Satellite-borne adjustable passive scaler and adjustable corner reflector

Abstract

The invention relates to an adjustable corner reflector which comprises three supporting rods which are arranged in an umbrella shape, and every two supporting rods are perpendicular to each other to form a supporting vertex part; and the three variable reflecting surfaces are arranged between every two of the three supporting rods. According to the invention, the change of the radar scattering sectional area of the corner reflector is changed by changing the unfolding and folding area of the reflecting surface of the triangular metal film, and the adjustable range of the RCS is 5-40dBsm, so that space-based radar radiometric calibration is realized; by adopting a folding and unfolding mechanism, the requirement of the satellite on the space is reduced; by adopting the adjustable corner reflector with the variable RCS, a plurality of RCS values can be obtained through equivalence, and the requirement for the number of satellites is reduced; the satellite-borne adjustable passive calibrator can make up for the airspace limitation of ground calibration, and realizes global calibration.

Description

Technical Field

[0001] The present invention relates to the field of radar technology in the electronic information industry, and in particular to a satellite-borne controllable passive calibrator and a controllable corner reflector. Background Art

[0002] In order to ensure the detection accuracy of space-based radar for earth observation, such as accurate quantitative remote sensing of the global carbon cycle, water cycle, sea surface waves, and land soil moisture, the radiation characteristics of the Tianji radar fluctuate due to changes in the space environment and device characteristics, resulting in limited quantitative remote sensing accuracy. It is urgent to carry out high-precision radiation calibration to improve the quantitative remote sensing accuracy of the Tianji radar.

[0003] At present, the high-precision radiation calibration of space-based radar is mainly achieved by laying out corner reflector arrays with different RCS values ​​on the ground. The radiation calibration accuracy can reach within 0.5dBsm, which can meet the quantitative remote sensing needs of space-based radar. However, due to the airspace restrictions of ground corner reflectors, it is difficult to support the quantitative remote sensing radiation calibration needs of space-based radars in polar regions, open seas and other regions. It is urgent to explore space-based radiation calibration technology.

[0004] Space-based radiometric calibration mainly relies on satellite platforms. To form space-based calibrators with different RCS values, multiple satellites need to form a formation, which results in high system cost and complex operation and control. Therefore, how to reduce the research cost and operation and control complexity of space-based calibrators is an urgent problem to be solved in the field of radar technology in the electronic information industry. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a satellite-borne adjustable passive calibrator and an adjustable corner reflector, which can reduce the satellite's demand for space by adopting a folding and unfolding mechanism; by adopting an adjustable metal film reflective surface, the RCS size of the corner reflector can be quickly changed to complete the space-based radar radiation calibration and reduce the number of corner reflectors. The satellite-borne adjustable passive calibrator can be used for a variety of satellite platforms such as micro-nano satellites, small satellites, medium and large satellites, laying the foundation for building a space-based calibration network.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides an adjustable corner reflector, comprising:

[0007] Three support rods, one end of which is hinged to the support apex; after the three support rods are unfolded, they are arranged perpendicular to each other in pairs, and a support surface installation position is formed between two adjacent support rods;

[0008] Three variable reflecting surfaces are respectively arranged in the supporting surface mounting positions.

[0009] According to a technical solution of the present invention, each of the variable reflecting surfaces comprises:

[0010] The metal film is in the shape of a right triangle, and the right-angle end of the metal film is fixedly connected to the supporting vertex portion;

[0011] A telescopic rod, the metal film is wound on the telescopic rod, a first reel and a second reel are respectively arranged at both ends of the telescopic rod, and each of the support rods is provided with a first reel track and a second reel track respectively matched with the first reel and the second reel; two right-angled sides of the metal film are respectively arranged in the first reel track and the second reel track;

[0012] The driving device includes an upper driving motor and a lower driving motor, which are respectively arranged at two ends of the support rod and are transmission-connected to the first reel, and are respectively used to drive the first reel to roll along the support rod toward the upper driving motor and the lower driving motor.

[0013] According to a technical solution of the present invention, the driving devices of the three variable reflecting surfaces operate synchronously, and the triangle formed by the hypotenuses of the three metal films is an equilateral triangle.

[0014] According to a technical solution of the present invention, each of the support rods is provided with a plurality of magnetic locking devices arranged at intervals.

[0015] According to a technical solution of the present invention, the number of the magnetic locking devices is N, the spacing is m, and the spacing of the magnetic locking devices satisfies:

[0016] m=(ac) / N

[0017] Wherein, a represents the length of the support rod; c represents the distance between the magnetic locking device at the support apex and the support apex;

[0018] The positional relationship between the RCS formed by the variable reflective surface and the nth magnetic locking device satisfies:

[0019]

[0020] Where λ represents the wavelength of the radar signal.

