Satellite-borne sliding spotlight SAR azimuth beam scanning control method and system based on uniform variable speed scanning

Abstract

The invention relates to the technical field of satellite-borne synthetic airborne radar imaging, in particular to a satellite-borne sliding spotlight SAR azimuth beam scanning control method and system based on uniform variable speed scanning, and the method comprises the steps: setting an azimuth beam starting scanning angular velocity and an azimuth beam stopping scanning angular velocity according to an imaging scene and an azimuth geometric resolution; setting an azimuth beam scanning angular acceleration based on the initial scanning angular velocity and the termination scanning angular velocity of the azimuth beam according to the length of the imaging surveying and mapping band in the sliding bunching mode and the change of the azimuth change rate; and according to the azimuth beam scanning angular acceleration, adjusting the beam scanning speed of the satellite-borne SAR in a sliding bunching mode so as to realize multi-azimuth resolution imaging of an imaging scene. According to the method, the high-value target can obtain more radar beam irradiation time and better azimuth resolution while all targets meet the resolution design requirement, the requirement for the azimuth beam scanning capability of the satellite-borne SAR system can be reduced to a certain extent, and the complexity and the manufacturing cost of the satellite-borne SAR system are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of satellite-borne synthetic airborne radar imaging, and in particular to a satellite-borne sliding spotlight SAR azimuth beam scanning control method and system based on uniformly variable speed scanning. Background Art

[0002] Spaceborne synthetic aperture radar (SAR) uses the flight orbit of spacecraft (satellite / space shuttle) to transmit electromagnetic waves and receive echo signals of target scenes, and obtains high-resolution microwave images reflecting the electromagnetic scattering characteristics of ground objects through radar pulse compression processing and synthetic aperture processing. Compared with optical satellite imaging, spaceborne SAR has the advantages of all-day, all-weather, and certain vegetation / surface penetration. Therefore, it is often used in many fields such as national defense security, ship detection, disaster monitoring, and agricultural, forestry and animal husbandry production estimation. Geometric resolution is one of the most core technical indicators of spaceborne SAR. High resolution is helpful for subsequent radar image interpretation and remote sensing applications. Sliding beam mode is the most important imaging mode for spaceborne SAR to achieve high-resolution imaging. This mode uses azimuth beam scanning to increase the radar beam's residence time on the target, thereby improving the azimuth geometric resolution of spaceborne SAR. At present, all domestic and foreign SAR satellites in orbit have sliding beam high-resolution imaging mode.

[0003] In response to different requirements of spaceborne SAR imaging technical indicators, such as geometric resolution, azimuth imaging scene width, observation angle, paired echo amplitude, etc., SAR satellites often need to adopt different azimuth beam scanning strategies. Reasonable design of the azimuth beam scanning strategy of the sliding beam mode is one of the core keys for spaceborne SAR to achieve high-quality and high-resolution imaging. The traditional spaceborne SAR sliding beam mode adopts a fixed scanning angular velocity according to the azimuth geometric resolution requirements. The fixed azimuth beam scanning angular velocity makes the azimuth resolution of the entire imaging surveying band basically the same. As the azimuth mapping length increases, the azimuth imaging scene often contains observation objects with different geometric resolution observation requirements, such as sea-land boundary scenes, urban-rural integration scenes, specific military scenes, etc. The azimuth beam uniform speed scanning cannot achieve different azimuth geometric resolutions for the same imaging scene. Summary of the invention

[0004] To this end, the present invention provides a satellite-borne sliding spotlight SAR azimuth beam scanning control method and system based on uniformly variable speed scanning, which solves the quality problem of complex imaging scenes with multiple existing geometric resolution requirements, so as to meet the application requirements of imaging scenes with generally monotonous and gradually complex geometric resolutions such as the sea-land boundary, urban-rural boundary, etc.

[0005] According to the design scheme provided by the present invention, on the one hand, a method for controlling azimuth beam scanning of a space-borne sliding spotlight SAR based on uniformly variable speed scanning is provided, comprising:

[0006] The azimuth beam start scanning angular velocity and the end scanning angular velocity are set according to the imaging scene and the azimuth geometric resolution, and the azimuth beam scanning angular acceleration is set based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change of the sliding beam mode;

[0007] The beam scanning speed of the spaceborne SAR sliding spotlight mode is adjusted according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

[0008] As a spaceborne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, setting the azimuth beam start scanning angular velocity and the end scanning angular velocity comprises:

[0009] The azimuth resolution improvement factor corresponding to the starting azimuth resolution and the ending azimuth resolution is set according to the starting azimuth resolution, the ending azimuth resolution, the beam width, the wavelength and the azimuth pulse pressure broadening coefficient of the gradual imaging scene;

[0010] Based on the azimuth resolution improvement factor and utilizing the relationship between the azimuth scanning angular velocity and the azimuth resolution, the azimuth starting beam scanning angular velocity and the ending scanning angular velocity are obtained.

