Carrier dual-beam squint synthetic aperture radar inversion ocean current antenna pointing correction method

Abstract

The invention discloses a carrier dual-beam squint synthetic aperture radar inversion ocean current antenna pointing correction method. The method specifically comprises the following steps: matching POS data with an SAR echo signal; taking the SAR echo signals corresponding to a plurality of continuous pulses as a data block, and storing corresponding POS data at the same time; a data block used for carrier dual-beam squint SAR radar antenna pointing correction is screened out; calculating the component of the total Doppler center frequency of the data block used for correction in the dual-beam radial direction, and calculating the component of the Doppler center frequency caused by the motion and attitude change of the carrier platform in the dual-beam radial direction; calculating the component of the Doppler center frequency of each data block for correction in the dual-beam radial direction after the carrier platform motion and attitude change are removed, converting the component into speed, performing vector synthesis, constructing a cost function, and solving the cost function; according to the method, the ocean current vector inversion quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of marine remote sensing technology, and particularly relates to a method for correcting the pointing of an antenna for inverting ocean currents using a carrier dual-beam oblique-looking synthetic aperture radar. Background Technology

[0002] Synthetic Aperture Radar (SAR), as an active microwave remote sensing system, possesses the unique advantage of all-weather, all-day Earth observation and demonstrates enormous application potential in the field of marine dynamic environment parameter inversion. For measuring the key marine dynamic element of sea surface currents, traditional single-beam SAR systems can only acquire the radial component of the current vector along the radar line of sight, failing to directly obtain complete two-dimensional velocity vector information. This significantly limits its value in marine scientific research and operational applications. To address this issue, dual-beam SAR technology has emerged. This technology simultaneously forms two radar beams with different azimuth directions (i.e., different oblique angles) to observe the same sea surface area sequentially, thereby acquiring two independent radial velocity components. By simultaneously solving for these two components, the complete two-dimensional vector of the current can be inverted. In the process of inverting the current vector from radar echo signals, the Doppler center offset method has become a highly promising technical approach due to its relatively simple radar system and the absence of complex interferometric baselines.

[0003] When using the Doppler center shift method to invert ocean currents, it is necessary to use platform attitude correction methods to calculate and eliminate the Doppler frequency shift caused by the radar platform's own motion and attitude changes, thereby separating the Doppler frequency shift caused by ocean current motion. If the antenna pointing parameters used in this model are inaccurate, it will lead to systematic errors in the calculation of platform motion Doppler, which will seriously contaminate the final ocean current inversion results, or even make them completely invalid.

[0004] However, obtaining accurate antenna pointing parameters is difficult in actual airborne applications. While the radar antenna pointing (including the angle of view and offline angle) can be manually set before flight testing, the actual antenna pointing often deviates from the preset ideal value during actual flight due to the following factors: 1) Platform support deformation: Airborne platforms (such as aircraft) are affected by airflow disturbances and acceleration changes during flight, causing deformation of the support connecting the radar, POS (Position and Orientation System), and fuselage. This deformation is directly transmitted to the antenna, changing its spatial pointing. 2) Installation deviation: The POS used to measure the platform's motion attitude cannot be physically installed at the same point as the radar; there is a certain lever arm between them. The motion attitude measured by the POS is its own attitude; directly using it to calculate the Doppler center shift will introduce geometric errors. Although these factors may seem small in terms of actual antenna pointing deviation, they are not negligible for SAR systems that rely on Doppler frequency shift for precise velocity measurement. Therefore, in order to ensure that the airborne dual-beam slant-look SAR system can retrieve ocean current vectors with high accuracy, an effective antenna pointing correction method must be developed. Summary of the Invention

[0005] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides a method for pointing correction of a carrier dual-beam slanted-looking synthetic aperture radar inverted ocean current antenna.

