A bistatic radar space synchronization method based on clutter locking

Abstract

The application discloses a double-base radar space synchronization method based on clutter locking, which comprises the following steps: firstly, a double-base radar space synchronization model is established, model parameter initialization is completed, uniform sea clutter surface target echo is obtained, two-dimensional scanning is performed on the sea clutter area, echo filtering and uniformization processing are performed, the azimuth and pitch angle of the beam alignment moment are estimated, the irradiation target area is changed, multiple sets of alignment moment angles are obtained, a double-base relative position positioning equation is established, the position error of the transmitting station and the receiving station is introduced, the positioning equation is optimized and solved, the relative position of the double-base platform is obtained, the double-base beam angle is recalculated, and the double-base radar space synchronization is realized. Compared with the existing space synchronization method, the method does not depend on the precision of the aircraft platform inertial navigation system, effectively solves the problem that the double-base beam is difficult to realize space synchronization in the actual flight process in the actual working environment, and cannot use navigation information, and the inertial navigation system has a large cumulative error in the long-time flight process.

Description

Technical Field

[0001] This invention belongs to the field of bistatic radar space synchronization technology, specifically relating to a bistatic radar space synchronization method based on clutter locking. Background Technology

[0002] Bistatic radar, with its separate transmit and receive platforms, offers advantages over monostatic radar, including longer detection range, more flexible observation scenarios, and stronger anti-jamming capabilities. Spatial synchronization, one of the three major synchronization issues in bistatic radar configurations, is a necessary prerequisite for receiving echo signals. Therefore, research and exploration into spatial synchronization of bistatic radar has considerable practical value.

[0003] Existing space synchronization methods require precise measurement systems for positioning and attitude determination, as well as precise servo control systems. A complete navigation and attitude measurement system is formed by combining three measurement devices: Global Positioning System (GPS), Inertial Navigation System (INS), and Inertial Measurement Unit (IMU). This system provides real-time and stable, precise measurements of the motion platform's information. The results of this measurement system will guide the aircraft's flight and antenna pointing, thereby achieving space synchronization.

[0004] However, these space synchronization methods rely excessively on attitude information and the accuracy of the inertial navigation system. In real-world operating environments, electromagnetic interference can cause GPS and other satellite positioning equipment to malfunction, preventing the platform from achieving high-precision positioning. Furthermore, the inertial navigation system can accumulate significant errors during long-term flight. Therefore, these methods struggle to meet the requirements of high-precision positioning, leading to substantial errors in subsequent space synchronization. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a bistatic radar space synchronization method based on clutter locking, which solves the problem that the platform cannot use navigation information or the inertial navigation system accumulates large errors, resulting in unsatisfactory space synchronization effects in practical engineering.

[0006] The technical solution adopted in this invention is: a bistatic radar space synchronization method based on clutter locking, the specific steps of which are as follows:

[0007] S1. Establish a bistatic radar space synchronization model and complete the initialization of model parameters;

[0008] S2. Obtain the target echo on the uniform sea clutter surface, and sequentially change the azimuth and elevation angles of the transmitting station to perform a two-dimensional scan of the sea clutter region;

[0009] S3. Filter and homogenize the echo, and estimate the azimuth and elevation angle at the moment of beam alignment based on the echo energy.

[0010] S4. Change the target area to obtain multiple sets of alignment time angles;

[0011] S5. Establish the relative position positioning equation of the two base stations, introduce the position error of the transmitting station and the receiving station, and use the differential evolution algorithm to optimize and solve the positioning equation to obtain the relative position of the two base stations.

[0012] S6. Recalculate the dual-base beam angle to achieve spatial synchronization of the dual-base radar.

[0013] Furthermore, step S1 is specifically as follows:

[0014] In a Cartesian coordinate system, the center point of the scene is point O. The coordinates of the transmitting station and the receiving station are respectively , The elevation and azimuth angles of the transmitting and receiving stations relative to the center point of the scene at azimuth 0 are respectively... , , , The position information of the carrier platform is represented by the coordinates of the scene center point combined with the bi-base angle information, as shown in the following expression:

[0015]

[0016] in, , , , , This represents a combined expression of the coordinates and angles of the receiving station and the transmitting station.

