Realization method of spaceborne SAR sliding spotlight mode based on one-dimensional electric scanning of phased array antenna

Abstract

The application provides a kind of based on phased array antenna one-dimensional electric scanning satellite-borne SAR sliding bunch mode implementation method and system, comprising: by ground system to compile autonomous imaging schedule and to satellite;Load receives satellite's task instruction and carries out radar operating parameter calculation, and sends attitude parameter to attitude control subsystem;Attitude control subsystem is maneuvered to place according to the parameter provided by load before imaging;Load is driven by satellite attitude maneuver to complete target imaging by wave beam scanning;Satellite attitude yaw maneuver ± 90 °, load can also realize sliding aggregation imaging by SAR antenna azimuth wave beam electric scanning.The application adopts on-board radar parameter autonomous calculation mode, only needs to upload target position information, without ground system frequently instructs to arrange work.In addition, the phased array antenna is designed as one-dimensional electric scanning, reduces the number of component channels, reduces the weight and cost of the whole satellite, meets the use demand of user to lightweight, low-cost SAR satellite.

Description

Technical Field

[0001] This invention relates to the field of aerospace systems technology, and more specifically, to a method and system for realizing a spaceborne SAR sliding beam-gathering mode based on a one-dimensional electronically scanned phased array antenna. Background Technology

[0002] The sliding beam-spotting mode of spaceborne synthetic aperture radar controls the azimuth resolution by controlling the rotation speed of the antenna beam in the azimuth direction. Its imaging area is larger than that of spot-beam SAR, and its resolution can be higher than that of strip SAR with the same antenna size. It strikes a good balance between high resolution and large-area imaging. Currently, the main methods for implementing the sliding beam-spotting mode in orbit are planar phased array antennas and reflector antennas. Utilizing the two-dimensional electronic scanning capability of a planar phased array antenna to achieve beam scanning requires a large number of T / R components in the two-dimensional direction of the antenna. While this method is flexible, fast, and requires no attitude maneuvering, it is still effective.

[0003] However, these T / R components greatly increase the weight, power consumption and cost of the entire satellite, and increase the difficulty of engineering development. When using reflector antennas to achieve beams, it is necessary to rely on attitude two-dimensional maneuvering to drive the antenna beam scanning. However, for agile observation of multiple targets, the satellite attitude will frequently maneuver in the azimuth and range directions, which will reduce the efficiency of multi-target observation.

[0004] A search of existing technologies revealed the following:

[0005] In the research on on-orbit implementation methods of spaceborne SAR sliding beamforming mode, existing technologies employ two-dimensional maneuvering of the satellite platform to achieve satellite sliding beamforming imaging. For example, patent document CN103076607A discloses a method for achieving sliding beamforming mode based on SAR satellite attitude control; patent document CN106291557A discloses a satellite platform attitude maneuvering method for achieving ultra-high resolution sliding beamforming mode in spaceborne SAR; and patent document CN106226768A discloses a system parameter design method for ultra-high resolution agile SAR satellite sliding beamforming mode. However, when conducting emergency observations of multiple targets, these patent documents rely on frequent attitude maneuvers of the satellite platform in the azimuth and range directions, leading to a reduction in target observation efficiency.

[0006] In the prior art, patent document CN107505615A discloses a method for designing the attitude of a satellite in a spaceborne SAR sliding beam-focusing imaging mode. This method is designed for SAR satellites with parabolic antennas and uses three-axis attitude control of the satellite to complete the azimuth scanning of the radar beam. However, patent document CN107505615A limits the range observation swath because the range beam of the parabolic antenna cannot be widened.

[0007] Existing technology also includes patent document CN110034814A, which discloses a design method for agile satellite mission triggering mode commands. This method proposes an on-board autonomous mission planning method for the data transmission subsystem in mission triggering mode. However, patent document CN110034814A is not applicable to the autonomous calculation of on-board radar parameters in the sliding beam-focusing mode of the payload subsystem. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for implementing a sliding beam-gathering mode for spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna.

[0009] A method for implementing a sliding spotting mode for spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna, provided by the present invention, includes:

[0010] Step 1: The ground system compiles an autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite;

[0011] Step 2: The payload subsystem receives the mission command from the satellite, performs autonomous calculation of the on-board radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on.

[0012] Step 3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload, and ensures that the attitude maneuvers are in place before the payload is powered on;

[0013] Step 4: The payload completes the sliding convergence imaging of the target by performing radio wave scanning through satellite attitude maneuvers.