[0006] Technical solution: This invention discloses a method for pointing correction of an ocean current antenna using a dual-beam slanted-looking synthetic aperture radar, specifically as follows:

[0007] Matching POS data with SAR echo signals based on time; Based on the carrier motion and attitude parameters in the POS data, SAR echo signals with stable carrier motion attitude are selected, and the SAR echo signals corresponding to several consecutive pulses are taken as a data block, and the POS data corresponding to the SAR echo signals are stored in the data block. Based on the observation scene, location, and time, data blocks used for the pointing correction of the dual-beam squint SAR radar antenna of the carrier are selected, which are also the data blocks used for correction. Calculate the component of the total Doppler center frequency of the data block used for correction in the dual-beam radial direction. and , and These represent the components of the total Doppler center frequency of the data block used for correction in the forward and backward beam radial directions, respectively. The slant angle and offline angle of the dual-beam slant-look SAR radar antenna on the carrier are determined. Simultaneously, based on the data blocks used for correction, the components of the Doppler center frequency in the dual-beam radial direction caused by carrier motion and attitude changes are calculated. and ; and These represent the components of the Doppler center frequency in the forward and backward beam radial directions caused by carrier motion and attitude changes, respectively. based on , , as well as The Doppler center frequency component in the dual-beam radial direction of each data block used for correction, after removing carrier motion and attitude changes, is obtained, converted into velocity, and then vector synthesized. Based on the synthesized vector, a cost function is constructed with oblique angle and offline angle as variable parameters; Solving the cost function yields the final angle of view and offline angle of the dual-beam slant-look SAR radar antenna.

[0008] Furthermore, the raw SAR echo data is arranged according to its real and imaginary parts to obtain a complex SAR echo signal. The time information contained in the frame header of the SAR echo signal is extracted, with the time information accurate to milliseconds, and the signal in the frame header is set to zero. Then, the POS data is interpolated to match the time resolution with the echo signal, thereby matching the POS data with the SAR echo signal based on time.

[0009] Furthermore, the feature is that the following filtering conditions are set to filter out SAR echo signals with stable carrier motion attitude: ; ; ; ; ; in, Indicates the speed of the carrier in POS data. Indicates the height of the carrier in POS data. This indicates the maximum carrier speed in POS data. This indicates the maximum carrier height in the POS data. This represents the component of the carrier velocity vector perpendicular to the ground and pointing upwards in the POS data. This indicates the roll angle in the POS data. This represents the pitch angle in the POS data; Based on the set filtering criteria, select the SAR echo signal corresponding to the POS data that meets the filtering criteria.

[0010] Furthermore, all data blocks used for correction are combined into a set of data blocks for correction. The echo signal content of all data blocks used for correction in this set is a uniform sea surface scene. This set includes at least 4 observation directions. The scenes corresponding to all data blocks used for correction should be consistent. The difference between the positions corresponding to all data blocks used for correction is less than a preset position threshold. The difference between the times corresponding to all data blocks used for correction is less than a preset time threshold.

[0011] Furthermore, and The expression is: ; ; in, Represents the phase of a complex number. This indicates the sampling interval of the SAR echo signal in the azimuth direction. , This represents the pulse repetition frequency, where i represents the i-th pulse. and These represent sampling intervals of 1 and 2 respectively. SAR echo signals of the forward and backward beams, Indicates complex conjugation. and These represent the average cross-correlation coefficients of the SAR echo signals of the forward and backward beams, respectively.

