Bistatic ISAR imaging segmental arc selection method for aerial moving target

Abstract

The invention provides a bistatic ISAR imaging arc section selection method for an air moving target, and relates to the technical field of bistatic radar imaging, and the method comprises the steps: obtaining the position information of a transmitting station, a receiving station and the air moving target, and converting the position information of the transmitting station, the receiving station and the air moving target into the coordinates of an earth-centered earth-fixed coordinate system; establishing a translation simulation model, a rotation simulation model and an echo model of the air moving target; the method comprises the following steps: determining a first constraint condition and a second constraint condition of a double-base-angle change rate of an air moving target according to a translation simulation model, a rotation simulation model and an echo model of the air moving target; selecting a target imaging arc section according to the earth-centered earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the air moving target; therefore, the high-resolution imaging of the air moving target can be quickly and accurately obtained according to the target imaging arc segment, and the processing efficiency and the image quality can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bistatic radar imaging, and in particular to a bistatic ISAR imaging arc selection method for aerial moving targets. Background Art

[0002] Bistatic Inverse Synthetic Aperture Radar (Bi-ISAR) is a radar that is deployed in a space with separate transmitters and receivers. It fully utilizes the spatial diversity advantages of the transmitting and receiving stations to achieve high-resolution two-dimensional imaging of targets with arbitrary flight trajectories.

[0003] The imaging quality of Bi-ISAR is determined, on the one hand, by the observation configuration and imaging arc, ensuring that the data segments within the imaging arc have the potential for two-dimensional high-resolution imaging; on the other hand, it is determined by the bistatic ISAR imaging algorithm, which, through parameter estimation and motion compensation technology, ensures that the data segments within the imaging arc can obtain clearer images than traditional methods.

[0004] Among related technologies, research on Bi-ISAR imaging mainly focuses on imaging algorithms and motion compensation, which is mainly based on the basic assumption that the data within the imaging arc "meets the imaging conditions". It has problems such as low processing efficiency and poor imaging quality. Summary of the Invention

[0005] The present invention provides a bistatic ISAR imaging arc segment selection method for aerial moving targets. The method can determine the bistatic ISAR imaging process of the aerial moving target by constructing a bistatic ISAR imaging echo model and a maneuvering model of the aerial moving target. Finally, a first constraint condition of a distance constraint and a second constraint condition of an azimuth constraint are obtained by boundary deduction of a bistatic angle change rate. The method then implements the selection of the target imaging arc segment of the bistatic ISAR imaging under resolution constraint through the first constraint condition and the second constraint condition, thereby effectively improving processing efficiency and imaging quality.

[0006] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0007] In a first aspect, a method for selecting a bistatic ISAR imaging arc for an airborne moving target is provided, the method comprising: obtaining position information of a transmitting station, a receiving station, and the airborne moving target, the position information including longitude, latitude, and altitude; converting the position information of the transmitting station, the receiving station, and the airborne moving target into a geocentric, earth-fixed coordinate system; establishing a translational simulation model, a rotational simulation model, and an echo model of the airborne moving target; determining a first constraint and a second constraint of a bistatic angle change rate of the airborne moving target based on the translational simulation model, the rotational simulation model, and the echo model of the airborne moving target, wherein the first constraint is a distance constraint and the second constraint is an azimuth constraint; based on the first constraint and the second constraint, selecting a target imaging arc according to the geocentric, earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the airborne moving target;

[0008] The first constraint condition for the rate of change of the double base angle is:

[0009]

[0010] Where c is the speed of light, β(t0) is the instantaneous bi-basic angle at time t0, B is the bandwidth of the transmitted signal, and y p is the initial ordinate of the scattering point on the target relative to the scattering center, T s accumulating time for coherence;

[0011] The second constraint on the rate of change of the dual base angles is:

[0012]

[0013] Among them, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

[0014] In a possible implementation of the first aspect, a formula for converting the location information of the transmitting station into coordinates of an Earth-centered Earth-fixed coordinate system is:

[0015]

[0016] The formula for converting the position information of the receiving station into the Earth-centered Earth-fixed coordinate system is:

[0017]

[0018] The formula for converting the position information of an aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0019]

[0020] Among them, the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,LT ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major semi-axis of the Earth's ellipsoid, a = 6378137 meters.

[0021] In a possible implementation of the first aspect, the translation simulation model is:

[0022]

[0023] Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m =mPRT (m=0,1,2,…) is the azimuth slow time;

[0024] The rotation simulation model is:

[0025] K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ;

[0026]

[0027] Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time;

[0028] The echo model is:

[0029]

[0030] Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, Tp is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

[0031] In a possible implementation of the first aspect, based on the first constraint and the second constraint, selecting a target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target includes:

[0032] Determining a dual base angle conversion rate threshold based on a first constraint and a second constraint;

[0033] Determine the dual-base angle transformation rate corresponding to each imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the aerial moving target;

[0034] An imaging arc segment whose dual-base angle transformation rate is less than a dual-base angle transformation rate threshold is determined as a target imaging arc segment;

[0035] Among them, the dual base angle conversion rate threshold The formula for determining is:

[0036]

[0037] In a possible implementation of the first aspect, after selecting the target imaging arc according to the geocentric Earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the airborne moving target based on the first constraint and the second constraint, the above method also includes: setting the beam pointing areas of the transmitting station and the receiving station to the same spatial position; setting the carrier center frequencies of the transmitting station and the receiving station to the target frequency; and sending instructions to the transmitting station and the receiving station, the instructions being used to instruct the transmitting station and the receiving station to determine high-resolution imaging of the airborne moving target based on the target imaging arc.

[0038] The beneficial effects of the present invention are as follows: the method provided by the present invention can determine the bistatic ISAR imaging process of an aerial moving target by constructing a bistatic ISAR imaging echo model and a maneuvering model of bistatic ISAR imaging, and finally obtain the first constraint condition of the distance constraint and the second constraint condition of the azimuth constraint by deducing the boundary of the bistatic angle change rate, and then realize the selection of the target imaging arc segment of bistatic ISAR imaging under resolution constraint by the first constraint condition and the second constraint condition, thereby effectively improving the processing efficiency and imaging quality. In other words, the method provided by the present invention can quickly and quantitatively calculate the bistatic angle and bistatic angle change rate boundary conditions under different observation configurations through the resolution constraint condition, quickly screen out the selected target imaging arc segment, and optimize the imaging performance of the entire system. In addition, the method provided by the present invention does not require hardware improvements to existing radar equipment, has good flexibility and adaptability, and can meet the use requirements of different usage scenarios.