[0014] Preferably, it further includes:

[0015] Step 5: Set the imaging mode of the ground autonomous imaging plan to the azimuth electronic scanning sliding spotlight mode, and perform a satellite attitude yaw maneuver of ±90°.

[0016] Step 6: The ground system compiles an autonomous imaging plan for the sliding beam pattern and uploads it to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam imaging through azimuth beam electrical scanning of the SAR antenna.

[0017] Preferably, in step 1, after the satellite receives the autonomous imaging plan table from the ground, the satellite periodically polls the target position information in the plan table in real time based on the orbital recursion data. When the triggering condition is met, the satellite autonomously generates an imaging observation task.

[0018] Preferably, in step 2, the autonomous calculation of the onboard radar operating parameters comprehensively considers the influence of various factors such as orbital information, target information, earth model, SAR system constraints, and imaging performance, and selects a set of optimal parameters for imaging within a given range of conditions; at the same time, the payload subsystem feeds back the onboard calculated imaging start and end times, virtual point coordinates, azimuth scanning angle, and downward viewing angle attitude parameters to the attitude control subsystem via the bus.

[0019] Preferably, in step 3, after the attitude control system receives the attitude parameters provided by the payload, it ensures that the attitude maneuver is completed before the payload is powered on. The execution includes the following steps: 1) Under two-dimensional guidance attitude, the satellite maneuvers around the Xb axis of the body coordinate system to the lower view of the satellite; 2) Then, it performs attitude maneuver around the Yb axis so that the Zb axis points to the target virtual point; where the origin O refers to the satellite's center of mass, the Xb axis points to the direction of the satellite's flight, the Zb axis points to the direction of the Earth's center, and the Yb axis satisfies the right-hand rule.

[0020] Preferably, in step 4, under attitude coordination, the payload continuously rotates in the azimuth direction, driven by the satellite control platform, to drive the radio wave beam to complete the pointing and tracking of the target, without needing to consider the impact of the echo effect generated by the azimuth step scan on the imaging performance. This invention employs multiple control moment gyroscopes for roll-to-arbitrary-viewpoint maneuvers and pitch-to-attitude offsets, achieving high pointing accuracy, high stability, and rapid maneuvering for the satellite, meeting the payload's operational requirements.

[0021] Preferably, in step 5, the range direction and azimuth direction of the SAR antenna are interchanged, so that the azimuth direction of the SAR antenna has one-dimensional electronic scanning capability, and sliding convergence imaging is completed by the SAR antenna electronic beam scanning; the satellite achieves the switching of antenna polarization mode by attitude yaw maneuver ±90°.

[0022] Preferably, multi-angle imaging is achieved using forward and backward oblique looking sliding beam imaging modes. Under a specific field of view of the antenna, continuous observation of the target from multiple angles is achieved in the azimuth direction through satellite attitude maneuvers or SAR antenna radio beam scanning, thereby obtaining the target scattering characteristics at different azimuth angles. Considering the weight and volume limitations of lightweight satellites, the SAR planar phased array antenna is designed as a one-dimensional range-direction electronically scanned antenna. The azimuth beam of the SAR antenna is not scanned; instead, the SAR antenna radio beam scanning is driven by platform attitude maneuvers to achieve the azimuth beam oblique looking effect.

[0023] Preferably, in step 2, the following steps are taken: first, the downward viewing angle, slant range, and imaging start and end times required for imaging the target area are calculated based on the target location, current satellite location information, and extrapolated orbit information; then, the imaging parameters such as azimuth scanning angle, azimuth dwell pulse number, beam scan number, virtual point coordinates, pulse repetition frequency, pulse width, frame length, echo sampling start time, and echo delay pulse number are calculated based on the satellite platform, radar system, and imaging performance constraints.

[0024] According to the present invention, a system for realizing a sliding spotting mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna is provided, comprising:

[0025] Module M1: The ground system compiles the autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite;

[0026] Module M2: The payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on.

[0027] Module M3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on;

[0028] Module M4: The payload uses satellite attitude maneuvers to drive radio beam scanning to complete the sliding convergence imaging of the target.

[0029] Module M5: Set the ground autonomous imaging plan imaging mode to sliding spotlight mode (azimuth electronic scanning) and maneuver the satellite attitude yaw ±90°;

[0030] Module M6: The ground system compiles an autonomous imaging plan for the sliding beam pattern and uploads it to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before power-on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam imaging through azimuth beam electrical scanning of the SAR antenna.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. Compared with the traditional ground system command compilation method, the present invention only requires the ground to record information such as satellite target points, without the need for the ground system to perform complex tasks such as mission planning, parameter calculation and command compilation in advance according to user needs. The method of the present invention simplifies the satellite on-orbit use process and improves the efficiency of satellite on-orbit testing.

