Single-shot DBF-based multi-beam vector flow observation method and system

Abstract

The application belongs to the technical field of marine vector flow remote sensing observation, and particularly relates to a single-time along-track time-sharing multi-staring vector flow observation method and system based on DBF. The method comprises the following steps: establishing a grid in a target area, setting multi-staring direction separation requirements and pairing time difference thresholds; calculating a single-time observation coverage footprint according to platform and load parameters, determining a maximum interval of repeated observation of the same direction to realize along-track full coverage; generating a scheduling table under the constraints of digital beam forming beam switching and stability ability, so that each grid unit obtains effective observation of at least two types of directions and can be solved; then, line-of-sight velocity is obtained according to the scheduling, and vector flow velocity is solved. The application puts the constraints of coverage continuity and grid solvability in the observation scheduling stage, solves the problems of discontinuous coverage, grid missing and difficulty in obtaining vector flow with single direction in the existing along-track interference observation, and improves the integrity, stability and engineering application value of vector flow acquisition.

Description

Technical Field

[0001] This invention belongs to the field of ocean vector current remote sensing observation technology, specifically a single-time, time-division, multi-slant-look vector current observation method and system based on DBF. Background Technology

[0002] Information on ocean surface vector flow fields is of great significance in applications such as ocean dynamic process research, pollutant drift prediction, marine engineering, and shipping safety. Synthetic aperture radar (SAR) has all-weather, all-day, and wide-area observation capabilities. Among them, in-orbit interferometric SAR can acquire the line-of-sight velocity components of water scatterers on a relatively short time scale, providing an important technical approach for monitoring ocean surface current velocity.

[0003] Since a single observation direction typically only yields the line-of-sight velocity component in one direction, existing techniques usually employ a multi-slant-view observation method to obtain a two-dimensional vector flow field. This involves observing the same region under different slant-view directions and then solving the vector flow by simultaneously solving equations. With the development of technologies such as digital beamforming (DBF), a "time-division multi-slant-view" method, which utilizes the payload to switch beam pointing within different observation windows, can obtain multi-line-of-sight observation data without increasing the number of parallel beam links.

[0004] However, existing multi-slant-view in-orbit interferometric flow measurement methods still have significant shortcomings at the engineering level, mainly reflected in:

[0005] (1) Cover discontinuity and along-track voids: Because the observation adopts discrete time windows (such as the observation time window of segmented illumination) and switches between different sight directions, gaps are likely to appear in the ground cover footprints along the track direction, resulting in some grid cells in the target area being missing, making it difficult to form continuous grid data;

[0006] (2) Single-view grid problem: Even if the target area is completely covered, some grid cells may still only obtain radial observations in a single view, which cannot meet the minimum observation conditions for vector flow calculation. They can only be supplemented by interpolation or extrapolation, thus introducing additional errors and uncertainties.

[0007] (3) Uncontrollable pairing problem: The observation time intervals from different views of the same grid cell lack unified constraints. Inconsistent observation time sequence will reduce the stability of vector solution and affect data consistency;

[0008] (4) Feasibility constraints were not included in the scheduling: The beam switching and stabilization capabilities, turning speed, etc. of the actual load will limit the switching frequency and angle change range between different lines of sight. If the multi-view sequence is designed only from the inversion perspective, the scheduling scheme may be unexecutable or it may be difficult to meet the pairing requirements while ensuring coverage.

[0009] (5) Lack of scheduling methods for “grid data”: Existing technologies focus more on “whether vector flow can be measured”, rather than making “no holes in the grid, solvable in each grid, and achievable in scheduling” a unified hard constraint for the observation stage, which makes it difficult to directly output usable gridded vector flow velocity.

[0010] The adverse consequences of the above problems include: spatial coverage gaps and breaks in the vector velocity of the target area; some meshes are unsolvable or the solution is unstable; and the interpolation repair of missing measurements and single-view meshes in post-processing increases errors and subjectivity, reducing the reliability and data consistency of engineering applications.