[0017] Furthermore, step S2 is specifically as follows:

[0018] S21. Obtain target echoes from uniform sea clutter wavefronts;

[0019] The transmitting station is set to transmit a linear frequency modulated (LFM) signal, and the coordinates of each scattering point within the illumination area are: The echo signal received by the receiving station from the surface target After demodulation:

[0020]

[0021] in, , These represent the envelopes in the range and azimuth directions, respectively. , These represent time in the azimuth direction and time in the distance direction, respectively. Indicates wavelength. It represents the speed of light. Indicates the frequency modulation of the distance-to-LFM signal. Indicates the azimuth synthesis aperture time. Indicates the time of beam center. This indicates the history of bistatic distance.

[0022] S22, Two-dimensional scan of the sea clutter region;

[0023] Selecting the target echo from a uniform sea clutter surface, the initial elevation and azimuth angles of the transmitting and receiving stations relative to the scene center point at azimuth 0 time are determined based on the coarse positioning of the inertial navigation system. , , , As an initial angle, the receiving station operates in spotlight mode, and the transmitting station operates within the range of the radar beamwidth. The target area is scanned by changing the azimuth and elevation angles at intervals of °, resulting in a two-dimensional echo scanning matrix.

[0024] in, The size is determined by the required synchronization accuracy.

[0025] Furthermore, step S3 is specifically as follows:

[0026] S31, Azimuth filtering processing;

[0027] Range-time domain-azimuth frequency domain signal is obtained by performing range pulse compression and azimuth Fourier transform on the echo signal. Sea clutter exhibits a banded azimuth spectrum in the azimuth frequency domain. An azimuth filter is constructed based on the echo azimuth spectrum. Filter out the spectral components of non-oceanic clutter in the scene.

[0028]

[0029] in, Indicates the azimuth frequency.

[0030] S32, Echo signal homogenization;

[0031] Histograms were used to perform probability statistics on the echo signals, and different probabilities were set according to different sea surface characteristics. As a confidence interval, strong points in the target area that exceed the threshold are filtered out, thus homogenizing the target scene.

[0032] The signal is obtained after inverse Fourier transform in azimuth and filtering out strong points. .

[0033] S33. Optimal beam alignment direction angle estimation;

[0034] In the time domain, the filtered and homogenized target echoes are accumulated based on their amplitudes to estimate the energy of the echo signal, and the correspondence between the obtained signal energy and the azimuth and time is determined. :

[0035]

[0036] The signal energy is smoothed, and the peak value of the smoothed echo signal is used as the moment of dual-platform radar beam alignment, from which the azimuth and elevation angles at that moment are obtained. , , , That is, the beam angle of the transmitting and receiving stations when the beams are aligned.

[0037] Furthermore, step S4 is specifically as follows:

[0038] Change the illumination area of ​​the receiving station and repeat N times. Steps S2 and S3 yield multiple sets of spatial synchronization beam pointing angles. , , , set , , , and the coarse positioning results of the transmitting and receiving stations at the corresponding times. , .

[0039] Furthermore, step S5 is specifically as follows:

[0040] S51. Establish the relative position positioning equations of the two bases;

[0041] In a single experiment, the coarse positioning of the transmitting station and the receiving station is as follows: , Assuming there is no positioning error and the bistatic beam centers are perfectly aligned, the positioning equations for the relative positions of the bistatic beams with respect to the elevation and azimuth angles are constructed as follows:

[0042]

[0043] S52. Reconstruct the equations for the transmitting and receiving stations regarding the aircraft position and beam pointing angle;

[0044] Introducing positional errors of the transmitting and receiving stations , The corrected beam alignment time will then be the location of the transmitting station. Location of receiving station for:

[0045]

[0046] Substitute the azimuth and elevation angles obtained in step S4 at the relative target beam alignment time. , , , set , , , Then, according to step S51, the equations for the transmitting station and receiving station with respect to the carrier aircraft position and beam pointing angle are reconstructed, and the corresponding beam centers of the transmitting station and receiving station are then obtained. , :

[0047]

[0048] S53. Use the beam centers of the transmitting and receiving stations estimated in step S52. , Multiple sets of experimental beam centers were obtained. , The set is Therefore, the positioning error estimation problem is modeled as a system of nonlinear equations with the six positioning errors of the transceiver stations as variables:

[0049]

[0050] This equation can be transformed into an optimization problem for solution. Based on the least squares criterion, a genetic evolutionary algorithm is used to optimize the positions of the two basic units according to the following constraints:

[0051]

[0052] S54, steps S52-S54 constitute an iterative optimization process. This iterative process is repeated until the variables converge, yielding the relative positions of the transmitting and receiving stations. .