[0012] Furthermore, the components of the Doppler center frequency in the dual-beam radial direction caused by the carrier's motion and attitude changes are specifically calculated as follows: Using the carrier's axial direction as the X-axis, the Y-axis perpendicular to the carrier's axial direction to the left as the Y-axis, and the Z-axis perpendicular to the carrier's plane upwards as the Z-axis, a carrier center reference coordinate system is constructed. The pointing of the carrier's dual-beam slant-look SAR radar antenna is then calculated within this coordinate system. ; ; ; in, For offline angle, It is an oblique perspective. For intermediate parameters, and These respectively indicate the pointing directions of the forward and backward beam antennas of the carrier's dual-beam slant-look SAR radar antenna in the carrier's central reference frame; Rotate the carrier center reference coordinate system and the dual-beam slant-looking SAR radar antenna pointing within it to a carrier trajectory reference coordinate system with the carrier as the origin, north as the X-axis, west as the Y-axis, and the vertical downward Z-axis: ; ; ; ; ; in, , and Each represents a transformation matrix for the corresponding coordinate axis. Indicates the roll angle. Indicates pitch angle, Indicates the yaw angle. and These represent the directions of the forward and backward beam antennas of the dual-beam slant-look SAR radar antenna in the carrier trajectory reference frame, respectively. Calculate the radial component of the Doppler center frequency caused by carrier motion and attitude changes in the dual-beam configuration: ; ; ; ; in, Indicates the radar wavelength. and These represent the components of the carrier's motion and attitude change in the forward and backward beam radial directions, respectively. This represents the carrier velocity vector.

[0013] Furthermore, the Doppler center frequency component in the dual-beam radial direction after removing carrier motion and attitude changes for each data block used for correction is specifically obtained as follows: ; ; in, and The components of the Doppler center frequency in the forward and backward beam radial directions after removing the carrier platform's motion and attitude changes from the data blocks used for correction; Use the following formula to and Convert to speed: ; ; in, Indicates the radar wavelength. and These represent the components of the ocean current vector in the forward and backward beam radial directions after removing carrier motion and attitude changes, respectively. Vector synthesis is performed using the following formula: ; ; in, This represents the ocean current vector after removing carrier motion and attitude changes. , and They are respectively Components on the Y and Z axes in the carrier trajectory reference coordinate system express The first dimension express The first dimension express The second dimension, express The second dimension.

[0014] Furthermore, the expression for the cost function J is as follows: ; Where m represents the m-th data block used for correction. This indicates the total number of data blocks used for correction. Indicates the offline angle is oblique angle is The j-th data block used for correction under the combination removes the ocean current vector after carrier motion and attitude changes.

[0015] Furthermore, taking the angle of view and offline angle of the carrier dual-beam squint SAR radar antenna as the starting conditions, an adjustment threshold for the angle of view and offline angle is set. Using the adjustment threshold as a constraint, the minimum value of the cost function is solved. The angle of view and offline angle corresponding to the minimum value of the cost function are the final angle of view and offline angle of the carrier dual-beam squint SAR.

[0016] A computer device includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to implement the steps of the carrier dual-beam slant-looking synthetic aperture radar inversion current antenna pointing correction method.

[0017] Beneficial effects:

[0018] 1. Existing methods for inverting ocean current vectors from SAR data do not consider the ocean current inversion error caused by antenna pointing error. This invention provides an airborne dual-beam slant-look SAR method for correcting the antenna pointing error for ocean current inversion, thereby improving the quality of ocean current vector inversion.

[0019] 2. Existing methods for inverting ocean current vectors using SAR data do not utilize POS data for quality control of echo signals. In contrast, this invention utilizes POS data to remove echo signals with unstable attitudes, thereby improving the quality of ocean current vector inversion.

[0020] 3. Existing methods for retrieving ocean current vectors from SAR data often use land survey data as a zero-Doppler reference. However, land scenes are often non-uniform, which seriously affects the determination of zero-Doppler. This invention utilizes the physical prior that ocean current vectors should remain consistent within a short period of time in the same sea area. It uses sea surface survey data from different observation directions in the same sea area within a short period of time to determine zero-Doppler, thereby improving the quality of ocean current vector inversion. Attached Figure Description

[0021] Figure 1 This is the overall flowchart of the present invention;

[0022] Figure 2 This is a schematic diagram of the attitude change parameters of the airborne platform;

[0023] Figure 3 This is a schematic diagram of the antenna pointing of an airborne dual-beam slant-out SAR radar.