[0039] In a second aspect, the present invention provides a bistatic ISAR imaging arc selection system for airborne moving targets, the system comprising: an information acquisition module for acquiring position information of a transmitting station, a receiving station and an airborne moving target, the position information comprising longitude, latitude and altitude; a coordinate conversion module for converting the position information of the transmitting station, the receiving station and the airborne moving target into geocentric earth-fixed coordinate system coordinates; a model establishment module for establishing a translational simulation model, a rotational simulation model and an echo model of the airborne moving target; a constraint determination module for determining a first constraint and a second constraint of a bistatic angle change rate of the airborne moving target based on the translational simulation model, the rotational simulation model and the echo model of the airborne moving target, wherein the first constraint is a distance constraint and the second constraint is an azimuth constraint; an arc selection module for selecting a target imaging arc based on the geocentric earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the airborne moving target based on the first constraint and the second constraint;

[0040] The first constraint condition for the rate of change of the double base angle is:

[0041]

[0042] Where c is the speed of light, β(t0) is the instantaneous double base angle at time t0, B is the bandwidth of the transmitted signal, and y p is the initial ordinate of the scattering point on the target relative to the scattering center, T s accumulating time for coherence;

[0043] The second constraint on the rate of change of the dual base angles is:

[0044]

[0045] Among them, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

[0046] In a possible implementation of the second aspect, the formula for converting the location information of the transmitting station into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0047]

[0048] The formula for converting the position information of the receiving station into the Earth-centered Earth-fixed coordinate system is:

[0049]

[0050] The formula for converting the position information of an aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0051]

[0052] Among them, the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,L T ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major semi-axis of the Earth's ellipsoid, a = 6378137 meters.

[0053] The translation simulation model is:

[0054]

[0055] Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m =mPRT (m=0,1,2,…) is the azimuth slow time;

[0056] The rotation simulation model is:

[0057] K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ;

[0058]

[0059]

[0060] Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time;

[0061] The echo model is:

[0062]

[0063] Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, T p is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

[0064] In a possible implementation of the second aspect, the arc segment selection module is specifically configured to: determine a dual-base angle transformation rate threshold based on the first constraint and the second constraint; determine a dual-base angle transformation rate corresponding to each imaging arc segment based on the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target; and determine an imaging arc segment having a dual-base angle transformation rate less than the dual-base angle transformation rate threshold as a target imaging arc segment;

[0065] Among them, the dual base angle conversion rate threshold The formula for determining is:

[0066]

[0067] In a possible implementation of the second aspect, after the arc selection module selects the target imaging arc according to the geocentric coordinate system coordinates of the transmitting station, the receiving station and the airborne moving target based on the first constraint condition and the second constraint condition, the above-mentioned system also includes a space-time-frequency synchronization module and a high-resolution imaging module; the space-time-frequency synchronization module is used to set the beam pointing area of ​​the transmitting station and the receiving station to the same spatial position; and is used to set the carrier center frequency of the transmitting station and the receiving station to the target frequency; the high-resolution imaging module is used to send instructions to the transmitting station and the receiving station, and the instructions are used to instruct the transmitting station and the receiving station to determine the high-resolution imaging of the airborne moving target according to the target imaging arc.

[0068] In a third aspect, an electronic device is provided, comprising a memory and one or more processors; the memory is coupled to the processor; wherein computer program code is stored in the memory, and the computer program code comprises computer instructions, and when the computer instructions are executed by the processor, the electronic device executes a method as in any implementation of the first aspect.

[0069] In a fourth aspect, a computer-readable storage medium is provided, comprising computer instructions. When the computer instructions are executed on an electronic device, the electronic device executes the method in any implementation of the first aspect.

[0070] According to a fifth aspect, a computer program product is provided. When the computer program product is run on a computer, the computer is caused to execute the method in any implementation of the first aspect.

[0071] It can be understood that the beneficial effects that can be achieved by the system of the second aspect, the electronic device of the third aspect, the computer-readable storage medium of the fourth aspect, and the computer program product of the fifth aspect provided above can be referred to the beneficial effects in the first aspect and any possible design method thereof, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 A schematic diagram of an application scenario provided by an embodiment of the present invention;

[0073] Figure 2 A schematic structural diagram of an electronic device provided by an embodiment of the present invention;

[0074] Figure 3 A flowchart of a method for selecting arc segments in bistatic ISAR imaging for aerial moving targets provided by an embodiment of the present invention;

[0075] Figure 4 A flowchart of another method for selecting arc segments in bistatic ISAR imaging for aerial moving targets provided by an embodiment of the present invention;

[0076] Figure 5 Another method for selecting bistatic ISAR imaging arc segments for aerial moving targets is shown in an embodiment of the present invention;

[0077] Figure 6 A schematic diagram of a dual-base test simulation scenario provided by an embodiment of the present invention;

[0078] Figure 7 A schematic diagram of a dot matrix target for bistatic ISAR imaging provided by an embodiment of the present invention;

[0079] Figure 8 A dual-base angle change rate constraint curve in the distance dimension provided by an embodiment of the present invention;

[0080] Figure 9 A dual-base angle change rate constraint curve in an azimuth dimension provided by an embodiment of the present invention;

[0081] Figure 10 The embodiment of the present invention provides a dual-base angle change rate in an imaging arc segment in a scenario where the target speed is 50 m / s;

[0082] Figure 11 The embodiment of the present invention provides a dual-base angle change rate in an imaging arc segment in a scenario where the target speed is 120 m / s;

[0083] Figure 12 The embodiment of the present invention provides a dual-base angle change rate in an imaging arc segment in a scenario where the target speed is 200 m / s;

[0084] Figure 13 The embodiment of the present invention provides a two-dimensional point expansion result of an edge point target under the condition that the target speed is 50m / s;

[0085] Figure 14 The embodiment of the present invention provides a two-dimensional point expansion result of an edge point target under the condition that the target speed is 120m / s;

[0086] Figure 15 The embodiment of the present invention provides a two-dimensional point expansion result of an edge point target with a target speed of 200m / s;

[0087] Figure 16 A schematic diagram of the structure of a selection system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0088] Bistatic Inverse Synthetic Aperture Radar (Bi-ISAR) is a radar that is deployed in a space with separate transmitters and receivers. It fully utilizes the spatial diversity advantages of the transmitting and receiving stations to achieve high-resolution two-dimensional imaging of targets with arbitrary flight trajectories.