[0011] In summary, existing multi-look ATI-SAR vector flow measurement still has shortcomings. In particular, how to design observation window boundaries and DBF scheduling for gridded vector flow acquisition while ensuring continuous spatial coverage and high resolution remains one of the key technical problems that urgently need to be solved. Summary of the Invention

[0012] The purpose of this invention is to provide a single-time, time-division multiple-look vector flow observation method and system based on DBF. This method, without increasing the number of parallel beam links, achieves continuous coverage of the target area and pairable multi-look observations for each grid cell through the calculation and scheduling constraint design of the single observation coverage footprint. It also takes into account the engineering feasibility of beam switching and stabilization capabilities of digital beamforming, thereby overcoming the shortcomings of existing multi-look along-track interferometric flow measurement, such as discontinuous coverage, missing grid measurements or difficulty in obtaining gridded vector flow data from a single look, and difficulty in implementing scheduling schemes.

[0013] The technical solution adopted by this invention to achieve the above objectives is: a single-time, time-division, multi-slant-look vector flow observation method based on DBF, comprising the following steps:

[0014] S1: Establish a unified geographic grid in the target area, wherein the unified geographic grid has a step size along the orbital direction. ;

[0015] S2: Define two different types of oblique viewing directions for vector calculation, and set a time difference threshold for viewing direction pairing; wherein the two different types of oblique viewing directions are denoted as main viewing direction A and main viewing direction B, respectively;

[0016] S3: Calculate the effective ground footprints in the line of sight within a single observation time window burst based on platform and load parameters, and determine the upper limit of the repetition interval of the same line of sight based on the effective ground footprints and grid step size and the full coverage constraint along the same line of sight.

[0017] S4: Using the burst as the smallest scheduling unit, under the premise of satisfying the digital beamforming (DBF) switching capability constraint, oblique sight directions are assigned to each burst along the burst time series, generating an observation scheduling table; the observation scheduling table includes at least two types of oblique sight directions, main sight direction A and main sight direction B, and the two are interspersed in the time series according to preset rules; so that each grid unit in the target area can obtain observations of both types of sight directions A and B and satisfy the sight direction pairing time difference threshold;

[0018] S5: According to the observation schedule, the DBF is controlled sequentially for each burst to form the corresponding oblique line of sight. The line of sight remains unchanged within each burst, and the line velocity of the line of sight is obtained through dual-channel in-orbit interferometry (ATI) within each observation window.

[0019] S6: Incorporate the line-of-sight velocity into a unified geographic grid and calculate the gridded vector velocity.

[0020] Preferably, in step S1, the grid cell is defined as obtaining an observation of a certain line of sight as follows: the effective ground footprints of the corresponding single observation window of the line of sight have a coverage intersection with the grid cell; the same grid cell is allowed to have coverage intersections with the effective ground footprints of multiple observation windows at different times; wherein the effective ground footprints are available coverage areas that meet preset effective thresholds for imaging processing such as signal-to-noise ratio and coherence.

[0021] Preferably, in step S2, the main viewing direction A and the main viewing direction B are located at the boundary viewing directions at both ends of a preset viewing angle range in the azimuth viewing angle dimension, and satisfy the viewing angle separation constraint. ;

[0022] in, , These are the azimuth angles for the main viewing direction A and the main viewing direction B, respectively. A preset threshold is used to ensure the geometric stability of vector solutions.

[0023] Preferably, in steps S2 and S4, the look-pairing time difference threshold is: And for any grid cell Let the grid cells be covered. The set of burst start times for all observations from the main line of sight A is , covering the grid cells The set of burst start times for all main-view B observations is From all possible combinations of the two pairs, select the pair that minimizes the absolute value of the time difference, satisfying the following:

[0024] ;

[0025] Wherein, min is the minimum value function; and the pair of observations can come from two bursts that are not temporally adjacent.

[0026] Preferably, in step S3, the single observation burst specifically refers to the discrete imaging window during which the payload illuminates and receives the Earth within a preset start and end time.

[0027] Preferably, in step S3, the same-view repetition interval is defined as the time interval between two occurrences of the corresponding burst start time in the same view X. X is either A or B; the same-look-direction repetition interval satisfies:

[0028] ;

[0029] in The starting time interval of the kth adjacent burst between two occurrences of the same line of sight X.