[0024] Figure 4 This is a schematic diagram of the body's central reference frame;

[0025] Figure 5 A schematic diagram of the trajectory reference frame;

[0026] Figure 6 The image shows a comparison between the ocean current vector obtained by the method of this invention and the ocean current vector obtained by the HYCOM model (Hybrid Coordinate Ocean Mode), where (a) is the result of the ocean current vector obtained by the HYCOM model and (b) is the result of the ocean current vector obtained by the method of this invention. Detailed Implementation

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1A general flowchart of the carrier-based dual-beam squint SAR inversion current antenna pointing correction method proposed in this invention is given. The carrier in this embodiment is airborne, and the specific steps are as follows:

[0029] Step 1: Arrange the raw SAR echo data according to the real and imaginary parts to obtain the complex form of the echo signal. Extract and save the time information contained in the frame header in the form of two bits each for hours, minutes, seconds and milliseconds. Then set the entire frame header to zero.

[0030] Step 2: Interpolate the POS data to match the time resolution of the echo signal, and use the time information extracted from the echo signal and the time information in the POS data to match the echo signal and the POS data.

[0031] Step 3: Using the matched POS airborne platform motion parameters (flight altitude, flight speed, etc.) and airborne platform attitude change parameters (roll angle, pitch angle, etc.), filter SAR echo signals with stable airborne platform motion attitude, and divide them into data blocks of 10,000 consecutive pulses, while saving the corresponding POS data. The specific implementation steps are as follows:

[0032] Step 31: Based on the airborne platform motion parameters (flight altitude, flight speed, etc.) measured by POS, select the corresponding SAR echo signals:

[0033] ,

[0034] ,

[0035] ,

[0036] in, Indicates flight speed. Indicates flight altitude. Indicates the maximum flight speed. Indicates the maximum flight altitude. This represents the component of the aircraft's velocity vector perpendicular to the ground and pointing upwards.

[0037] Step 32: Based on the attitude change parameters of the airborne platform measured by POS (roll angle, pitch angle, etc., see the schematic diagram of the attitude change parameters of the airborne platform). Figure 2 ), and filter out the corresponding SAR echo signals:

[0038] ,

[0039] ,

[0040] in, Indicates the roll angle. Indicates the pitch angle.

[0041] Step 33: The echo signals filtered in steps 31 and 32 are saved as a data block for every 10,000 consecutive pulses and corresponding POS data, starting from the initial pulse, and echo signals and POS data with fewer than 10,000 consecutive pulses are discarded.

[0042] Step four involves selecting data blocks from the segmented data blocks for pointing correction of the airborne dual-beam slant-look SAR radar antenna (hereinafter referred to as the correction data blocks) based on the observation location and observation time. The selected data blocks for pointing correction of the airborne dual-beam slant-look SAR radar antenna have the following characteristics: 1) All data blocks containing echo signals must be from a uniform sea surface scene; 2) At least four data blocks from different observation directions must be selected; 3) The observation scene, location, and time corresponding to all data blocks should be as consistent as possible.

[0043] Step 5: Calculate the component of the total Doppler center frequency of the data block used for correction in the dual-beam radial direction according to the following formula:

[0044] ,

[0045] ,

[0046] in, and These represent the components of the total Doppler center frequency in the forward and backward beam radial directions, respectively. Represents the phase of a complex number. This indicates the sampling interval of the SAR echo signal in the azimuth direction. Indicates the pulse repetition frequency. and These represent sampling intervals of 1 and 2 respectively. SAR echo signals of the forward and backward beams, Indicates complex conjugation. and denoted as the average cross-correlation coefficients of the forward and backward beam SAR echo signals, respectively, and i represents the i-th pulse.

[0047] Step six: Point the airborne dual-beam slant-look SAR radar antenna, represented by the slant angle and offline angle that can uniquely determine its pointing in three-dimensional space (see schematic diagram of airborne dual-beam slant-look SAR antenna pointing). Figure 3 , Figure 3 In , , All of these are coordinate axes in a ground coordinate system.