[0011] As a spaceborne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, setting the azimuth beam scanning angular acceleration comprises:

[0012] The azimuth beam moving speed in the corresponding sliding beam mode is obtained according to the azimuth beam starting scanning angular velocity and ending scanning angular velocity and the shortest slant distance from the imaging scene center to the satellite track;

[0013] According to the azimuth beam start scanning angular velocity and end scanning angular velocity and the imaging mapping strip length, the time for the center of the radar beam footprint to pass through the entire mapping strip in azimuth is obtained;

[0014] The azimuth beam scanning angular acceleration is obtained based on the time when the center of the radar beam footprint passes through the entire surveying strip in azimuth, the azimuth beam start scanning angular velocity, and the azimuth beam end scanning angular velocity.

[0015] As a spaceborne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, adjusting the beam scanning speed of the spaceborne SAR sliding spotlight mode according to the azimuth beam scanning angular acceleration comprises:

[0016] Set the initial scanning angular velocity and the final scanning angular velocity of the azimuth beam, and set the radar azimuth beam scanning duration and scanning start time according to the relative geometric relationship between the satellite and the imaging scene;

[0017] Constructing the beam scanning angular velocity variation expression according to the azimuth beam initial scanning angular velocity and the terminal scanning angular velocity, the scanning duration and the scanning start time;

[0018] The azimuth beam pointing at different azimuth times is obtained according to the beam scanning angular velocity variation expression, and the azimuth beam pointing is discretized;

[0019] The number of radar dwell pulses for different azimuth beam orientations is set according to the discretized azimuth beam orientations.

[0020] As a spaceborne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, setting the azimuth beam initial scanning angular velocity and the termination scanning angular velocity comprises:

[0021] The synthetic aperture time is set according to the beam width of azimuth focused imaging, the speed of the spaceborne SAR beam footprint moving along the ground when no azimuth beam scanning is performed, the shortest slant distance from the center of the imaging scene to the satellite track, and the azimuth resolution improvement factor;

[0022] The initial scanning angular velocity and the terminal scanning angular velocity of the azimuth beam are obtained according to the synthetic aperture time and the azimuth beam scanning angular velocity.

[0023] As a spaceborne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, setting the radar azimuth beam scanning duration and scanning start time comprises:

[0024] Obtaining sliding spotlight mode radar imaging time according to synthetic aperture time;

[0025] Calculate the start and end angles of the azimuth beam scan according to the initial scanning angular velocity and the end scanning angular velocity of the azimuth beam and the radar imaging time;

[0026] The start and end angles of the azimuth beam scan are used to obtain the start time of the radar beam scan.

[0027] As a space-borne sliding spotlight SAR azimuth beam scanning control method based on uniformly variable speed scanning of the present invention, further, the azimuth beam pointing is discretized, comprising:

[0028] The azimuth beam pointing is discretized according to the beam jump of the antenna azimuth beam scanning, so as to calculate the number of radar dwell pulses of a single azimuth beam pointing according to the discretized azimuth beam pointing.

[0029] On the other hand, the present invention also provides a spaceborne sliding spotlight SAR azimuth beam scanning control system based on uniform speed scanning, comprising: a scanning angular acceleration setting module and an azimuth resolution imaging module, wherein:

[0030] A scanning angular acceleration setting module is used to set the azimuth beam start scanning angular velocity and the end scanning angular velocity according to the imaging scene and the azimuth geometric resolution, and to set the azimuth beam scanning angular acceleration based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change in the sliding beam focusing mode;

[0031] The azimuth resolution imaging module is used to adjust the beam scanning speed of the satellite-borne SAR sliding beam mode according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

[0032] Beneficial effects of the present invention:

[0033] 1. The present invention introduces azimuth beam scanning angular acceleration to adjust the beam scanning speed of the satellite-borne SAR sliding beam mode, so that targets at different azimuth positions in the imaging scene can achieve different azimuth geometric resolutions, thereby meeting the application requirements of different resolutions for different targets in the same scene.