[0089] The imaging quality of Bi-ISAR is determined, on the one hand, by the observation configuration and imaging arc, ensuring that the data segments within the imaging arc have the potential for two-dimensional high-resolution imaging; on the other hand, it is determined by the bistatic ISAR imaging algorithm, which, through parameter estimation and motion compensation technology, ensures that the data segments within the imaging arc can obtain clearer images than traditional methods.

[0090] Among related technologies, research on Bi-ISAR imaging mainly focuses on imaging algorithms and motion compensation, which is mainly based on the basic assumption that the data within the imaging arc "meets the imaging conditions". It has problems such as low processing efficiency and poor imaging quality.

[0091] In view of this, an embodiment of the present invention provides a method for selecting bistatic ISAR imaging arcs for airborne moving targets, the method comprising: obtaining position information of a transmitting station, a receiving station, and the airborne moving target, the position information including longitude, latitude, and altitude; converting the position information of the transmitting station, the receiving station, and the airborne moving target into coordinates of an Earth-centered Earth-fixed coordinate system; establishing a translational simulation model, a rotational simulation model, and an echo model of the airborne moving target; determining a first constraint and a second constraint of a bistatic angle change rate of the airborne moving target based on the translational simulation model, the rotational simulation model, and the echo model of the airborne moving target, wherein the first constraint is a distance constraint and the second constraint is an azimuth constraint; based on the first constraint and the second constraint, selecting a target imaging arc according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the airborne moving target;

[0092] The method provided by the present invention can determine the bistatic ISAR imaging process of an aerial moving target by constructing a bistatic ISAR imaging echo model and a maneuvering model of bistatic ISAR imaging. Finally, by deducing the boundary of the bistatic angle change rate, a first constraint condition of the distance constraint and a second constraint condition of the azimuth constraint are obtained. Then, the first constraint condition and the second constraint condition are used to select the target imaging arc segment of bistatic ISAR imaging under resolution constraint, thereby effectively improving processing efficiency and imaging quality. In other words, the method provided by the present invention can quickly and quantitatively calculate the bistatic angles and the bistatic angle change rate boundary conditions under different observation configurations through the resolution constraint condition, quickly screen out the selected target imaging arc segment, and optimize the imaging performance of the entire system. In addition, the method provided by the present invention does not require hardware improvements to existing radar equipment, has good flexibility and adaptability, and can meet the use requirements of different usage scenarios.

[0093] See also Figure 1 , Figure 1 A schematic diagram of an application scenario proposed by an embodiment of the present invention includes a transmitting station 10, a receiving station 20, and an aerial moving target 30. The transmitting station 10 and the receiving station 20 are used to determine a high-resolution image of the aerial moving target 30.

[0094] In some embodiments, a bistatic ISAR imaging arc segment selection method for aerial moving targets provided by an embodiment of the present invention can be executed by a bistatic ISAR imaging arc segment selection system 100 for aerial moving targets (hereinafter referred to as the selection system 100), and the selection system 100 communicates with the transmitting station 10 and the receiving station 20 respectively.

[0095] As an example, the selection system 100 can be any electronic device 200 with data processing capabilities, such as a general-purpose computer, a personal computer, a laptop computer, a switch or a tablet computer, etc. The specific implementation method of the selection system 100 is not limited here.

[0096] Figure 2 The electronic device 200 includes a processor 210 , a memory 220 , and a communication interface 230 .

[0097] The processor 210 may include one or more processing cores. The processor 210 uses various interfaces and lines to connect various parts of the electronic device 200, and executes various functions of the electronic device 200 and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 220, and calling data stored in the memory 220. Optionally, the processor 210 can be implemented in the form of at least one hardware of a central processing unit (CPU), a graphics processing unit (GPU), a digital signal processing (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA).

[0098] The memory 220 may include a random access memory (RAl) or a read-only memory (ROL). Optionally, the memory 220 includes a non-transitory computer-readable storage medium (NMT). The memory 220 may be used to store instructions, programs, codes, code sets, or instruction sets. The memory 220 may include a program storage area. The program storage area may store instructions for implementing an operating system, instructions for implementing at least one function (such as a video acquisition function, a feature extraction function, and a process detection function), instructions for implementing the above-mentioned various method embodiments, etc.

[0099] The communication interface 230 is used to communicate with other devices, equipment or communication networks, such as data storage devices, image processing equipment or Ethernet, radio access network (RAN), wireless local area network (WLAN), etc.

[0100] In physical implementation, the aforementioned components (e.g., processor 210, memory 220, and communication interface 230) may be components within the same device (e.g., a laptop). Alternatively, at least two of the components may be provided within the same device, i.e., as different components within a single device, similar to the deployment of devices or components in a distributed system.

[0101] It should be understood that the structure illustrated in this embodiment does not constitute a specific limitation on the electronic device 200. In other embodiments of the present invention, the electronic device 200 may include more or fewer components than shown, or may combine or separate certain components, or arrange the components differently. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0102] A bistatic ISAR imaging arc segment selection method for aerial moving targets provided by an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0103] Figure 3 Flowchart of a method for selecting arc segments for bistatic ISAR imaging of aerial moving targets provided by an embodiment of the present invention. Optionally, the method can be executed by the electronic device 200 shown in FIG. 2 , that is, by the selection system 100. The method can include the following steps:

[0104] S1. Obtain the location information of the transmitting station, receiving station and aerial moving target, including longitude, latitude and altitude;

[0105] S2, converting the position information of the transmitting station, the receiving station and the aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system;

[0106] Specifically, the Earth-centered, Earth-fixed (ECEF) coordinate system is a fixed coordinate system with the Earth's center of mass as its origin and which rotates with the Earth. It is widely used in aerospace, navigation, radar imaging and other fields.