[0048] Step 7: Using the slant angle, offline angle, and data block used for correction from the airborne dual-beam slant-look SAR design, calculate the Doppler center frequency component in the dual-beam radial direction caused by platform motion and attitude changes. The specific implementation steps are as follows:

[0049] Step 71: Construct a carrier center reference coordinate system with the carrier axis direction as the X-axis, the Y-axis perpendicular to the carrier axis to the left as the Y-axis, and the Z-axis perpendicular to the carrier plane upwards as the Z-axis. (In this embodiment, the carrier is airborne, so an airframe center reference system is constructed with the aircraft axis direction as the X-axis, the Y-axis perpendicular to the aircraft axis to the left as the Y-axis, and the Z-axis perpendicular to the aircraft plane upwards as the Z-axis. See the schematic diagram of the reference system.) Figure 4 The pointing of the airborne dual-beam slant-look SAR antenna is defined as follows:

[0050] ,

[0051] ,

[0052] ,

[0053] in, Indicates the offline angle of the radar design. Indicates the oblique angle of radar design. and These represent the pointing directions of the radar's forward and backward beam antennas in the aircraft's central reference frame, respectively. These are intermediate parameters.

[0054] Step 72: Using the POS data in the data block used for calibration, rotate the pointing direction of the airborne dual-beam slant-looking SAR antenna to a track reference frame with the aircraft as the origin, north as the X-axis, west as the Y-axis, and the Z-axis perpendicular to the ground downwards (see schematic diagram of the reference frame). Figure 5 )middle:

[0055] ,

[0056] ,

[0057] ,

[0058] ,

[0059] ,

[0060] in, Indicates the roll angle. Indicates pitch angle, Indicates the yaw angle. , and These represent the transformation matrices, and These represent the orientation of the radar's forward and backward beam antenna designs in the track reference frame, respectively.

[0061] Step 73: Calculate the component of the Doppler center frequency in the dual-beam radial direction caused by the platform's motion and attitude changes using the following formula:

[0062] ,

[0063] ,

[0064] ,

[0065] ,

[0066] in, and These represent the components of platform motion and attitude change in the forward and backward beam radial directions, respectively. Represents the aircraft's velocity vector. and These represent the components of the Doppler center frequency in the forward and backward beam radial directions caused by platform motion and attitude changes, respectively. Indicates the radar wavelength.

[0067] Step 8: Subtract the Doppler center frequency caused by platform motion and attitude change from the total Doppler center frequency of each data block used for correction to obtain the radial component of the Doppler center frequency of each data block after removing platform motion and attitude change in the dual-beam configuration. Convert this component to velocity and then perform vector synthesis. The specific implementation steps are as follows:

[0068] Step 81: Subtract the Doppler center frequency caused by platform motion and attitude changes from the total Doppler center frequency of each data block used for correction using the following formula:

[0069] ,

[0070] ,

[0071] in, and These are the components of the Doppler center frequency in the forward and backward beam radial directions after removing platform motion and attitude changes.

[0072] Step 82, convert the Doppler center frequency into velocity using the following formula:

[0073] ,

[0074] ,

[0075] in, and These represent the components of the ocean current vector in the forward and backward beam radial directions after removing platform motion and attitude changes, respectively.

[0076] Step 83, vector synthesis using the following formula:

[0077] ,

[0078] ,

[0079] in, This represents the ocean current vector after removing platform motion and attitude changes. , and They are respectively The components on the y-axis and x-axis in the carrier trajectory reference coordinate system express The first dimension express The first dimension express The second dimension, express The second dimension.

[0080] Step nine: Using the oblique angle and offline angle as variable parameters, construct a cost function as follows by pairwise equality of the ocean current vectors after removing platform motion and attitude changes from all data blocks used for correction:

[0081] ,

[0082] in, Indicates the sequence number of the data block used for correction. Indicates the number of data blocks used for correction. Indicates the sequence number is The data block used for correction removes the ocean current vector after platform motion and attitude changes.