[0053] Furthermore, step S6 is specifically as follows:

[0054] Step S5 obtains the relative position of the carrier platform. A coordinate system is constructed with the launch station as the origin, and the coordinates of the launch station and the receiving station are obtained as follows: , Then, for the location of the center point of the scene of interest Based on the bistatic radar space synchronization model proposed in step S1:

[0055]

[0056] Calculate the synchronous elevation and azimuth beam pointing angles of the corresponding transmitting and receiving stations. , , , This invention achieves spatial synchronization of bistatic radar. The beneficial effects of this invention are as follows: First, a bistatic radar spatial synchronization model is established, model parameters are initialized, target echoes from a uniform sea clutter surface are acquired, a two-dimensional scan of the sea clutter region is performed, and the echoes are filtered and homogenized. The azimuth and elevation angles at the beam alignment moment are estimated, the target illumination area is changed, multiple sets of alignment moment angles are obtained, a bistatic relative position positioning equation is established, the position errors of the transmitting and receiving stations are introduced, the positioning equation is optimized and solved, the relative position of the bistatic platform is obtained, and the bistatic beam angle is recalculated to achieve bistatic radar spatial synchronization. Compared with existing spatial synchronization methods, this invention does not rely on the accuracy of the carrier platform's inertial navigation system, effectively solving the problem that in actual flight operations, navigation information cannot be used in the actual working environment, and the inertial navigation system accumulates large errors during long-term flight, making it difficult to achieve spatial synchronization of bistatic beams. Attached Figure Description

[0057] Figure 1 This is a flowchart of a bistatic radar space synchronization method based on clutter locking according to the present invention.

[0058] Figure 2 This is a geometric diagram of the bistatic radar used in an embodiment of the present invention.

[0059] Figure 3 This diagram illustrates the changes in the beam scanning center in an embodiment of the present invention.

[0060] Figure 4 This is a two-dimensional time-domain echo signal diagram after step S2 in an embodiment of the present invention.

[0061] Figure 5 This is a comparison diagram of the spectrum before and after azimuth filtering in step S31 of this embodiment of the invention.

[0062] Figure 6 This is a diagram illustrating the estimation process of the synchronous beam pointing angle in step S33 of this embodiment of the invention.

[0063] Figure 7 This is an error diagram for estimating the azimuth and elevation angles of different targets in an embodiment of the present invention.

[0064] Figure 8 This is a diagram showing the error variation when the optimization algorithm solves for the relative positions of the two bases in an embodiment of the present invention. Detailed Implementation

[0065] The method of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0066] like Figure 1The flowchart of a bistatic radar space synchronization method based on clutter locking according to the present invention is shown below. The specific steps are as follows:

[0067] S1. Establish a bistatic radar space synchronization model and complete the initialization of model parameters;

[0068] S2. Obtain the target echo on the uniform sea clutter surface, and sequentially change the azimuth and elevation angles of the transmitting station to perform a two-dimensional scan of the sea clutter region;

[0069] S3. Filter and homogenize the echo, and estimate the azimuth and elevation angle at the moment of beam alignment based on the echo energy.

[0070] S4. Change the target area to obtain multiple sets of alignment time angles;

[0071] S5. Establish the relative position positioning equation of the two base stations, introduce the position error of the transmitting station and the receiving station, and use the differential evolution algorithm to optimize and solve the positioning equation to obtain the relative position of the two base stations.

[0072] S6. Recalculate the dual-base beam angle to achieve spatial synchronization of the dual-base radar.

[0073] In this embodiment, step S1 is specifically as follows:

[0074] In a Cartesian coordinate system, the center point of the scene is point O. The coordinates of the transmitting station and the receiving station are respectively , The elevation and azimuth angles of the transmitting and receiving stations relative to the center point of the scene at azimuth 0 are respectively... , , , The position information of the carrier platform is represented by the coordinates of the scene center point combined with the bi-base angle information, as shown in the following expression:

[0075]

[0076] in, , , , , This represents a combined expression of the coordinates and angles of the receiving station and the transmitting station.

[0077] The bistatic SAR geometry used in this embodiment is as follows: Figure 2 As shown in Table 1, the parameters of the bistatic radar system used are presented.