[0030] Preferably, in step S3, the same-view-direction along-track full coverage constraint is: for adjacent grid cells along the track direction, there is at least one effective footprint in view direction X that has a coverage intersection with it, that is, the platform's track-direction advance distance between two observations in the same view direction does not exceed the length of a single effective footprint, and an effective overlap margin can be reserved:

[0031] ;

[0032] in, For platform speed, For effective overlap margin ( ), The effective track footprint length for a single burst in the line-of-sight X direction is determined by the platform speed, observation window duration, azimuth beam opening angle, oblique gaze geometry, and effective imaging processing threshold. The observation window duration and platform speed are used to determine the coverage length caused by track motion, the beam opening angle and oblique gaze geometry are used to determine the effective illumination area, and the effective imaging processing threshold is used to eliminate low signal-to-noise ratio or low coherence areas to obtain the effective footprint.

[0033] Preferably, in step S4, the DBF forms a slanted line of sight by loading and switching complex weights on the echoes of the array antenna at the element level or subarray level, and completes the line-of-sight switching between adjacent bursts; the array antenna is preferably a phased array antenna; the DBF switching capability constraints include:

[0034] (a) Line-of-sight switching and settling time constraints: The start time interval between two adjacent different line-of-sight bursts is denoted as... In the In the process, the time used for DBF switching and pointer stabilization is no less than ( );

[0035] (b) Turning angular velocity constraint: The line-of-sight angles of two adjacent bursts must satisfy:

[0036] ;

[0037] in, Let be the azimuth angle assigned to the k-th burst in the time series. The minimum time required for DBF weight loading and pointer stabilization. This represents the maximum steering angular velocity.

[0038] Preferably, in step S4, provided that the observation schedule table includes main line of sight A and main line of sight B and satisfies the constraints of non-empty grid and paired time difference, it supports the insertion of one or more intermediate oblique line of sight. This ensures that at least some grid cells receive line-of-sight velocity observations from three or more different directions, forming a redundant observation set for weighted least squares solution or quality assessment; the intermediate oblique line of sight... The corresponding bursts are allowed to be interspersed with the bursts corresponding to the main view directions A and B in the time series, and Corresponding azimuth angle satisfy:

[0039] .

[0040] A DBF-based single-track time-division multiple-lookout vector flow observation scheduling system includes:

[0041] The grid and threshold settings module is used to create a unified geographic grid and set... and ;

[0042] The footprint and concentric repetition interval upper limit calculation module is used to calculate the effective footprints on the ground and determine the upper limit of the concentric repetition interval;

[0043] The observation scheduling table generation module is used to generate observation scheduling tables that satisfy the non-empty grid constraint, pairing time difference constraint, and DBF switching capability constraint.

[0044] The DBF control and data acquisition module includes an array antenna, a multi-channel receiving link corresponding to each array element channel or sub-array channel of the array antenna, and a processing unit for performing digital beamforming (DBF). The DBF weights are loaded and switched according to the observation schedule to form the corresponding oblique line of sight, so that the line of sight remains unchanged within each observation window, and outputs dual-channel in-orbit interferometry data for ATI processing.

[0045] The ATI velocity measurement and gridded vector solution module is used to perform ATI processing on the dual-channel along-track interferometry data to obtain the line-of-sight velocity in each direction, and to merge the line-of-sight velocity into a unified geographic grid to calculate and output the gridded vector velocity.

[0046] The present invention has the following beneficial effects and advantages:

[0047] 1. Pre-emptive constraints of continuous coverage and solvable grid: The continuity of coverage and solvability of grid are taken as the core constraints in the observation scheduling stage, ensuring that each grid cell obtains effective observations of two different oblique sight directions, reducing missing measurements and single-sight grids from the source, enabling gridded vector velocity to be generated directly, and reducing the dependence on post-processing interpolation and repair.

[0048] 2. Computable scheduling criteria based on footprint and grid step length: The effective ground cover footprint of a single observation is calculated using platform and payload parameters, and the maximum allowable interval for repeated observations in the same line of sight is determined by the grid step length, avoiding coverage holes along the track and improving the continuity and consistency of grid data.