[0107] In one possible implementation, the formula for converting the location information of the transmitting station into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0108]

[0109] The formula for converting the position information of the receiving station into the Earth-centered Earth-fixed coordinate system is:

[0110]

[0111]

[0112] The formula for converting the position information of an aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0113]

[0114] Among them, N T N is the curvature radius of the transmitting station's unitary plane, R N is the curvature radius of the receiving station's azimuth plane, Ois the curvature radius of the unitary plane of the aerial moving target, and the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,L T ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major semi-axis of the Earth's ellipsoid, a = 6378137 meters.

[0115] As can be seen from the above, the method provided by the embodiment of the present invention converts coordinates into geocentric, earth-fixed coordinate system coordinates. When the transmitting station, receiving station, and aerial moving target are located in different geographical locations, the geocentric, earth-fixed coordinate system can provide a globally unified coordinate description, avoiding the conversion complexity of local coordinate systems. In addition, the relative position and velocity of the transceiver station and the aerial moving target can be quickly and accurately determined, facilitating the determination of dual base angles and slant ranges. Finally, for long-range aerial moving targets (such as satellites and high-altitude aircraft), the influence of the earth's curvature on the final result can be considered, and the geocentric, earth-fixed coordinate system can support spherical geometry calculations.

[0116] S3. Establishing a translation simulation model, a rotation simulation model and an echo model of an aerial moving target;

[0117] In some embodiments, the translation simulation model is:

[0118]

[0119] Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m =mPRT (m=0,1,2,…) is the azimuth slow time.

[0120] The rotation simulation model is:

[0121] K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m2 ;

[0122]

[0123] Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time;

[0124] The echo model is:

[0125]

[0126] Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, T p is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

[0127] The following is an example to explain the process of establishing the echo model, the translation simulation model and the rotation simulation model of the present invention.

[0128] In one example, when the transmitting station radar transmits a linear frequency modulation signal, the specific expression is as follows:

[0129]

[0130] Where τ is the distance time, f c is the carrier frequency of the radar signal, T p is the pulse width; μ is the modulation frequency of the signal.

[0131] The transmitted electromagnetic wave propagates through the dual-base configuration, and the received echo signal can be described as

[0132]

[0133] Where σ is the scattering coefficient of the target, c is the speed of light, t m =mPRT (m=0,1,2,…) represents position slow time;

[0134] R Bi (t m )=R TPm (t m )+R RPm (t m) is the sum of the instantaneous slant distances from the transmitting station to the airborne moving target and the instantaneous slant distance from the receiving station to the airborne moving target. The instantaneous transmitting slant distance from the transmitting station to the target and the instantaneous receiving slant distance from the receiving station to the airborne moving target can be expressed as:

[0135] R TPm (t m )=R TOm (t m )+i T Q;

[0136] R RPm (t m )=R ROm (t m )+i R Q;

[0137] where R TOm (t m ) represents t m The distance from the transmitting station to the center of mass of the moving target at any moment, R ROm (t m ) represents t m The distance from the receiving station to the center of mass of the moving target at any moment, i T The unit vector representing the line of sight from the transmitting station to the center of mass of the aerial moving target, i R The unit vector representing the direction of sight from the receiving station to the mass center of the air moving target, Q represents the vector of any point on the air moving target relative to the mass center of the target, and Q = (x p y p z p ) T , (×) T represents the transposition operation. At this point, we can derive the instantaneous slant range of any point on the aerial moving target as:

[0138] R Bi (t m )=R TOm (t m )+i T (t m )·Q+R ROm (t m )+i R (t m )·Q

[0139] =2R O (t m )+2K(t m )Q·i ME (t m );

[0140] in, Indicates the tth mThe sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the moving target at time t, β(t m )=∠(i T (t m ),i R (t m )) represents the tth m The instantaneous double base angle, Indicates the tth m The cosine value of the instantaneous double base angle at time, Indicates the tth m The unit vector of the equivalent monostatic radar at time .

[0141] At this time, the echo signal can be further described as

[0142]

[0143] Among them, G(t m )=Q·i ME (t m ) represents the tth m A scalar value at the moment.

[0144] Furthermore, under the premise of satisfying the far-field assumption and the short coherent processing interval (CPI), and considering only the influence of the target equivalent translation velocity and equivalent translation acceleration, the system 100 is selected to m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the moving target at the moment R O (t m ) is modeled as:

[0145]

[0146] Among them, R0 represents the initial distance of the instantaneous slant range from the transmitting and receiving dual stations to the target centroid, v0 and a0 represent the instantaneous equivalent translational velocity and equivalent translational acceleration. The existence of these factors mainly causes the echo signal to move across distance units.

[0147] Furthermore, under the premise of satisfying the far-field assumption and shorter CPI, the selected system can further m ) is expanded and approximated by the first-order Taylor series, we can get:

[0148] K(t m )≈K0+K1t m ;

[0149] in,

[0150]

[0151]

[0152] Since the coherent integration time is short, the instantaneous rotation angle θ(t m ) can be described in a short CPI as:

[0153] θ(t m )=θ0+Ωt m

[0154] Where θ0 represents the initial angle and Ω is the angular velocity. For the convenience of analysis, it is assumed that the moment θ0 is selected as the starting moment of the analysis. m The scalar value G(t m ) can be described as:

[0155] G(t m )=P(t m )·i ME (t m )=y P cos(Ωt m )+x P sin(Ωt m );

[0156] Based on the above expansion, the rotation approximate model of bistatic ISAR imaging can be further obtained as follows:

[0157] K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ;

[0158] It should be understood that the above process of establishing the echo model, translation simulation model and rotation simulation model is only an example description, and other methods can also be used to establish the echo model, translation simulation model and rotation simulation model. The embodiment of the present invention does not impose any special restrictions on this.

[0159] S4. Determine a first constraint condition and a second constraint condition of a dual-base angle change rate of the aerial moving target according to the translation simulation model, the rotation simulation model, and the echo model of the aerial moving target.