[0034] 2. The present invention adjusts the radar beam's beam dwell time on different ground objects by scanning the azimuth beam at a uniform speed. While all targets meet the resolution design requirements, high-value targets can obtain more radar beam illumination time and better azimuth resolution.

[0035] 3. The azimuth beam uniformly variable speed scanning method of the present invention can reduce the requirements for the azimuth beam scanning capability of the spaceborne SAR system to a certain extent, thereby reducing the complexity and cost of the spaceborne SAR system, and has a good application prospect in the imaging of the spaceborne SAR system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the azimuth beam scanning control process of the space-borne sliding spotlight SAR based on uniformly variable speed scanning in the embodiment;

[0037] Figure 2 It is a schematic diagram of the principle of the azimuth beam scanning control algorithm in the embodiment;

[0038] Figure 3 It is a schematic diagram of the uniformly variable speed scanning sliding spotlight SAR scanning model in the embodiment. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and technical solutions.

[0040] The design and implementation of more reasonable azimuth resolution of targets within the entire mapping band can help improve the imaging observation efficiency of the spaceborne SAR sliding beam mode. By studying complex imaging scenes with various geometric resolution requirements, it can be found that the geometric resolution requirements of most imaging scenes generally present a monotonous gradient, such as the boundary between land and sea, the boundary between urban and rural areas, etc. For this reason, the embodiments of the present invention refer to Figure 1 As shown, a method for controlling azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning is provided, comprising:

[0041] S101, setting the azimuth beam start scanning angular velocity and the end scanning angular velocity according to the imaging scene and the azimuth geometric resolution, and setting the azimuth beam scanning angular acceleration based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change in the sliding beam focusing mode.

[0042] Specifically, the azimuth resolution improvement factor corresponding to the starting azimuth resolution and the ending azimuth resolution can be set according to the starting azimuth resolution, the ending azimuth resolution, the beam width of the azimuth focused imaging, the wavelength and the azimuth pulse pressure broadening coefficient of the gradual imaging scene; based on the azimuth resolution improvement factor and utilizing the relationship between the azimuth scanning angular velocity and the azimuth resolution, the azimuth starting beam scanning angular velocity and the ending scanning angular velocity are obtained.

[0043] like Figure 2 In the algorithm shown, the azimuth scanning angular velocity and angular acceleration required at the beam start time, the actual azimuth scanning angular velocity at the beam start and end times, the azimuth beam start and end pointing angles and the beam scanning start time are calculated in sequence according to the input radar parameters, and then the number of radar dwell pulses pointed by the beam in a single direction is obtained according to the calculation results.

[0044] The initial azimuth resolution ρ can be calculated by formula (1): a,st and the final position resolution ρ a,end The corresponding azimuth resolution improvement factor A st and A end .

[0045]

[0046] Among them, θ a is the beam width of azimuth focused imaging, λ is the wavelength, and k is the azimuth pulse pressure broadening coefficient introduced by SAR imaging processing, windowing to suppress side lobes, and non-ideal factors.

[0047] According to the relationship between the azimuth scanning angular velocity and the azimuth resolution, the azimuth scanning angular velocity w corresponding to the requirement is calculated using formula (2): r,st and w r,end :

[0048]

[0049] Among them, v g is the moving speed of the spaceborne SAR beam footprint along the ground when no azimuth beam scanning is performed, R c It is the shortest slant distance from the center of the imaging scene to the satellite track.

[0050] The azimuth beam moving speed in the corresponding sliding beam mode can be obtained according to the azimuth beam starting scanning angular velocity, the ending scanning angular velocity and the shortest slant distance from the center of the imaging scene to the satellite track; the time for the center of the radar beam footprint to pass through the entire mapping strip in azimuth can be obtained according to the azimuth beam starting scanning angular velocity, the ending scanning angular velocity and the length of the imaging mapping strip; the azimuth beam scanning angular acceleration can be obtained based on the time for the center of the radar beam footprint to pass through the entire mapping strip in azimuth and the azimuth beam starting scanning angular velocity and the azimuth beam ending scanning angular velocity.

[0051] According to the required azimuth scanning angular velocity w r,st and w r,end , use formula (3) to calculate the azimuth beam moving speed v in the corresponding sliding beam mode f,st and v f,end :

[0052] v f,st =1-w r,st ·R c

[0053] v f,end =1-w r,end ·R c (3)

[0054] According to the required azimuth scanning angular velocity w r,st and w r,end and the length of the imaging swath, and use formula (4) to calculate the time T for the center of the radar beam footprint to pass through the entire swath in azimuth:

[0055]

[0056] Among them, L g is the length of the azimuth survey strip.