[0049] 3. Realizable and scalable engineering scheduling and output: Engineering constraints such as beam switching and stabilization capabilities of digital beamforming are incorporated into the scheduling generation to ensure that the scheduling table is executable; under the condition of basic solvability, it supports the insertion of intermediate oblique line of sight to form redundant observations, which is used to improve the stability of the solution and carry out quality assessment, thereby enhancing the value of engineering applications. Attached Figure Description

[0050] Figure 1 This is a flowchart of the present invention;

[0051] Figure 2 This is a schematic diagram of an interleaved observation scheduling method for achieving continuous coverage observation along the track according to the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] The DBF-based single-time time-division multiple-look vector flow observation method along the track includes the following steps:

[0054] S1: Establish a unified geographic grid in the target area:

[0055] Select the target area to be observed and establish a regular grid under a unified geographic coordinate system. The grid step size is 5km along the track direction and 5km across the track direction. Define a grid cell to obtain an observation in a certain line of sight as follows: the effective ground footprints of the corresponding single observation window in that line of sight have a coverage intersection with the grid cell; the same grid cell is allowed to have coverage intersections with the effective ground footprints of multiple observation windows at different times; the effective ground footprints are the usable coverage areas that meet the preset effective thresholds for imaging processing such as signal-to-noise ratio and coherence.

[0056] S2: Define two different oblique viewing directions for vector calculation, denoted as main viewing direction A and main viewing direction B. Main viewing directions A and B are located at the boundary viewing directions at both ends of a preset viewing angle range in the azimuth viewing angle dimension, and satisfy the viewing angle separation constraint:

[0057] ;

[0058] in, , These are the azimuth angles for the main viewing direction A and the main viewing direction B, respectively. A preset threshold is used to ensure the geometric stability of vector solutions.

[0059] Set the look-to-pair time difference threshold as follows: And for any grid cell Let the grid cells be covered. The set of burst start times for all observations from the main line of sight A is , covering the grid cells The set of burst start times for all main-view B observations is From all possible combinations of the two pairs, select the pair that minimizes the absolute value of the time difference, satisfying the following:

[0060] ;

[0061] Wherein, min is the minimum value function; and the pair of observations can come from two bursts that are not temporally adjacent.

[0062] S3: Calculate the effective ground footprints within a single observation window (burst) for the line of sight based on platform and load parameters. Combine these effective ground footprints with the grid step size, and determine the upper limit of the same-line-of-sight repetition interval based on the full coverage constraint along the track. The same-line-of-sight repetition interval is defined as the time interval between two occurrences of the same line of sight X corresponding to the start time of the burst. X is either A or B; the same-look-direction repetition interval satisfies:

[0063] ;

[0064] in The time interval between the start of the k-th adjacent burst between two occurrences of the same line of sight X.

[0065] The co-line track-wide coverage constraint is as follows: for adjacent grid cells along the track direction, there must be at least one effective footprint in the X-direction that overlaps with it, meaning that the platform's track-wide advance distance between two observations in the same line of sight does not exceed the length of a single effective footprint, and an effective overlap margin can be reserved.

[0066] ;

[0067] in, For platform speed, For effective overlap margin (0 ), The effective track footprint length for a single burst in the line-of-sight X direction is determined by the platform speed, observation window duration, azimuth beam opening angle, oblique gaze geometry, and effective imaging processing threshold. The observation window duration and platform speed are used to determine the coverage length caused by track motion, the beam opening angle and oblique gaze geometry are used to determine the effective illumination area, and the effective imaging processing threshold is used to eliminate low signal-to-noise ratio or low coherence areas to obtain the effective footprint.