[0160] Among them, the first constraint condition is the distance constraint, and the second constraint condition is the orientation constraint;

[0161] Specifically, the first constraint condition of the dual base angle change rate is:

[0162]

[0163] in, is the first constraint value of the rate of change of the dual base angle, c is the speed of light, β(t0) is the instantaneous dual base angle at time t0, B is the bandwidth of the transmitted signal, and y p is the initial ordinate of the scattering point on the target relative to the scattering center, T s Accumulate time for coherence.

[0164] The second constraint on the rate of change of the dual base angles is:

[0165]

[0166] in, is the second constraint value of the double base angle change rate, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

[0167] The following uses an example to explain how to determine the first constraint condition and the second constraint condition provided by the embodiment of the present invention.

[0168] In one example, the double base angle change rate constraint is obtained based on the distance traveled constraint.

[0169] After translation compensation, the Bi-ISAR echo signal (echo model) can be described as:

[0170]

[0171] in, is the convolution factor along the fast time τ dimension, δ(·) is the Dirac function, δ r Indicates distance migration;

[0172]

[0173] δ r =(K1y P +K0x P Ω)t m +K1x P Ωt m 2

[0174]

[0175] In order to meet the requirements of high-resolution imaging, the scattering points on the target should not move across the distance unit as much as possible, so the δ after compensation r Usually meet the The demand, when the coherent accumulation time (Coherent Processing Interval, CPI) T s When is small, the target’s rotation angle is relatively small, and the influence of the high-order phase can be ignored. The corresponding constraint can be described as:

[0176]

[0177] The rate of change of the double base angle caused by the distance traveled is expressed as In the expression, simplify and solve the above formula, select the system to obtain the rate of change of the double base angle The first constraint is:

[0178]

[0179] Furthermore, the selection system 100 calculates the maximum boundary value of the bistatic angle change rate under the bistatic ISAR configuration that meets the given phase constraint condition based on the given second-order phase error.

[0180] Specifically, the echo signal is subjected to pulse compression in the range dimension and Doppler analysis in the azimuth dimension. The signal after range pulse compression can be described as:

[0181]

[0182] Performing spectrum analysis on the above formula, we get its spectrum as follows:

[0183]

[0184] in represents the convolution operation factor along the azimuth Doppler dimension v, Represents the azimuth position after bistatic ISAR imaging, and satisfies D(ν) represents the Fourier transform of the azimuthal second-order phase, and FT()× represents the Fourier transform operation.

[0185] In order to meet the azimuth focusing condition, the error caused by the second-order phase cannot exceed Δφ (Δφ is usually less than p / 3). At this time, the following constraints can be further obtained by selecting system 100

[0186]

[0187] By rearranging the above formula, we can obtain that in order to achieve azimuth focusing, the rate of change of the dual base angles needs to satisfy the following constraints, that is, the second constraint is:

[0188]

[0189] S5. Based on the first constraint and the second constraint, select the target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target.

[0190] In some embodiments, see Figure 4 The above S5 specifically includes the following steps:

[0191] S51. Determine a dual-base angle conversion rate threshold based on a first constraint and a second constraint.

[0192] S52. Determine the dual-base angle transformation rate corresponding to each imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target.

[0193] S53: Determine an imaging arc segment whose dual-base angle transformation rate is less than a dual-base angle transformation rate threshold as a target imaging arc segment.

[0194] Among them, the dual base angle conversion rate threshold The formula for determining is:

[0195]

[0196] Specifically, the selection system 100 obtains the optimal dual base angle change rate constraint condition (equivalent to the dual base angle conversion rate threshold) by fusing the dual base angle change rate constraint conditions in the distance dimension and the azimuth dimension.

[0197] In order to achieve good focusing in the range and azimuth dimensions, the rate of change of the double base angles related to the range movement is constrained to (First constraint) and the rate of change of the dual basic angles associated with the azimuth quadratic phase (Second constraint) The minimum fusion criterion is used to merge and the final imaging boundary of Bi-ISAR can be obtained. (Dual base angle conversion rate threshold), the specific expression is as follows:

[0198]

[0199]

[0200] According to the Bi-ISAR imaging boundary determined above, the selection system 100 can further obtain a Bi-ISAR arc segment that meets the requirements.

[0201] The selection rules for the target imaging arc segment are:

[0202]

[0203] Where, l is the imaging arc segment, represents the dual-base angle transformation rate corresponding to the lth imaging arc segment, Represents the Bi-ISAR imaging boundary condition (dual-base-angle transformation rate threshold).

[0204] As can be seen from S1-S5 above, the method provided by the embodiment of the present invention can determine the bistatic ISAR imaging process of an aerial moving target by constructing a bistatic ISAR imaging echo model and a maneuvering model of bistatic ISAR imaging. Finally, by deducing the boundaries of the bistatic angle change rate, the first constraint condition of the distance constraint and the second constraint condition of the azimuth constraint are obtained. Then, the first constraint condition and the second constraint condition are used to select the target imaging arc segment of bistatic ISAR imaging under resolution constraint, thereby effectively improving processing efficiency and imaging quality. In other words, the method provided by the present invention can quickly and quantitatively calculate the bistatic angles and bistatic angle change rate boundary conditions under different observation configurations through the resolution constraint condition, quickly screen out the target imaging arc segment, and optimize the imaging performance of the entire system. In addition, the method provided by the present invention does not require hardware improvements to existing radar equipment, has good flexibility and adaptability, and can meet the use requirements of different usage scenarios.

[0205] In some embodiments, see Figure 5 After the above S5, the method provided by the embodiment of the present invention further includes:

[0206] S61. Set the beam pointing areas of the transmitting station and the receiving station to the same spatial position.

[0207] S62. Set the carrier center frequencies of the transmitting station and the receiving station to the target frequencies.

[0208] S63. Send instructions to the transmitting station and the receiving station, where the instructions are used to instruct the transmitting station and the receiving station to determine high-resolution imaging of the aerial moving target according to the target imaging arc.

[0209] The beneficial effects of the method provided by the embodiment of the present invention are explained below in conjunction with simulation experiments.