[0078] Table 1

[0079]

[0080] The coordinates of the transmitting station and the receiving station at azimuth 0 at time 0 are respectively... , The speeds are respectively m / s and m / s; the transmitted signal is the center frequency. The signal bandwidth is 17.142 GHz. 38MHz, pulse width The signal is a 35µs linear frequency modulated signal with a directional pulse transmission frequency (PRF) of 1000Hz. Additionally, the electromagnetic wave velocity... 3×10 8 m / s.

[0081] In this embodiment, step S2 is specifically as follows:

[0082] S21. Obtain target echoes from uniform sea clutter wavefronts;

[0083] In this simulation, the target point is set to (0,0,0), the transmitter emits a linear frequency modulated (LFM) signal, and the coordinates of the scattering points within the illumination area are... The echo signal received by the receiving station from the surface target After demodulation:

[0084]

[0085] in, , These represent the envelopes in the range and azimuth directions, respectively. , These represent time in the azimuth direction and time in the distance direction, respectively. Indicates wavelength. It represents the speed of light. Indicates the frequency modulation of the distance-to-LFM signal. Indicates the azimuth synthesis aperture time. Indicates the time of beam center. This indicates the history of bistatic distance.

[0086] S22, Two-dimensional scan of the sea clutter region;

[0087] Selecting the target echo from a uniform sea clutter surface, the initial elevation and azimuth angles of the transmitting and receiving stations relative to the scene center point at azimuth 0 time are determined based on the coarse positioning of the inertial navigation system. , , , As an initial angle, the receiving station operates in spotlight mode, and the transmitting station operates within the range of the radar beamwidth, i.e. ( , ), ( , The target area is scanned by changing the azimuth and elevation angles at 0.1° intervals to obtain a two-dimensional echo scanning matrix.

[0088] The changes in beam center during the scanning process and the echo signal after pulse compression are as follows: Figure 3 , Figure 4 As shown.

[0089] In this embodiment, step S3 is specifically as follows:

[0090] S31, Azimuth filtering processing;

[0091] Range-time domain-azimuth frequency domain signal is obtained by performing range pulse compression and azimuth Fourier transform on the echo signal. Sea clutter exhibits a banded azimuth spectrum in the azimuth frequency domain. An azimuth filter is constructed based on the echo azimuth spectrum. Filter out the spectral components of non-oceanic clutter in the scene.

[0092]

[0093] in, Indicates the azimuth frequency.

[0094] The azimuth spectrum of the echo signal before and after filtering is as follows: Figure 5 As shown, Figure 5 (a) is the pre-filter spectrum. Figure 5 (b) is the azimuth spectrum after filtering.

[0095] S32, Echo signal homogenization;

[0096] To eliminate the energy influence of some strong points in the echo, histograms are used to perform probability statistics on the echo signal. Different probabilities are set as confidence intervals according to different sea surface characteristics. In this embodiment, 95% is used as the confidence interval to filter out strong points in the target area that exceed the threshold, thereby homogenizing the target scene.

[0097] The signal is obtained after inverse Fourier transform in azimuth and filtering out strong points. .

[0098] S33. Optimal beam alignment direction angle estimation;

[0099] In the time domain, the filtered and homogenized target echoes are accumulated based on their amplitudes to estimate the energy of the echo signal, and the correspondence between the obtained signal energy and the azimuth and time is determined. :

[0100]

[0101] The signal energy is smoothed, and the peak value of the smoothed echo signal is used as the moment of dual-platform radar beam alignment, from which the azimuth and elevation angles at that moment are obtained. , , , That is, the beam angle of the transmitting and receiving stations when the beams are aligned.

[0102] The difference between the signal energy and the distance to the center of the dual-base beam is as follows: Figure 6 As shown.

[0103] In this embodiment, step S4 is specifically as follows:

[0104] By changing the illumination area of ​​the receiving station and repeating steps S2 and S3 six times, multiple sets of space synchronization beam pointing angles are obtained. , , , set , , , and the coarse positioning results of the transmitting and receiving stations at the corresponding times. , .

[0105] The estimation error of the spatial synchronous beam pointing angle of multiple targets is as follows: Figure 7 As shown, Figure 7 (a) represents the azimuth estimation error. Figure 7 (b) Pitch angle estimation error.