[0033] 2. This invention allows for flexible selection of the on-orbit implementation method of the sliding spotting mode based on user observation needs. Through satellite yaw ±90° attitude maneuvering, it can achieve sliding spotting imaging through both range-direction electronic scanning and azimuth-direction attitude maneuvering with the satellite, and range-direction electronic scanning and range-direction attitude maneuvering with the satellite. This invention fully leverages the payload electronic scanning capability of the SAR satellite and the platform's rapid maneuvering capability, ensuring high-efficiency and high-quality imaging.

[0034] 3. This invention designs the satellite planar phased array antenna as a one-dimensional electronically scanned antenna. On the one hand, the planar active phased array antenna has the ability to quickly, flexibly, and efficiently switch beam directions, ensuring the observation performance of the target. On the other hand, the design of the one-dimensional planar phased array antenna greatly reduces the weight, volume, and cost of the entire satellite, meeting the user's needs for lightweight and small SAR satellites. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 This is a schematic diagram of the process steps of the method of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the autonomous calculation process of on-board radar operating parameters according to an embodiment of the present invention.

[0038] Figure 3 The above is a sensitivity curve of the sliding beam convergence mode (azimuth attitude maneuver) system according to an embodiment of the present invention.

[0039] Figure 4 This is a sensitivity curve of the sliding beam-focusing mode (azimuth scanning) system in an embodiment of the present invention. Detailed Implementation

[0040] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0041] This invention discloses a method for implementing a sliding beamforming mode for spaceborne SAR based on a one-dimensional electronically scanned phased array antenna. The main steps are as follows: the ground system compiles an autonomous imaging plan and uploads it to the satellite; after receiving the mission instructions from the satellite, the payload calculates the radar operating parameters and sends the attitude parameters to the attitude control subsystem; the attitude control subsystem performs attitude maneuvers to the desired position before imaging according to the parameters provided by the payload; the payload completes target imaging by driving the radio beam scanning through satellite attitude maneuvers; by yaw maneuvering the satellite attitude ±90°, the payload can also achieve sliding beamforming imaging through azimuth beam scanning of the SAR antenna. This invention adopts an on-board radar parameter autonomous calculation method, requiring only the upload of target position information, eliminating the need for frequent instruction arrangement work by the ground system, thus simplifying the on-orbit use of the satellite. Furthermore, designing the phased array antenna as a one-dimensional electronically scanned antenna reduces the number of component channels, lowers the overall satellite weight and cost, and meets users' needs for lightweight, low-cost SAR satellites.

[0042] like Figure 1 As shown, the method for implementing a sliding spotting mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to the present invention mainly includes the following steps:

[0043] Step 1: The ground system compiles an autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite;

[0044] Step 2: The payload subsystem receives the mission command from the satellite, performs autonomous calculation of the on-board radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on.

[0045] Step 3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload, and ensures that the attitude maneuvers are in place before the payload is powered on;

[0046] Step 4: The payload completes the sliding convergence imaging of the target by performing radio wave scanning through satellite attitude maneuvers;

[0047] Step 5: Set the imaging mode of the ground autonomous imaging plan to sliding spotlight mode (azimuth electronic scanning), and maneuver the satellite attitude yaw ±90°;

[0048] Step 6: The ground system compiles an autonomous imaging plan for the sliding beam pattern and uploads it to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam imaging through azimuth beam electrical scanning of the SAR antenna.

[0049] In step 1, after the satellite receives the autonomous imaging plan from the ground, it periodically polls the target position information in the plan based on orbital recursion data in real time. When the triggering conditions are met, it autonomously generates an imaging observation task. This invention transfers radar operating parameters from ground-based calculation to on-board autonomous calculation, eliminating the need for ground systems to perform task planning and command arrangement in advance according to user needs, thus simplifying the on-orbit use of the satellite.

[0050] In step 2, the calculation of onboard radar operating parameters comprehensively considers the influence of various factors, including orbital information (satellite position and velocity), target information (target position and local elevation), Earth model (Earth rotation and Earth curvature), SAR system constraints (duty cycle and data rate), and imaging performance (ambiguity and NESZ). Within a given range of conditions, a set of optimal parameters is selected for imaging. Simultaneously, the payload subsystem feeds back the onboard calculated imaging start and end times, virtual point coordinates, azimuth scan angle, and downward viewing angle to the attitude control subsystem via a bus.