[0021] According to a technical solution of the present invention, the upper drive motor and the lower drive motor are also provided with an FPGA chip.

[0022] According to one aspect of the present invention, a space-borne adjustable passive calibrator is provided. According to a technical solution of the present invention, the space-borne adjustable passive calibrator comprises the above adjustable corner reflector, and further comprises:

[0023] An extension mechanism, one end of which is connected to the satellite platform;

[0024] A three-axis rotation servo module, arranged on an end of the extension mechanism away from the satellite platform;

[0025] The calibration control module is arranged on the satellite platform and is connected to the driving device of the variable reflecting surface through a power line.

[0026] According to a technical solution of the present invention, the extension mechanism module includes a first support structure, three second support structures and an unfolding mechanism, and the two ends of the unfolding mechanism are respectively connected to the first support structure and the satellite platform; the length of the second support structure is less than the length of the first support structure;

[0027] The three-axis rotation servo module includes a rotating platform and a three-axis servo module arranged on the top surface of the rotating platform, the bottom surface of the rotating platform is connected to the first supporting structure, and the three-axis servo module is connected to three second supporting structures; the three second supporting structures are respectively connected to three support rods.

[0028] According to a technical solution of the present invention, the calibration control module includes a three-axis rotation servo module control unit and a drive device control unit.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention proposes a satellite-borne adjustable passive calibrator and an adjustable corner reflector for space-based radar radiation calibration. The radar scattering cross-sectional area of ​​the corner reflector is changed by changing the expansion and contraction area of ​​the triangular metal film reflection surface. The RCS can be adjusted in the range of 5-40 dBsm to realize the space-based radar radiation calibration. By adopting a folding and unfolding mechanism, the space demand of the satellite is reduced. By adopting an adjustable corner reflector with variable RCS, multiple RCS values ​​can be equivalent to reduce the number of satellites required. The satellite-borne adjustable passive calibrator can make up for the airspace limitation of ground calibration and realize global calibration.

[0031] The present invention arranges magnetic locking devices at fixed intervals on the support rod, so that when the motor stops, the reflecting surface overcomes the inertial influence and is in a stationary and stable state. The error of the stopping position from the predetermined position is controlled within 1 to 3 mm, and the accuracy is better than 0.3 dBsm, thereby ensuring the accuracy and stability of the RCS change of the corner reflector. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A control flow chart of a satellite-borne controllable passive calibrator according to an embodiment of the present invention is schematically shown;

[0034] Figure 2 A schematic diagram schematically shows the structure of a satellite-borne controllable passive calibrator according to an embodiment of the present invention;

[0035] Figure 3 A schematic diagram schematically shows the deployment of an extension mechanism according to an embodiment of the present invention;

[0036] Figure 4 A schematic diagram schematically shows the structure of an adjustable corner reflector according to an embodiment of the present invention;

[0037] Figure 5 A schematic diagram schematically showing the position of a magnetic locking device according to an embodiment of the present invention;

[0038] Figure 6 A schematic diagram schematically shows the structure of a driving device according to an embodiment of the present invention;

[0039] Figure 7 A control flow chart of a calibration control module according to another embodiment of the present invention is schematically shown.

[0040] in, Figure 1-Figure 7 The corresponding relationship between the reference numerals and the component names is as follows:

[0041] 10. Two-stage extension mechanism; 20. Three-axis rotation servo module; 30. Adjustable corner reflector 40. Calibration control module;

[0042] 101. first supporting structure; 102. second supporting structure; 103. unfolding mechanism;

[0043] 301, support rod; 302, metal film; 303, reel; 304, telescopic rod; 305, magnetic locking device; 306, supporting apex portion; 307, driving device. DETAILED DESCRIPTION

[0044] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0045] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0046] like Figure 1 and Figure 2 As shown, the present invention provides a satellite-borne adjustable passive calibrator for space-based radar radiation calibration, including an adjustable corner reflector 30, an extension mechanism 10, a three-axis rotation servo module 20 and a calibration control module 40.

[0047] like Figure 4 As shown, the adjustable corner reflector 30 enables the adjustable passive calibrator to generate different RCS by changing the side length of the corner reflector, so as to perform space-based radar radiation calibration.