[0068] S4: Using a burst as the smallest scheduling unit, and under the premise of satisfying the digital beamforming (DBF) switching capability constraints, oblique viewing directions are assigned to each burst along the burst time series, generating an observation scheduling table; the observation scheduling table includes at least two types of oblique viewing directions, main viewing direction A and main viewing direction B, and the two are interleaved in the time series according to preset rules; so that each grid cell in the target area obtains observations of both types of viewing directions A and B and satisfies the viewing direction pairing time difference threshold; the DBF forms oblique viewing directions by loading and switching complex weights on the echoes of the array antenna at the element level or subarray level, and completes the viewing direction switching between adjacent bursts; the array antenna is preferably a phased array antenna; the DBF switching capability constraints include:

[0069] (a) Line-of-sight switching and settling time constraints: The start time interval between two adjacent different line-of-sight bursts is denoted as... In the In the process, the time used for DBF switching and pointer stabilization is no less than ( );

[0070] (b) Steering angular velocity constraint: The line-of-sight angles of two adjacent bursts satisfy:

[0071] ;

[0072] in, Let be the azimuth angle assigned to the k-th burst in the time series. The minimum time required for DBF weight loading and pointer stabilization. This represents the maximum steering angular velocity.

[0073] Provided that the observation schedule includes main line of sight A and main line of sight B and satisfies the constraints of non-empty grid and paired time difference, it supports the insertion of one or more intermediate oblique lines of sight. This ensures that at least some grid cells receive line-of-sight velocity observations from three or more different directions, forming a redundant observation set for weighted least squares solution or quality assessment; the intermediate oblique line of sight... The corresponding bursts are allowed to be interspersed with the bursts corresponding to the main view directions A and B in the time series, and Corresponding azimuth angle satisfy:

[0074] ;

[0075] S5: According to the observation schedule, the DBF is controlled sequentially for each burst to form the corresponding oblique line of sight. The line of sight remains unchanged within each burst, and the line velocity of the line of sight is obtained through dual-channel in-orbit interferometry (ATI) within each observation window.

[0076] S6: Incorporate the line-of-sight velocity into a unified geographic grid and calculate the gridded vector velocity.

[0077] like Figure 2 This is a schematic diagram of an AB staggered observation scheduling. The effective footprints of adjacent bursts along the track direction are connected or have overlapping areas. For any grid cell, there are two different observation directions, provided by two bursts that are not adjacent in time, thus achieving continuous grid coverage and solvability of each cell.

[0078] DBF-based single-track time-division multiple-look vector flow observation scheduling system:

[0079] This embodiment presents a DBF-based single-track time-division multiple-lookout vector flow observation scheduling system for implementing the above method. The system mainly includes the following functional modules:

[0080] Grid and threshold setting module:

[0081] It is used to establish a unified geographic grid based on the target area, set the grid step size along the track, the grid step size across the track, and the time difference threshold for line-of-sight pairing; and can set constraint parameters such as line-of-sight separation requirements, providing a unified prior for footprint calculation, observation scheduling and vector flow solution.

[0082] Footprint and same-view repetition interval upper limit calculation module:

[0083] This is used to calculate the effective ground cover footprint for a single observation window in each oblique line of sight based on platform and load parameters, and to determine the maximum allowable interval for repeated observations in the same line of sight by the footprint and grid step size, in order to constrain the continuity of coverage along the track in the same line of sight and avoid coverage gaps or missing grids.

[0084] Observation scheduling table generation module:

[0085] The table is used to generate an observation schedule, which includes at least a line-of-sight sequence, observation window boundaries, and corresponding beam control parameters. It ensures that each grid cell in the target area receives two types of line-of-sight observations and meets the pairing time difference threshold, while also satisfying the feasibility constraints of digital beamforming, such as beam switching and stabilization capabilities and turning speed. When the constraints are not met, the line-of-sight sequence or observation window boundaries are adjusted and the schedule is regenerated.

[0086] The DBF control and data acquisition module includes an array antenna, a multi-channel receiving link corresponding to each array element channel or sub-array channel of the array antenna, and a processing unit for performing digital beamforming (DBF). The DBF weights are loaded and switched according to the observation schedule to form the corresponding oblique line of sight, so that the line of sight remains unchanged within each observation window, and outputs dual-channel in-orbit interferometry data for ATI processing.

[0087] ATI Velocity Measurement and Mesh Vector Solving Module:

[0088] The system is used to perform ATI processing on the dual-channel along-track interferometric data to obtain the line-of-sight velocity for each line of sight, and to merge the line-of-sight velocity into a unified geographic grid. For each grid cell, two lines of sight are paired and two-dimensional vector flow is calculated. When there are redundant line-of-sight observations, weighted fusion or overdetermined calculation can be used to output quality assessment indicators. Finally, gridded vector flow data and quality layer are output.

