle change rate are calculated to constrain the initial point trace; Speed ​​constraint processing unit; acceleration constraint processing unit; heading angle constraint processing unit; heading angle change rate constraint processing unit; According to the prior information such as the predicted value of the energy transmission change, the initial point traces that meet the constraints are merged, and the initial point traces that do not meet the constraints are eliminated, the noise and interference point traces are eliminated, and the target point traces with high fitting degree are obtained, thus completing the detection of supersonic targets near the water surface.

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