[0051] In step 3, after receiving the attitude parameters provided by the payload, the attitude control system ensures that the attitude maneuver is completed before the payload is powered on. The execution includes the following steps: 1) Under two-dimensional guided attitude, the satellite orbits the body coordinate system X. b 1) Rotate along the axis to the lower view of the satellite; 2) Rotate around the Y-axis again. b Axis attitude maneuver, enabling Z b The axis points to the target virtual point. The origin O points to the satellite's center of mass, and X... b The axis points in the direction of satellite flight, Z b The axis points to the Earth's center, Y b The axis satisfies the right-hand rule.

[0052] In step 4, with attitude coordination, the payload continuously rotates in the azimuth direction, driven by the satellite control platform, to drive the radio wave beam to complete the pointing and tracking of the target. There is no need to consider the impact of the echo effect generated by the azimuth step scan on imaging performance. This invention uses multiple control moment gyroscopes for roll-to-arbitrary-view maneuvers and pitch-to-attitude offsets, achieving high pointing accuracy, high stability, and rapid maneuvering for the satellite, meeting the payload's operational requirements.

[0053] In step 5, considering the user's urgent need for target observation, this invention urgently requires the satellite to possess rapid and efficient target observation capabilities. To fully leverage the advantages of planar active phased array antenna electrical scanning, this invention employs a ±90° yaw maneuver design, interchanges the range and azimuth directions of the SAR antenna, enabling the SAR antenna to have one-dimensional electrical scanning capability in the azimuth direction. This allows for sliding convergence imaging through SAR antenna electrical beam scanning, reducing satellite maneuver time and increasing target observation efficiency. Furthermore, the ±90° attitude yaw maneuver also allows for switching of antenna polarization modes, meeting the user's observation needs for different targets.

[0054] The present invention will be further described below.

[0055] This invention designs a sliding beamforming mode for spaceborne SAR using a one-dimensional electronically scanned phased array antenna. Based on this, multi-angle imaging can also be achieved using front-side and forward / backward oblique sliding beamforming modes. Within a specific antenna field of view, continuous observation of the target from multiple angles can be achieved through satellite attitude maneuvers or SAR antenna beam scanning in the azimuth direction, thereby acquiring the target scattering characteristics at different azimuth angles and enriching the target observation information. Considering the weight and volume limitations of lightweight satellites, this invention designs the SAR planar phased array antenna as a one-dimensional range-direction electronically scanned antenna. The azimuth beam of the SAR antenna is not scanned; instead, platform attitude maneuvers are used to drive the SAR antenna beam scanning, achieving an azimuth beam oblique-looking effect.

[0056] The present invention will now be described in more detail with reference to preferred embodiments.

[0057] Specifically, Table 1 is an autonomous imaging plan table for spaceborne SAR sliding spotting mode based on one-dimensional electronic scanning of phased array antennas provided in the embodiments of the present invention.

[0058] Table 1 Autonomous Imaging Plan

[0059] Parameter name length Signage W0 ID W1 Mission start time W2~W7 Mission End Time W8~W13 Imaging mode W14 Target location (X,Y,Z) W15~W23 Target area elevation W24~W25 Average scattering coefficient of target area W26~W27

[0060] For details, please see Figure 2 , Figure 2 This is a flowchart illustrating the autonomous calculation process of onboard radar operating parameters in a sliding beam-focusing mode for spaceborne SAR based on a one-dimensional electronically scanned phased array antenna, provided by an embodiment of the present invention. In step 2, the required downward viewing angle, slant range, and imaging start and end times for the target area are first calculated based on the target position, current satellite position information, and extrapolated orbit information. Then, based on the satellite platform, radar system, and imaging performance constraints, imaging parameters such as azimuth scanning angle, azimuth dwell pulse count, beam scan count, virtual point coordinates, pulse repetition frequency, pulse width, frame length, echo sampling start time, and echo delay pulse count are calculated. The main input and output parameters are described in the table below:

[0061] Table 2. Description of Input Parameters for Autonomous Calculation of On-board Radar Operating Parameters

[0062]

[0063]

[0064] Table 3. Explanation of Auto-Calculated Output Parameters of On-Satellite Radar Operating Parameters

[0065]

[0066] The effects of the present invention will be further explained below with reference to simulation data.

[0067] The simulation input parameters for this experiment are shown in Table 4. Based on the given input system requirements parameters, the main imaging indicators were simulated and calculated according to the method proposed in this invention. The results are shown in the appendix. Figure 3 and attached Figure 4 .