[0210] In one example, the system 100 is selected to simulate various bistatic ISAR imaging configurations for different signal resolutions. In a simulation environment, the method provided by the present invention is applied to simulate the maximum boundary conditions of the bistatic angle change rate of different bistatic ISAR imaging configurations under different target rotation speeds and different second-order phase error constraints, so as to verify the beneficial effects of the method provided by the embodiment of the present invention. Figure 6-Figure 15 , and Table 1, Table 2 and Table 3; among which, Figure 6 It is a schematic diagram of the simulation scenario of the dual-base test; Figure 7 This is a schematic diagram of a dot matrix target used for bistatic ISAR imaging; Figure 8 is the double base angle change rate constraint curve in the distance dimension; Figure 9is the double base angle change rate constraint curve in the azimuth dimension; Figure 10 is the rate of change of the dual base angles in the imaging arc segment when the target speed is 50 m / s; Figure 11 is the rate of change of the dual base angles in the imaging arc segment when the target speed is 120 m / s; Figure 12 is the rate of change of the dual base angles in the imaging arc segment when the target speed is 200 m / s; Figure 13 This is the result of two-dimensional point expansion of edge point target when the target speed is 50m / s; Figure 14 This is the two-dimensional point expansion result of the edge point target when the target speed is 120m / s; Figure 15 is the two-dimensional point expansion result of the edge point target when the target speed is 200m / s; Table 1 is the quantitative evaluation result of the edge point target when the target speed is 50m / s; Table 2 is the quantitative evaluation result of the edge point target when the target speed is 120m / s; Table 3 is the quantitative evaluation result of the edge point target when the target speed is 200m / s;

[0211] Table 1

[0212]

[0213] Table 2

[0214]

[0215] Table 3

[0216]

[0217]

[0218] from Figure 6 It can be seen that the double base angle in the test scene is 45°; Figure 7 It can be seen that the shape of the target is a 5×5 dot matrix target; Figure 8 It can be seen that the double base angle change rate constraint curve in the distance dimension becomes smaller as the double base angle increases; Figure 9 It can be seen that the double base angle change rate constraint curve of the azimuth dimension becomes smaller as the double base angle increases; Figure 8 and Figure 9 It can also be seen that according to the minimum fusion criterion proposed in this invention, the constraints of the dual-base angle change rate of Bi-ISAR imaging in 50m / s, 120m / s and 200m / s speed scenarios are 0.35° / s, 0.35° / s and 0.21° / s respectively. Figure 10 It can be seen that the dual base angle change rate in the imaging arc segment when the target speed is 50m / s is 0.14° / s, which is less than the dual base angle change rate constraint of 0.35° / s. Figure 11The double base angle change rate in the imaging arc segment under the scenario of target speed of 120m / s is 0.34° / s, which is still less than the double base angle change rate constraint of 0.35° / s. Figure 12 The change rate of the dual-base angle in the imaging arc segment under the scenario of target speed of 200m / s is 0.57° / s, which exceeds the critical value of 0.23° / s of the constraint condition of the azimuth quadratic phase on the change rate of the dual-base angle. Figure 13 It can be seen that the 2D point spread function of the edge point target is well focused when the target speed is 50 m / s, indicating that a well-focused Bi-ISAR imaging result can be obtained when the imaging arc is below the constraint boundary of the dual base angle change rate. Figure 14 It can be seen that the 2D point spread function of the edge point target is well focused when the target speed is 120 m / s, indicating that the imaging arc segment near the boundary of the dual base angle change rate constraint can still obtain a well-focused Bi-ISAR imaging result; Figure 15 It can be seen that the 2D point spread function of the edge point target with a target speed of 200 m / s has obvious defocusing phenomenon, which means that the imaging arc segment above the dual base angle change rate constraint boundary cannot obtain a well-focused Bi-ISAR imaging result; Figures 13 to 15 The simulation results show that the method for selecting bistatic ISAR imaging arc segments for aerial moving targets based on the bistatic angle change rate constraint proposed in the embodiment of the present invention is effective. The imaging arc segments within the bistatic angle change rate constraint can obtain well-focused Bi-ISAR imaging results; the imaging arc segments outside the bistatic angle change rate constraint cannot obtain well-focused Bi-ISAR imaging results.

[0219] Furthermore, it can be seen from Table 1 that when the air target speed is 50m / s, the four edge point targets have a good focusing effect; it can be seen from Table 2 that when the air target speed is 120m / s, the four edge point targets have a good focusing effect; it can be seen from Table 3 that when the air target speed is 200m / s, the four edge point targets have obvious defocusing phenomenon; the statistical results of the four edge point targets in Tables 1 to 3 show that the bistatic ISAR imaging arc segment selection method for aerial moving targets based on the dual basic angle change rate constraint proposed in the patent of this invention is effective, and the imaging arc segment within the dual basic angle change rate constraint can obtain a well-focused Bi-ISAR imaging result; the imaging arc segment outside the dual basic angle change rate constraint cannot obtain a well-focused Bi-ISAR imaging result.

[0220] Therefore, according to the method of the patent of the present invention, the maximum boundary value of the bistatic angle change rate can be quickly found. Based on this boundary value, we can quickly screen out the bistatic ISAR imaging arc segment and perform high-resolution Bi-ISAR imaging of the moving targets within the arc segment.

[0221] The above mainly introduces the solution of the embodiment of the present invention from the perspective of method. It can be understood that in order to realize the above functions, the system 100 is selected to include at least one of the hardware structure and software modules corresponding to the execution of each function. It should be easy for those skilled in the art to realize that, in combination with the units and algorithm steps of each example described in the embodiment disclosed herein, the embodiment of the present invention can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the embodiment of the present invention.

[0222] In an embodiment of the present invention, the selection system 100 can be divided into functional units according to the above-mentioned method example. For example, the selection system 100 can be divided into functional units corresponding to various functions, or two or more functions can be integrated into one processing unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units. It should be noted that the division of units in the embodiment of the present invention is schematic and is only a logical functional division. In actual implementation, other division methods may be used.