[0089] The system described in this embodiment can be deployed on a spaceborne platform, or it can be extended to airborne or other platforms; as long as it has the ability to perform in-orbit interferometric velocimetry, controllable switching of digital beamforming, and corresponding gridded data generation, the method of this invention can be realized.

[0090] In summary, by bringing the constraints of along-track coverage continuity, grid solvability, and beam switching feasibility to the observation scheduling stage, this invention can effectively avoid data gaps caused by coverage holes and single-line grids, thereby improving the integrity, stability, and engineering application value of gridded vector flow data.

[0091] In this specification, the present invention has been described with reference to specific embodiments. The above embodiments are preferred embodiments of this application and are not intended to limit the scope of the invention. It should be noted that the present invention is not limited to the specific embodiments described above. Improvements, variations, combinations, substitutions, etc., made by those skilled in the art without departing from the principles of the present invention are all within the scope of protection claimed in the claims of this invention.

[0092] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A single-time, time-division, multi-slant-look vector flow observation method along a track based on DBF, characterized in that, Includes the following steps: S1: Establish a unified geographic grid in the target area. The unified geographic grid has a step size along the track direction. ; S2: Define two different types of oblique viewing directions for vector calculation, and set a time difference threshold for viewing direction pairing; wherein the two different types of oblique viewing directions are denoted as main viewing direction A and main viewing direction B, respectively; S3: Calculate the effective ground footprints in different line of sight within a single observation time window burst based on platform and load parameters, and determine the upper limit of the repetition interval in the same line of sight based on the effective ground footprints and grid step size and the full coverage constraint along the track in the same line of sight. The same-view-direction along-track full coverage constraint is as follows: for adjacent grid cells along the track direction, there must be at least one effective footprint in view direction X that overlaps with it, that is, the platform's track-direction advance distance between two observations in the same view direction does not exceed the length of a single effective footprint, and an effective overlap margin can be reserved: ； in, For platform speed, For effective overlap margin, , The effective track footprint length for a single burst in the line-of-sight X direction is determined by the platform speed, observation window duration, azimuth beam opening angle, oblique gaze geometry, and effective imaging processing threshold. The observation window duration and platform speed are used to determine the coverage length caused by track motion, the beam opening angle and oblique gaze geometry are used to determine the effective illumination area, and the effective imaging processing threshold is used to eliminate low signal-to-noise ratio or low coherence areas to obtain the effective footprint. S4: Using a single observation time window burst as the smallest scheduling unit, and under the premise of satisfying the digital beamforming (DBF) switching capability constraint, oblique viewing directions are assigned to each single observation time window burst along the time sequence of the single observation time window burst, generating an observation scheduling table; the observation scheduling table includes at least two types of oblique viewing directions, main viewing direction A and main viewing direction B, and the two are interspersed in the time sequence according to preset rules; so that each grid cell in the target area obtains observations of both types of viewing directions A and B and satisfies the viewing direction pairing time difference threshold; The digital beamforming (DBF) forms a slanted line of sight by loading and switching complex weights on the echoes of the array antenna at the element level or subarray level, and completes line-of-sight switching between adjacent bursts; the switching capability constraints of the digital beamforming (DBF) include: (a) Line-of-sight switching and settling time constraints: The time interval between the start times of the bursts of two adjacent single observation windows for different lines of sight is denoted as... The time for digital beamforming (DBF) switching and pointing stabilization is not less than , ; (b) Turning angular velocity constraint: The line-of-sight angles of two adjacent single-observation burst windows satisfy: ； in, Let be the azimuth angle assigned to the k-th single observation window burst in the time series. The minimum time required for DBF weight loading and pointer stabilization. This is the maximum steering angular velocity; S5: According to the observation schedule, the digital beamforming (DBF) is sequentially controlled to form the corresponding oblique line of sight for each single observation window burst. The line of sight remains unchanged within each single observation window burst, and the line of sight velocity is obtained through dual-channel in-orbit interferometry (ATI) within each observation window. S6: Incorporate the line-of-sight velocity into a unified geographic grid and calculate the gridded vector velocity.