[0068] Table 4 Input parameters in the embodiments

[0069] Serial Number parameter Value 1. orbital altitude 500km 2. band X 3. Antenna system One-dimensional electrically scanned planar active phased array system 4. Speed ​​of light(m / s) <![CDATA[3.0×10 8 ]]> 5. Wavelength (m) 0.03125 6. Earth's radius (km) 6371.023 7. Work mode Sliding beam mode 8. Central perspective (°) 12 9. Resolution (m) 0.5 10. Range imaging bandwidth (km) 13 11. Azimuth imaging bandwidth (km) 10

[0070] Figure 3 , Figure 4 The sensitivity performance prediction results of the spaceborne SAR sliding spotting mode system using the planar phased array antenna range electronic scanning and azimuth satellite attitude maneuver, and the antenna azimuth electronic scanning and range attitude maneuver, respectively, are presented in the embodiments of the present invention. As shown in the figure, Figure 3The system sensitivity is better than 24.4 dB within the viewing angle range of 12–13.5°; Figure 4 The system sensitivity is better than 20.0 dB within the viewing angle range of 12–12.8°. Simulation analysis verifies the effectiveness of the proposed method for realizing the sliding beam-focusing mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna.

[0071] In summary, this invention utilizes the platform's rapid maneuverability and payload electronic scanning capabilities for integrated imaging design. Based on the user's observation requirements, the on-orbit implementation of the satellite sliding beamforming mode can be flexibly selected. It can achieve sliding beamforming imaging through both range-direction electronic scanning and azimuth-direction attitude maneuvering with the satellite, and range-direction electronic scanning and range-direction attitude maneuvering. Furthermore, this invention employs an autonomous calculation method for onboard radar operating parameters, requiring only ground-based input of target point information, eliminating the need for ground systems to pre-program mission planning and parameter calculations based on user needs. In addition, this invention designs the planar phased array antenna as a one-dimensional scanner. On one hand, the rapid, flexible, and efficient beam-pointing switching capability of the planar active phased array antenna ensures target observation performance; on the other hand, designing the planar phased array antenna as a one-dimensional electronic scanner significantly reduces the overall weight, volume, and cost of the satellite.

[0072] This invention also provides a system for realizing a sliding beamforming mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna. Those skilled in the art can implement the system by executing the steps of the method for realizing a sliding beamforming mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna. That is, the method for realizing a sliding beamforming mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna can be understood as a preferred embodiment of the system for realizing a sliding beamforming mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna. Specifically, according to the system for realizing a sliding beamforming mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna provided by this invention, it includes:

[0073] Module M1: The ground system compiles the autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite;

[0074] Module M2: The payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on.

[0075] Module M3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on;

[0076] Module M4: The payload performs target sliding convergence imaging by driving radio beam scanning through satellite attitude maneuvers;

[0077] Module M5: Set the ground autonomous imaging plan imaging mode to sliding spotlight mode (azimuth electronic scanning) and maneuver the satellite attitude yaw ±90°;

[0078] Module M6: The ground system compiles an autonomous imaging plan for the sliding beam pattern and uploads it to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before power-on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam imaging through azimuth beam electrical scanning of the SAR antenna.

[0079] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0080] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for implementing a sliding beam-gathering mode for spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna, characterized in that, include: Step 1: The ground system compiles an autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite; Step 2: The payload subsystem receives the mission command from the satellite, performs autonomous calculation of the on-board radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on. Step 3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload, and ensures that the attitude maneuvers are in place before the payload is powered on; Step 4: The payload completes the sliding convergence imaging of the target by performing radio wave scanning through satellite attitude maneuvers; Step 5: Set the imaging mode of the ground autonomous imaging plan to the azimuth electronic scanning sliding spotlight mode, and maneuver the satellite attitude yaw ±90°. Step 6: The ground system compiles an autonomous imaging plan for the sliding beam-focusing mode and uploads the plan to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before power-on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam-focusing imaging through azimuth beam electrical scanning of the SAR antenna; In step 5, the range and azimuth directions of the SAR antenna are interchanged, enabling the SAR antenna to have one-dimensional electronic scanning capability in the azimuth direction. Sliding convergence imaging is completed through SAR antenna electronic beam scanning. The satellite switches the antenna polarization mode by yaw maneuvering ±90°.