[0223] For example, Figure 16 The hardware structure diagram of a selection system provided by an embodiment of the present invention is shown. The selection system 100 includes: an information acquisition module 110, which is used to obtain the position information of the transmitting station, the receiving station and the airborne moving target, and the position information includes longitude, latitude and altitude; a coordinate conversion module 120, which is used to convert the position information of the transmitting station, the receiving station and the airborne moving target into the coordinates of the Earth-centered Earth-fixed coordinate system; a model establishment module 130, which is used to establish a translation simulation model, a rotation simulation model and an echo model of the airborne moving target; a constraint determination module 140, which is used to determine the first constraint and the second constraint of the dual base angle change rate of the airborne moving target based on the translation simulation model, the rotation simulation model and the echo model of the airborne moving target, wherein the first constraint is a distance constraint and the second constraint is an azimuth constraint; an arc selection module 150, which is used to select the target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the airborne moving target based on the first constraint and the second constraint;

[0224] The first constraint condition for the rate of change of the double base angle is:

[0225]

[0226] Where c is the speed of light, β(t0) is the instantaneous double base angle at time t0, B is the bandwidth of the transmitted signal, and y pis the initial ordinate of the scattering point on the target relative to the scattering center, T s accumulating time for coherence;

[0227] The second constraint on the rate of change of the dual base angles is:

[0228]

[0229] Among them, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

[0230] In a possible implementation of the second aspect, a formula for converting the location information of the transmitting station into coordinates of an Earth-centered Earth-fixed coordinate system is:

[0231]

[0232] The formula for converting the position information of the receiving station into the Earth-centered Earth-fixed coordinate system is:

[0233]

[0234] The formula for converting the position information of an aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is:

[0235]

[0236] Among them, the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,L T ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major semi-axis of the Earth's ellipsoid, a = 6378137 meters.

[0237] The translation simulation model is:

[0238]

[0239] Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m=mPRT (m=0,1,2,…) is the azimuth slow time;

[0240] The rotation simulation model is:

[0241] K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ;

[0242]

[0243] Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time;

[0244] The echo model is:

[0245]

[0246] Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, T p is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

[0247] In a possible implementation of the second aspect, the arc segment selection module 150 is specifically configured to: determine a dual-base angle transformation rate threshold based on the first constraint and the second constraint; determine a dual-base angle transformation rate corresponding to each imaging arc segment based on the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target; and determine an imaging arc segment having a dual-base angle transformation rate less than the dual-base angle transformation rate threshold as a target imaging arc segment;

[0248] Among them, the dual base angle conversion rate threshold The formula for determining is:

[0249]

[0250] In a possible implementation of the second aspect, after the arc selection module 150 selects the target imaging arc according to the geocentric coordinate system coordinates of the transmitting station, the receiving station and the airborne moving target based on the first constraint condition and the second constraint condition, the above-mentioned system also includes a space-time-frequency synchronization module 160 and a high-resolution imaging module 170; the space-time-frequency synchronization module 160 is used to set the beam pointing area of ​​the transmitting station and the receiving station to the same spatial position; and is used to set the carrier center frequency of the transmitting station and the receiving station to the target frequency; the high-resolution imaging module 170 is used to send instructions to the transmitting station and the receiving station, and the instructions are used to instruct the transmitting station and the receiving station to determine the high-resolution imaging of the airborne moving target according to the target imaging arc.

[0251] It should be understood that the specific description of the above optional methods can refer to the above method embodiments, which will not be repeated here. In addition, the explanation of any selection system 100 provided above and the description of the beneficial effects can refer to the above corresponding method embodiments, which will not be repeated here.

[0252] An embodiment of the present invention further provides a computer-readable storage medium storing at least one computer instruction, which is loaded and executed by a processor to implement the methods of each of the above embodiments. For explanations of the relevant contents and descriptions of the beneficial effects of any of the above-mentioned computer-readable storage media, reference can be made to the corresponding embodiments described above and will not be repeated here.

[0253] The embodiment of the present invention further provides a chip. The chip integrates a control circuit and one or more ports for implementing the functions of the selection system 100. Optionally, the functions supported by the chip can be referred to above and will not be repeated here.

[0254] Those skilled in the art will appreciate that all or part of the steps of the above-mentioned embodiments can be implemented by a program to instruct the relevant hardware to complete the program, which can be stored in a computer-readable storage medium. The above-mentioned storage medium can be a read-only memory, a random access memory, etc. The above-mentioned processing unit or processor can be a central processing unit, a general-purpose processor, a specific circuit structure (application specific integrated circuit, ASIC), a microprocessor (digital signal processor, DSP), a field programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof.

[0255] An embodiment of the present invention further provides a computer program product comprising instructions that, when executed on a computer, cause the computer to perform any of the methods described in the above embodiments. The computer program product comprises one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the embodiments of the present invention are fully or partially generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium accessible by a computer or a data storage device such as a server or data center that includes one or more available media. Available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state drives).

[0256] It should be noted that the above-mentioned devices for storing computer instructions or computer programs provided in the embodiments of the present invention, such as but not limited to the above-mentioned memories, computer-readable storage media and communication chips, etc., all have non-transitory properties. Those skilled in the art should be aware that in one or more of the above examples, the functions described in the embodiments of the present invention can be implemented using hardware, software, firmware or any combination thereof. When implemented using software, these functions can be stored in a computer-readable storage medium or transmitted as one or more instructions or codes on a computer-readable storage medium. Computer-readable storage media include computer storage media and communication media, wherein the communication medium includes any medium that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer.

[0257] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A bistatic ISAR imaging arc segment selection method for aerial moving targets, characterized by: The method comprises: Acquiring location information of a transmitting station, a receiving station, and an aerial moving target, wherein the location information includes longitude, latitude, and altitude; Converting the position information of the transmitting station, the receiving station and the aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system; Establishing a translation simulation model, a rotation simulation model and an echo model of the aerial moving target; Determining a first constraint condition and a second constraint condition of a dual-base angle change rate of the airborne moving target based on a translation simulation model, a rotation simulation model, and an echo model of the airborne moving target, wherein the first constraint condition is a distance constraint and the second constraint condition is an orientation constraint; Based on the first constraint and the second constraint, selecting a target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target; The first constraint condition for the rate of change of the double base angle is: Where c is the speed of light, β(t0) is the instantaneous bi-basic angle at time t0, B is the bandwidth of the transmitted signal, and y p is the initial ordinate of the scattering point on the target relative to the scattering center, T s accumulating time for coherence; The second constraint on the rate of change of the dual base angles is: Among them, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

2. The method according to claim 1, characterized in that The formula for converting the position information of the transmitting station into the Earth-centered Earth-fixed coordinate system is: The formula for converting the position information of the receiving station into the coordinates of the Earth-centered Earth-fixed coordinate system is: The formula for converting the position information of the aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is: Among them, the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,L T ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major semi-axis of the Earth's ellipsoid, a = 6378137 meters.