2. The single-time, time-division, multi-slant-look vector flow observation method based on DBF according to claim 1, characterized in that, In step S1, a grid cell is defined to obtain an observation of a certain line of sight as follows: the effective ground footprints of the corresponding single observation window of the line of sight have a coverage intersection with the grid cell; the same grid cell is allowed to have coverage intersections with the effective ground footprints of multiple observation windows at different times; wherein the effective ground footprints must satisfy the available coverage area of ​​the effective imaging processing threshold.

3. The single-time, time-division, multi-slant-look vector flow observation method based on DBF according to claim 1, characterized in that, In step S2, the main viewing direction A and the main viewing direction B are located at the boundary viewing directions at both ends of a preset viewing angle range in the azimuth viewing angle dimension, and satisfy the viewing angle separation constraint: ； in, , These are the azimuth angles for the main viewing direction A and the main viewing direction B, respectively. This is a preset threshold used to ensure the geometric stability of vector solutions.

4. The single-time, time-division multiple-look vector flow observation method along the track based on DBF according to claim 1, characterized in that, In steps S2 and S4, the look-to-pair time difference threshold is: And for any grid cell Let the grid cells be covered. The set of single observation window burst start times for all observations in the main line of sight A is , covering the grid cells The set of burst start times for all main-view B observations is From all possible combinations of the two pairs, select the pair that minimizes the absolute value of the time difference, satisfying the following: ; Wherein, min is the minimum value function; and a pair of observations can come from two single observation windows that are not temporally adjacent.

5. The single-time, time-division multiple-look vector flow observation method along the track based on DBF according to claim 1, characterized in that, In step S3, the single observation time window burst specifically refers to the discrete imaging window in which the payload illuminates and receives the Earth within a preset start and end time.

6. The single-time, time-division, multi-slant-look vector flow observation method based on DBF according to claim 1, characterized in that, In step S3, the same-direction repetition interval is defined as the time interval between the start times of two occurrences of the same line of sight X corresponding to the single observation window burst. X is either A or B; the same-look-direction repetition interval satisfies: ； in Let be the time interval between the start of the k-th adjacent single observation window burst between two occurrences of the same line of sight X. This represents the number of observation windows between two occurrences of the same line of sight X.

7. The single-time, time-division, multi-slant-look vector flow observation method based on DBF according to claim 1, characterized in that, In step S4, provided that the observation schedule table includes main line of sight A and main line of sight B and satisfies the constraints of non-empty grid and paired time difference, it is possible to insert one or more intermediate oblique line of sight. This ensures that at least some grid cells receive line-of-sight velocity observations from three or more different directions, forming a redundant observation set for weighted least squares solution or quality assessment; the intermediate oblique line of sight... The corresponding single observation burst allows for the interleaving of single observation bursts corresponding to the main line of sight A and B in the time series, and Corresponding azimuth angle satisfy: 。 8. A DBF-based single-track time-division multiple-lookout vector flow observation scheduling system implementing the method of any one of claims 1 to 7, characterized in that, include: The grid and threshold settings module is used to create a unified geographic grid and set... and ; The footprint and concentric repetition interval upper limit calculation module is used to calculate the effective footprints on the ground and determine the upper limit of the concentric repetition interval; The observation scheduling table generation module is used to generate observation scheduling tables that satisfy the non-empty grid constraint, pairing time difference constraint, and DBF switching capability constraint. The DBF control and data acquisition module includes an array antenna, a multi-channel receiving link corresponding to each array element channel or sub-array channel of the array antenna, and a processing unit for performing digital beamforming (DBF). The unit loads the multi-channel echo data according to the observation schedule and switches the DBF weights to form the corresponding oblique line of sight, so that the line of sight remains unchanged within each observation window, and outputs dual-channel in-orbit interferometry data for ATI processing. The ATI velocity measurement and gridded vector solution module is used to perform ATI processing on the dual-channel along-track interferometry data to obtain the line-of-sight velocity in each direction, and to merge the line-of-sight velocity into a unified geographic grid to calculate and output the gridded vector velocity.

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