[0083] Step 10: Using the slant angle and offline angle of the airborne dual-beam slant-looking SAR design as starting conditions, the slant angle and offline angle should be adjusted to no more than [the specified values]. To minimize the cost function, the angle of view and the offline angle taken when the cost function value is minimized are the equivalent pointing angle of the airborne dual-beam slant-look SAR inverted ocean current antenna.

[0084] Using measured data from an airborne experiment conducted on October 30, 2025, in the eastern waters of Hainan, and corresponding HYCOM model ocean current vector data, the effectiveness of the proposed airborne dual-beam oblique-looking SAR method for inverting ocean current antenna pointing correction can be analyzed. The final inverted ocean current vector results are as follows: Figure 6 As shown, the airborne dual-beam slant-look SAR inversion current antenna pointing correction method proposed in this invention can correct the antenna pointing error and the resulting current inversion error, thereby improving the quality of current vector inversion.

[0085] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for pointing correction of a carrier-based dual-beam slanted-looking synthetic aperture radar inverted ocean current antenna, characterized in that, Specifically: Matching POS data with SAR echo signals based on time; Based on the carrier motion and attitude parameters in the POS data, SAR echo signals with stable carrier motion attitude are selected, and the SAR echo signals corresponding to several consecutive pulses are taken as a data block, and the POS data corresponding to the SAR echo signals are stored in the data block. Based on the observation scene, location, and time, data blocks used for the pointing correction of the dual-beam squint SAR radar antenna of the carrier are selected, which are also the data blocks used for correction. Calculate the component of the total Doppler center frequency of the data block used for correction in the dual-beam radial direction. and , and These represent the components of the total Doppler center frequency of the data block used for correction in the forward and backward beam radial directions, respectively. The slant angle and offline angle of the dual-beam slant-look SAR radar antenna on the carrier are determined. Simultaneously, based on the data blocks used for correction, the components of the Doppler center frequency in the dual-beam radial direction caused by carrier motion and attitude changes are calculated. and ; and These represent the components of the Doppler center frequency in the forward and backward beam radial directions caused by carrier motion and attitude changes, respectively. based on , , as well as The Doppler center frequency component in the dual-beam radial direction of each data block used for correction, after removing carrier motion and attitude changes, is obtained, converted into velocity, and then vector synthesized. Based on the synthesized vector, a cost function is constructed with oblique angle and offline angle as variable parameters; Solving the cost function yields the final angle of view and offline angle of the dual-beam slant-look SAR radar antenna.

2. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 1, characterized in that, The raw SAR echo data is arranged according to its real and imaginary parts to obtain a complex SAR echo signal. The time information contained in the frame header of the SAR echo signal is extracted, with the time information accurate to milliseconds, and the signal in the frame header is set to zero. Then, the POS data is interpolated to match the time resolution with the echo signal, thereby matching the POS data with the SAR echo signal based on time.

3. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 1, characterized in that, Set the following filtering criteria to filter out SAR echo signals with stable carrier motion attitude: ； ； ； ； ； in, Indicates the speed of the carrier in POS data. Indicates the height of the carrier in POS data. This indicates the maximum carrier speed in POS data. This indicates the maximum carrier height in the POS data. This represents the component of the carrier velocity vector perpendicular to the ground and pointing upwards in the POS data. This indicates the roll angle in the POS data. This represents the pitch angle in the POS data; Based on the set filtering criteria, select the SAR echo signal corresponding to the POS data that meets the filtering criteria.

4. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 1, characterized in that, All data blocks used for correction are combined into a set of data blocks for correction. The echo signal content of all data blocks used for correction in this set is a uniform sea surface scene. This set includes at least 4 observation directions. The scenes corresponding to all data blocks used for correction should be consistent. The difference between the positions corresponding to all data blocks used for correction should be less than a preset position threshold. The difference between the times corresponding to all data blocks used for correction should be less than a preset time threshold.