3. The method according to claim 2, characterized in that The translation simulation model is: Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m =mPRT (m=0,1,2,…) is the azimuth slow time; The rotation simulation model is: K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ; Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time; The echo model is: Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, T p is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

4. The method according to claim 3, characterized in that The selecting of the target imaging arc segment based on the first constraint condition and the second constraint condition and according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target includes: Determining a dual base angle conversion rate threshold based on the first constraint and the second constraint; Determine the dual-base angle transformation rate corresponding to each imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the aerial moving target; Determine an imaging arc segment whose dual-base angle transformation rate is less than the dual-base angle transformation rate threshold as a target imaging arc segment; Among them, the dual base angle conversion rate threshold The formula for determining is:

5. The method according to claim 4, characterized in that After selecting the target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target based on the first constraint condition and the second constraint condition, the method further includes: Setting the beam pointing areas of the transmitting station and the receiving station to the same spatial position; Setting the carrier center frequencies of the transmitting station and the receiving station to target frequencies; An instruction is sent to the transmitting station and the receiving station, wherein the instruction is used to instruct the transmitting station and the receiving station to determine a high-resolution imaging of the aerial moving target according to the target imaging arc.

6. A bistatic ISAR imaging arc segment selection system for aerial moving targets, characterized by: The system comprises: An information acquisition module is used to obtain the location information of the transmitting station, the receiving station and the aerial moving target, wherein the location information includes longitude, latitude and altitude; A coordinate conversion module, configured to convert the position information of the transmitting station, the receiving station and the aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system; A model building module, used to build a translation simulation model, a rotation simulation model and an echo model of the aerial moving target; a constraint determination module, configured to determine a first constraint condition and a second constraint condition of a rate of change of a dual basic angle of the aerial moving target based on a translation simulation model, a rotation simulation model, and an echo model of the aerial moving target, wherein the first constraint condition is a distance constraint and the second constraint condition is an orientation constraint; an arc segment selection module, configured to select a target imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target based on the first constraint condition and the second constraint condition; The first constraint condition for the rate of change of the double base angle is: Where c is the speed of light, β(t0) is the instantaneous bi-basic angle at time t0, B is the bandwidth of the transmitted signal, and y p is the initial ordinate of the scattering point on the target relative to the scattering center, T s accumulating time for coherence; The second constraint on the rate of change of the dual base angles is: Among them, x p is the initial horizontal coordinate of the scattering point on the target relative to the scattering center, Ω is the angular velocity, λ is the radar working compensation, and Δθ is the quadratic phase error.

7. The system according to claim 6, characterized in that The formula for converting the position information of the transmitting station into the Earth-centered Earth-fixed coordinate system is: The formula for converting the position information of the receiving station into the coordinates of the Earth-centered Earth-fixed coordinate system is: The formula for converting the position information of the aerial moving target into the coordinates of the Earth-centered Earth-fixed coordinate system is: Among them, the coordinates of the longitude, latitude and altitude of the transmitting station are (B T ,L T ,H T ), the longitude, latitude and altitude coordinates of the receiving station are (B R ,L R ,H R ); the longitude, latitude and altitude coordinates of the aerial moving target are (B O ,L O ,H O ); e is the eccentricity of the Earth, a is the major axis of the Earth's ellipsoid, a = 6378137 meters; The translation simulation model is: Among them, R O (t m ) is the tth m The sum of the instantaneous translational components from the transmitting station and the receiving station to the center of mass of the air moving target at time t, R0 represents the initial distance of the instantaneous slant distance from the transmitting station and the receiving station to the center of mass of the air moving target, v0 is the instantaneous equivalent translational velocity, a0 is the equivalent translational acceleration, t m =mPRT (m=0,1,2,…) is the azimuth slow time; The rotation simulation model is: K(t m )G(t m )=K0y P +(K0x P Ω+K1y P )t m +K1x P Ωt m 2 ; Among them, K(t m ) is the tth m The cosine value of the instantaneous double base angle at time G(t m ) is the tth m The scalar value at the time, β(0) is the instantaneous double base angle at the starting time; The echo model is: Among them, σ is the scattering coefficient of the moving target in the air, τ is the distance time, and f c is the carrier frequency of the radar signal, T p is the pulse width, μ is the modulation frequency of the signal t m =mPRT (m=0,1,2,…) is the azimuth slow time, and j is the imaginary unit.

8. The system according to claim 7, characterized in that The arc segment selection module is specifically used to: Determining a dual base angle conversion rate threshold based on the first constraint and the second constraint; Determine the dual-base angle transformation rate corresponding to each imaging arc segment according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station and the aerial moving target; Determine an imaging arc segment whose dual-base angle transformation rate is less than the dual-base angle transformation rate threshold as a target imaging arc segment; Among them, the dual base angle conversion rate threshold The formula for determining is:

9. The system according to claim 8, characterized in that After the arc selection module selects the target imaging arc according to the Earth-centered Earth-fixed coordinate system coordinates of the transmitting station, the receiving station, and the aerial moving target based on the first constraint condition and the second constraint condition, the system further includes a space-time-frequency synchronization module and a high-resolution imaging module; The space-time-frequency synchronization module is used to set the beam pointing areas of the transmitting station and the receiving station to the same spatial position; and to set the carrier center frequencies of the transmitting station and the receiving station to the target frequency; The high-resolution imaging module is used to send instructions to the transmitting station and the receiving station, wherein the instructions are used to instruct the transmitting station and the receiving station to determine the high-resolution imaging of the aerial moving target according to the target imaging arc.

10. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the bistatic ISAR imaging arc selection method for aerial moving targets according to any one of claims 1 to 5.

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