[0057] According to the total scanning time T and the required azimuth scanning angular velocity w r,st 、w r,end , use formula (5) to calculate the azimuth beam scanning angular acceleration a:

[0058]

[0059] S102, adjusting the beam scanning speed of the spaceborne SAR sliding spotlight mode according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

[0060] Specifically, by setting the initial scanning angular velocity and the terminal scanning angular velocity of the azimuth beam, and setting the radar azimuth beam scanning duration and the scanning start time according to the relative geometric relationship between the satellite and the imaging scene; constructing an expression for the change of the beam scanning angular velocity according to the initial scanning angular velocity and the terminal scanning angular velocity of the azimuth beam, the scanning duration and the scanning start time; obtaining the azimuth beam pointing at different azimuth times according to the expression for the change of the beam scanning angular velocity, and discretizing the azimuth beam pointing; setting the number of radar dwell pulses for different azimuth beam pointings according to the discretized azimuth beam pointing.

[0061] Aspect resolution improvement factor A st and A end , calculate the corresponding synthetic aperture time T s,st and T s,end , they can be expressed as:

[0062]

[0063] According to the synthetic aperture time T s,st 、T s,end and the azimuth beam scanning angular acceleration a, calculate the corresponding beam scanning angular velocity w r,s and w r,e , they can be expressed as:

[0064]

[0065] According to the total scanning time T and the synthetic aperture time T s,st 、T s,end , calculate the sliding beam mode radar imaging time T ima , which can be expressed as:

[0066]

[0067] According to the beam scanning angular velocity w r,s 、w r,e and radar imaging time T ima , calculate the start and end angles θ of the azimuth beam scan s and θ e , they can be expressed as:

[0068] θ s =1 / 4(w r,s +w r,e )·T ima

[0069] θ e =-1 / 4(w r,s +w r,e )·T ima (9)

[0071] According to the start and end angles θ of the azimuth beam scan s and θ e , calculate the start time t of radar beam scanning s , which can be expressed as:

[0072]

[0073] Among them, t 0 is the moment when the subsatellite point is parallel to the starting position of the imaging scene, such as Figure 3 shown.

[0074] The change process of beam scanning angular velocity is converted into an expression, which can be expressed as:

[0075] w r (t) = w r,st +a·(tt s ) (11)

[0076] Among them, t∈[t s ,t s +T ima ] indicates direction time.

[0077] Calculate the azimuth beam pointing θ(t) at different azimuth times under the condition of continuous scanning of the azimuth beam, which can be expressed as

[0078]

[0079] According to the beam jump q used in the antenna azimuth beam scanning, the azimuth scanning angle is discretized, and the discretized azimuth beam pointing is

[0080]

[0081] Where round(·) is the rounding factor.

[0082] According to the discretized azimuth beam pointing θ q (t), calculate the number of radar dwell pulses N pointed by a single azimuth beam p , which can be expressed as:

[0083]

[0084] Where round(·) is the rounding factor, q is the beam jump, and PRF is the pulse repetition frequency.

[0085] Further, based on the above method, an embodiment of the present invention also provides a spaceborne sliding spotlight SAR azimuth beam scanning control system based on uniformly variable speed scanning, comprising: a scanning angular acceleration setting module and an azimuth resolution imaging module, wherein:

[0086] A scanning angular acceleration setting module is used to set the azimuth beam start scanning angular velocity and the end scanning angular velocity according to the imaging scene and the azimuth geometric resolution, and to set the azimuth beam scanning angular acceleration based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change in the sliding beam focusing mode;

[0087] The azimuth resolution imaging module is used to adjust the beam scanning speed of the satellite-borne SAR sliding beam mode according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

[0088] By introducing the azimuth beam scanning angular acceleration and adjusting the beam scanning speed of the spaceborne SAR sliding beam mode, different azimuth geometric resolutions can be achieved for targets at different azimuth positions in the imaging scene, thereby meeting the application requirements of imaging with multiple azimuth resolutions in complex imaging scenes.

[0089] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0090] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0091] The units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person of ordinary skill in the art may use different methods to implement the described functions for each specific application, but such implementation is not considered to be beyond the scope of the present invention.

[0092] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, a disk or an optical disk. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits, and accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of software function modules. The present invention is not limited to any specific form of combination of hardware and software.