5. The method for pointing correction of a carrier-based dual-beam slanted-looking synthetic aperture radar inverted ocean current antenna according to claim 1, characterized in that, and The expression is: ； ； in, Represents the phase of a complex number. This indicates the sampling interval of the SAR echo signal in the azimuth direction. , This represents the pulse repetition frequency, where i represents the i-th pulse. and These represent sampling intervals of 1 and 2 respectively. SAR echo signals of the forward and backward beams, Indicates complex conjugation. and These represent the average cross-correlation coefficients of the SAR echo signals of the forward and backward beams, respectively.

6. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 1, characterized in that, The components of the Doppler center frequency in the dual-beam radial direction caused by the carrier's motion and attitude changes are specifically calculated as follows: Using the carrier's axial direction as the X-axis, the Y-axis perpendicular to the carrier's axial direction to the left as the Y-axis, and the Z-axis perpendicular to the carrier's plane upwards as the Z-axis, a carrier center reference coordinate system is constructed. The pointing of the carrier's dual-beam slant-look SAR radar antenna is then calculated within this coordinate system. ； ； ； in, For offline angle, It is an oblique perspective. For intermediate parameters, and These represent the pointing directions of the forward and backward beam antennas of the carrier dual-beam slant-look SAR radar antenna in the carrier's central reference frame, respectively, and T represents transpose; Rotate the carrier center reference coordinate system and the dual-beam slant-looking SAR radar antenna pointing within it to a carrier trajectory reference coordinate system with the carrier as the origin, north as the X-axis, west as the Y-axis, and the vertical downward Z-axis: ; ; ; ; ; in, , and Each represents a transformation matrix for the corresponding coordinate axis. Indicates the roll angle. Indicates pitch angle, Indicates the yaw angle. and These represent the directions of the forward and backward beam antennas of the dual-beam slant-look SAR radar antenna in the carrier trajectory reference frame, respectively. Calculate the radial component of the Doppler center frequency caused by carrier motion and attitude changes in the dual-beam configuration: ； ； ； ； in, Indicates the radar wavelength. and These represent the components of the carrier's motion and attitude change in the forward and backward beam radial directions, respectively. This represents the carrier velocity vector.

7. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 6, characterized in that, The components of the Doppler center frequency in the dual-beam radial direction after removing carrier motion and attitude changes for each data block used for correction are as follows: ； ； in, and The components of the Doppler center frequency in the forward and backward beam radial directions after removing the carrier platform's motion and attitude changes from the data blocks used for correction; Use the following formula to and Convert to speed: ； ； in, Indicates the radar wavelength. and These represent the components of the ocean current vector in the forward and backward beam radial directions after removing carrier motion and attitude changes, respectively. Vector synthesis is performed using the following formula: ； ； in, This represents the ocean current vector after removing carrier motion and attitude changes. , and They are respectively Components on the Y and Z axes in the carrier trajectory reference coordinate system express The first dimension express The first dimension express The second dimension, express The second dimension.

8. The carrier dual-beam slanted-looking synthetic aperture radar inversion current antenna pointing correction method according to claim 7, characterized in that, The expression for the cost function J is as follows: ； Where m represents the m-th data block used for correction. This indicates the total number of data blocks used for correction. Indicates the offline angle is oblique angle is The j-th data block used for correction under the combination removes the ocean current vector after carrier motion and attitude changes.

9. The method for pointing correction of a carrier-based dual-beam slanted-looking synthetic aperture radar inverted ocean current antenna according to claim 1, characterized in that, Starting with the angle of view and offline angle of the carrier dual-beam squint SAR radar antenna, an adjustment threshold for the angle of view and offline angle is set. Using the adjustment threshold as a constraint, the minimum value of the cost function is solved. The angle of view and offline angle corresponding to the minimum value of the cost function are the final angle of view and offline angle of the carrier dual-beam squint SAR.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the carrier dual-beam slant-look synthetic aperture radar inversion current antenna pointing correction method as described in any one of claims 1 to 9.

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