2. The method for realizing the sliding beam-gathering mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, In step 1, after the satellite receives the autonomous imaging plan table from the ground, the satellite periodically polls the target position information in the plan table in real time based on the orbital recursion data. When the triggering conditions are met, the satellite autonomously generates an imaging observation task.

3. The method for realizing the sliding beam-gathering mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, In step 2, the autonomous calculation of the onboard radar operating parameters comprehensively considers the influence of various factors such as orbital information, target information, earth model, SAR system constraints, and imaging performance, and selects a set of optimal parameters for imaging within the given conditions. At the same time, the payload subsystem feeds back the onboard calculated imaging start and end times, virtual point coordinates, azimuth scanning angle, and downward viewing angle attitude parameters to the attitude control subsystem via the bus.

4. The method for implementing spaceborne SAR sliding beam-gathering mode based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, In step 3, after receiving the attitude parameters provided by the payload, the attitude control system ensures that the attitude maneuver is completed before the payload is powered on. The execution includes the following steps: 1) Under two-dimensional guidance attitude, the satellite maneuvers around the Xb axis of the body coordinate system to the lower view of the satellite; 2) Then, it performs attitude maneuver around the Yb axis so that the Zb axis points to the target virtual point; where the origin O points to the center of mass of the satellite, the Xb axis points to the direction of the satellite's flight, the Zb axis points to the direction of the Earth's center, and the Yb axis satisfies the right-hand rule.

5. The method for realizing the sliding beam-gathering mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, In step 4, with attitude coordination, the payload continuously rotates in the azimuth direction using the satellite control platform to drive the radio wave beam to complete the pointing and tracking of the target, without having to consider the impact of the echo effect generated by the azimuth step scan on the imaging performance; the present invention uses multiple control moment gyroscopes to perform roll maneuvers at arbitrary viewing angles and pitch attitude offsets.

6. The method for implementing a sliding beam-gathering mode for spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, Multi-angle imaging is achieved by utilizing front-side and forward-slant sliding beam-focusing imaging modes. Under a specific field of view of the antenna, continuous observation of the target from multiple angles is achieved in the azimuth direction through satellite attitude maneuvering or SAR antenna radio wave beam scanning, thereby obtaining the target scattering characteristics at different azimuth angles. Considering the weight and volume limitations of small and lightweight satellites, the SAR planar phased array antenna is designed as a one-dimensional range-direction electronically scanned antenna. The azimuth beam of the SAR antenna is not scanned, and the SAR antenna radio wave beam scanning needs to be driven by the platform attitude maneuvering to achieve the azimuth beam slant-looking effect.

7. The method for realizing the sliding beam-gathering mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna according to claim 1, characterized in that, In step 2, the following steps are taken: First, based on the target location, current satellite location information, and extrapolated orbit information, the required downward viewing angle, slant range, and imaging start and end times for imaging the target area are calculated. Then, based on the satellite platform, radar system, and imaging performance constraints, the imaging parameters such as azimuth scanning angle, azimuth dwell pulse count, beam scan count, virtual point coordinates, pulse repetition frequency, pulse width, frame length, echo sampling start time, and echo delay pulse count are calculated.

8. A system for realizing a sliding beam-focusing mode of spaceborne SAR based on one-dimensional electronic scanning of a phased array antenna, characterized in that, include: Module M1: The ground system compiles the autonomous imaging plan for the sliding spotting mode and uploads the autonomous imaging plan to the satellite; Module M2: The payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before powering on. Module M3: The attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; Module M4: The payload performs target sliding convergence imaging by driving radio beam scanning through satellite attitude maneuvers; Module M5: Set the ground autonomous imaging plan imaging mode to the azimuth electronic scanning sliding spotlight mode, and maneuver the satellite attitude yaw ±90°; Module M6: The ground system compiles an autonomous imaging plan for the sliding beam-focusing mode and uploads it to the satellite; the payload subsystem receives the mission instructions from the satellite, autonomously calculates the onboard radar operating parameters, and sends the attitude parameters to the attitude control subsystem before power-on; the attitude control subsystem performs satellite attitude maneuvers according to the attitude parameters provided by the payload and ensures that the attitude maneuvers are in place before the payload is powered on; the payload achieves sliding beam-focusing imaging through azimuth beam scanning of the SAR antenna; In module M5, the range and azimuth directions of the SAR antenna are interchanged, enabling the SAR antenna to have one-dimensional electronic scanning capability in the azimuth direction. Sliding imaging is completed through SAR antenna electronic beam scanning. The satellite switches the antenna polarization mode by attitude yaw maneuvering ±90°.

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