[0106] In this embodiment, step S5 is specifically as follows:

[0107] S51. Establish the relative position positioning equations of the two bases;

[0108] In a single experiment, the coarse positioning of the transmitting station and the receiving station is as follows: , Assuming there is no positioning error and the bistatic beam centers are perfectly aligned, the positioning equations for the relative positions of the bistatic beams with respect to the elevation and azimuth angles are constructed as follows:

[0109]

[0110] S52. Reconstruct the equations for the transmitting and receiving stations regarding the aircraft position and beam pointing angle;

[0111] Introducing positional errors of the transmitting and receiving stations , The corrected beam alignment time will then be the location of the transmitting station. Location of receiving station for:

[0112]

[0113] Substitute the azimuth and elevation angles obtained in step S4 at the relative target beam alignment time. , , , set , , , Then, according to step S51, the equations for the transmitting station and receiving station with respect to the carrier aircraft position and beam pointing angle are reconstructed, and the corresponding beam centers of the transmitting station and receiving station are then obtained. , :

[0114]

[0115] S53. Use the beam centers of the transmitting and receiving stations estimated in step S52. , Multiple sets of experimental beam centers were obtained. , The set is Therefore, the positioning error estimation problem is modeled as a system of nonlinear equations with the six positioning errors of the transceiver stations as variables:

[0116]

[0117] This equation can be transformed into an optimization problem for solution. Based on the least squares criterion, a genetic evolutionary algorithm is used to optimize the positions of the two basic units according to the following constraints:

[0118]

[0119] S54, steps S52-S54 constitute an iterative optimization process. This iterative process is repeated until the variables converge, yielding the relative positions of the transmitting and receiving stations. .

[0120] A schematic diagram showing the relative positions of the two bases obtained by combining multiple sets of errors is shown below. Figure 8 As shown, Figure 8 (a) represents the relative position error in the x-direction during the iterative process. Figure 8 (b) Relative position error in the y-direction during the iterative process.

[0121] In this embodiment, step S6 is specifically as follows:

[0122] Step S5 obtains the relative position of the carrier platform, constructs a coordinate system with the launch station as the origin, and obtains the coordinates of the launch station and the receiving station as follows: , Then, for the location of the center point of the scene of interest Based on the bistatic radar space synchronization model proposed in step S1:

[0123]

[0124] Calculate the synchronous elevation and azimuth beam pointing angles of the corresponding transmitting and receiving stations. , , , This enables bi-base radar spatial synchronization.

[0125] In summary, compared with existing space synchronization methods, the method of the present invention does not rely on the accuracy of the carrier platform's inertial navigation system, and effectively solves the problem that it is difficult to achieve space synchronization of bistatic beams in actual flight operations, where navigation information cannot be used in the actual working environment and the inertial navigation system accumulates large errors during long-term flight.

[0126] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A bistatic radar space synchronization method based on clutter locking, the specific steps of which are as follows: S1. Establish a bistatic radar space synchronization model and complete the initialization of model parameters; S2. Obtain the target echo on the uniform sea clutter surface, and sequentially change the azimuth and elevation angles of the transmitting station to perform a two-dimensional scan of the sea clutter region; S3. Filter and homogenize the echo, and estimate the azimuth and elevation angle at the moment of beam alignment based on the echo energy. S4. Change the target area to obtain multiple sets of alignment time angles; Change the illumination area of ​​the receiving station and repeat. Steps S2 and S3 yield multiple sets of spatial synchronization beam pointing angles. , , , set , , , and the coarse positioning results of the transmitting and receiving stations at the corresponding times. , ; S5. Establish the relative position positioning equation of the two base stations, introduce the position error of the transmitting station and the receiving station, and use the differential evolution algorithm to optimize and solve the positioning equation to obtain the relative position of the two base stations. S51. Establish the relative position positioning equations of the two bases; In a single experiment, the coarse positioning of the transmitting station and the receiving station is as follows: , Assuming there is no positioning error and the bistatic beam centers are perfectly aligned, the positioning equations for the relative positions of the bistatic beams with respect to the elevation and azimuth angles are constructed as follows: ； S52. Reconstruct the equations for the transmitting and receiving stations regarding the aircraft position and beam pointing angle; Introducing positional errors of the transmitting and receiving stations , The corrected beam alignment time will then be the location of the transmitting station. Location of receiving station for: ； Substitute the azimuth and elevation angles obtained in step S4 at the relative target beam alignment time. , , , set , , , Then, according to step S51, the equations for the transmitting station and receiving station with respect to the carrier aircraft position and beam pointing angle are reconstructed, and the corresponding beam centers of the transmitting station and receiving station are then obtained. , : ； S53. Use the beam centers of the transmitting and receiving stations estimated in step S52. , Multiple sets of experimental beam centers were obtained. , The set is Therefore, the positioning error estimation problem is modeled as a system of nonlinear equations with the six positioning errors of the transceiver stations as variables: ； This equation can be transformed into an optimization problem for solution. Based on the least squares criterion, a genetic evolutionary algorithm is used to optimize the positions of the two basic units according to the following constraints: ； S54, steps S52-S54 constitute an iterative optimization process. This iterative process is repeated until the variables converge, yielding the relative positions of the transmitting and receiving stations. ; S6. Recalculate the dual-base beam angle to achieve spatial synchronization of the dual-base radar.