[0093] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for controlling azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning, characterized in that: Include: The azimuth beam start scanning angular velocity and the end scanning angular velocity are set according to the imaging scene and the azimuth geometric resolution, and the azimuth beam scanning angular acceleration is set based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change of the sliding beam mode; The beam scanning speed of the spaceborne SAR sliding spotlight mode is adjusted according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

2. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 1, characterized in that: Set the azimuth beam start scanning angular velocity and end scanning angular velocity, including: The azimuth resolution improvement factor corresponding to the starting azimuth resolution and the ending azimuth resolution is set according to the starting azimuth resolution, the ending azimuth resolution, the beam width, the wavelength and the azimuth pulse pressure broadening coefficient of the gradual imaging scene; Based on the azimuth resolution improvement factor and utilizing the relationship between the azimuth scanning angular velocity and the azimuth resolution, the azimuth starting beam scanning angular velocity and the ending scanning angular velocity are obtained.

3. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 1, characterized in that: Set the azimuth beam scanning angular acceleration, including: The azimuth beam moving speed in the corresponding sliding beam mode is obtained according to the azimuth beam starting scanning angular velocity and ending scanning angular velocity and the shortest slant distance from the imaging scene center to the satellite track; According to the azimuth beam start scanning angular velocity and end scanning angular velocity and the imaging mapping strip length, the time for the center of the radar beam footprint to pass through the entire mapping strip in azimuth is obtained; The azimuth beam scanning angular acceleration is obtained based on the time when the center of the radar beam footprint passes through the entire surveying strip in azimuth, the azimuth beam start scanning angular velocity, and the azimuth beam end scanning angular velocity.

4. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 1, characterized in that: Adjusting the beam scanning speed of the spaceborne SAR sliding spotlight mode according to the azimuth beam scanning angular acceleration includes: Set the initial scanning angular velocity and the final scanning angular velocity of the azimuth beam, and set the radar azimuth beam scanning duration and scanning start time according to the relative geometric relationship between the satellite and the imaging scene; Constructing the beam scanning angular velocity variation expression according to the azimuth beam initial scanning angular velocity and the terminal scanning angular velocity, the scanning duration and the scanning start time; The azimuth beam pointing at different azimuth times is obtained according to the beam scanning angular velocity variation expression, and the azimuth beam pointing is discretized; The number of radar dwell pulses for different azimuth beam orientations is set according to the discretized azimuth beam orientations.

5. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 4, characterized in that: Set the initial scanning angular velocity and the final scanning angular velocity of the azimuth beam, including: The synthetic aperture time is set according to the beam width of azimuth focused imaging, the speed of the spaceborne SAR beam footprint moving along the ground when no azimuth beam scanning is performed, the shortest slant distance from the center of the imaging scene to the satellite track, and the azimuth resolution improvement factor; The initial scanning angular velocity and the terminal scanning angular velocity of the azimuth beam are obtained according to the synthetic aperture time and the azimuth beam scanning angular velocity.

6. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 5, characterized in that: Set the radar azimuth beam scanning duration and scanning start time, including: Obtaining sliding spotlight mode radar imaging time according to synthetic aperture time; Calculate the start and end angles of the azimuth beam scan according to the initial scanning angular velocity and the end scanning angular velocity of the azimuth beam and the radar imaging time; The start and end angles of the azimuth beam scan are used to obtain the start time of the radar beam scan.

7. The method for controlling the azimuth beam scanning of a spaceborne sliding spotlight SAR based on uniformly variable speed scanning according to claim 5, characterized in that: Discretize the azimuth beam pointing, including: The azimuth beam pointing is discretized according to the beam jump of the antenna azimuth beam scanning, so as to calculate the number of radar dwell pulses of a single azimuth beam pointing according to the discretized azimuth beam pointing.

8. A spaceborne sliding spotlight SAR azimuth beam scanning control system based on uniformly variable speed scanning, characterized in that: It includes: a scanning angular acceleration setting module and an azimuth resolution imaging module, wherein: A scanning angular acceleration setting module is used to set the azimuth beam start scanning angular velocity and the end scanning angular velocity according to the imaging scene and the azimuth geometric resolution, and to set the azimuth beam scanning angular acceleration based on the azimuth beam start scanning angular velocity and the end scanning angular velocity and according to the imaging mapping strip length and azimuth resolution change in the sliding beam focusing mode; The azimuth resolution imaging module is used to adjust the beam scanning speed of the satellite-borne SAR sliding beam mode according to the azimuth beam scanning angular acceleration to achieve multi-azimuth resolution imaging of the imaging scene.

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