2. The bistatic radar space synchronization method based on clutter locking according to claim 1, characterized in that, The specific steps of S1 are as follows: In a Cartesian coordinate system, the center point of the scene is point O. The coordinates of the transmitting station and the receiving station are respectively , The elevation and azimuth angles of the transmitting and receiving stations relative to the center point of the scene at azimuth 0 are respectively... , , , The position information of the carrier platform is represented by the coordinates of the scene center point combined with the bi-base angle information, as shown in the following expression: ； in, , , , , This represents a combined expression of the coordinates and angles of the receiving station and the transmitting station.

3. The bistatic radar space synchronization method based on clutter locking according to claim 1, characterized in that, Step S2 is as follows: S21. Obtain target echoes from uniform sea clutter wavefronts; The transmitting station is set to transmit a linear frequency modulated (LFM) signal, and the coordinates of each scattering point within the illumination area are: The echo signal received by the receiving station from the surface target After demodulation: ； in, , These represent the envelopes in the range and azimuth directions, respectively. , These represent time in the azimuth direction and time in the distance direction, respectively. Indicates wavelength. Represents the speed of light; Indicates the frequency modulation of the distance-to-LFM signal. Indicates the azimuth synthesis aperture time. Indicates the time of beam center; Indicates the history of bistatic distance; S22, Two-dimensional scan of the sea clutter region; Selecting the target echo from a uniform sea clutter surface, the initial elevation and azimuth angles of the transmitting and receiving stations relative to the scene center point at azimuth 0 time are determined based on the coarse positioning of the inertial navigation system. , , , As an initial angle, the receiving station operates in spotlight mode, and the transmitting station operates within the range of the radar beamwidth. The target area is scanned by changing the azimuth and elevation angles at intervals of °, resulting in a two-dimensional echo scanning matrix. in, The size is determined by the required synchronization accuracy.

4. The bistatic radar space synchronization method based on clutter locking according to claim 1, characterized in that, Step S3 is as follows: S31, Azimuth filtering processing; Range-time domain-azimuth frequency domain signal is obtained by performing range pulse compression and azimuth Fourier transform on the echo signal. Sea clutter exhibits a banded azimuth spectrum in the azimuth frequency domain. An azimuth filter is constructed based on the echo azimuth spectrum. Filter out the spectral components of non-sea clutter in the scene; ； in, Indicates the azimuth frequency; S32, Echo signal homogenization; Histograms were used to perform probability statistics on the echo signals, and different probabilities were set according to different sea surface characteristics. As a confidence interval, strong points in the target area that exceed the threshold are filtered out, thus homogenizing the target scene; The signal is obtained after inverse Fourier transform in azimuth and filtering out strong points. ; S33. Optimal beam alignment direction angle estimation; In the time domain, the filtered and homogenized target echoes are accumulated based on their amplitudes to estimate the energy of the echo signal, and the correspondence between the obtained signal energy and the azimuth and time is determined. : ； The signal energy is smoothed, and the peak value of the smoothed echo signal is used as the moment of dual-platform radar beam alignment, from which the azimuth and elevation angles at that moment are obtained. , , , That is, the beam angle of the transmitting and receiving stations when the beams are aligned.

5. The bistatic radar space synchronization method based on clutter locking according to claim 1, characterized in that, Step S6 is as follows: Step S5 obtains the relative position of the carrier platform. A coordinate system is constructed with the launch station as the origin, and the coordinates of the launch station and the receiving station are obtained as follows: , Then, for the location of the center point of the scene of interest Based on the bistatic radar space synchronization model proposed in step S1: ； Calculate the synchronous elevation and azimuth beam pointing angles of the corresponding transmitting and receiving stations. , , , This enables bi-base radar spatial synchronization.

Images