[0048] The adjustable corner reflector 30 includes three support rods 301 and three variable reflective surfaces. One end of the three support rods 301 is hinged to the support vertex portion 306. After the three support rods 301 are unfolded, they are arranged perpendicular to each other in pairs, and a support surface mounting position is formed between two adjacent support rods 301. The three variable reflective surfaces are respectively arranged in the support surface mounting positions. The three support rods 301 are carbon fiber rods.

[0049] Each variable reflective surface includes a metal film 302, a driving device 307 and a telescopic rod 304. The metal film 302 is in the shape of a right triangle, the right-angled end of the metal film 302 is fixedly connected to the supporting vertex 306, and the metal film 302 is wound on the telescopic rod 304. As the reflective surface of the triangular corner reflector, the metal film 302 has good scattering characteristics and ductility. The RCS of the adjustable corner reflector 30 can be changed by changing the unfolded area of ​​the metal film 302. Three telescopic rods 304 are respectively arranged between two adjacent support rods 301, and form a support frame with the support rods 301. The metal film 302 is supported and arranged on the periphery of the support frame, and the unfolded area of ​​the metal film 302 can be changed by changing the position of the telescopic rod 304 on the support rod 301.

[0050] The driving device 307 is an upper driving motor and a lower driving motor, which are respectively arranged at the two ends of the support rod 301, and are drivingly connected to the first reel, and are respectively used to drive the first reel to roll along the support rod 301 in the direction close to the upper driving motor and the lower driving motor, and the motor is drivingly connected to the first reel 303 through the transmission device, driving the first reel 303 to slide along the support rod 301. The transmission device can be a first transmission belt and a second transmission belt connected to the first reel 303, and the upper driving motor and the lower driving motor arranged at the two ends of the support rod 301 rotate in opposite directions.

[0051] The first and second reels are respectively arranged at both ends of the telescopic rod 304, and the first and second reel tracks respectively matched with the first and second reels are arranged on each support rod 301; the two right-angled sides of the metal film 302 are respectively arranged in the first and second reel tracks. The first reel and the second reel are respectively rotatably arranged in the first and second reel tracks, and the two right-angled reels of the metal film 302 are wound on the reels through the rotation of the first and second reels.

[0052] The motor drives the first reel 303 to rotate, so that the telescopic rod 304 moves along the length direction of the support rod 301. The telescopic rod 304 moves along the support rod 301 and rolls with the first reel 303, so that the metal film 302 is unfolded or rolled on the telescopic rod 304.

[0053] The hypotenuse of the reflective surface of the triangular metal film 302 is driven to slide up and down; the magnetic locking device 305 enables the reflective surface to overcome the inertial influence and be in a static and stable state when the motor stops, thereby ensuring the accuracy and stability of the RCS change of the corner reflector; the corner reflector support vertex 306 is used to fix the position of the support rod 301 when the support rod 301 is unfolded to a mutually perpendicular position.

[0054] The driving devices 307 of the three variable reflective surfaces operate synchronously, and the triangle formed by the hypotenuses of the three metal films 302 is an equilateral triangle, ensuring that the triangular reflective surfaces formed by the three metal films 302 are the same.

[0055] Several magnetic locking devices 305 are arranged at intervals on each support rod 301, which are used to fix the first reel 303 to a specific position of the telescopic rod 304 when the motor stops driving, so as to maintain the stability of the metal film 302; the use of magnetic locking can reduce the demand for mechanical locking components, thereby reducing the wear and maintenance requirements in long-term operation. The magnetic locking device 305 can make the reflective surface overcome the inertial influence and remain in a static and stable state when the first reel 303 stops, ensuring the accuracy and stability of the RCS change of the corner reflector.

[0056] like Figures 2 to 6As shown, one end of the extension mechanism 10 is connected to the satellite platform to fix and support the passive calibrator. The extension mechanism 10 adopts a two-stage structure, including a first support structure 101, three second support structures 102 and an unfolding mechanism 103. The first support structure 101 is used to connect to the satellite platform; the second support structure 102 is used to support the adjustable corner reflector 30; and the two ends of the unfolding mechanism 103 are respectively connected to the first support structure 101 and the satellite platform. The length of the second support structure 102 is less than the length of the first support structure 101.

[0057] The length of the first support structure 101 is L1, which is generally 2 to 6 meters, the length of the second support structure 102 is L2, and the length of the support rod 301 is a, L1>a+L2. The lengths of the first support structure 101, the second support structure 102 and the support rod 301 can be adjusted according to actual needs.

[0058] The three-axis rotation servo module 20 is used to adjust the normal direction of the corner reflector to point to the calibrated radar satellite. The three-axis rotation servo module 20 includes a rotating platform and a three-axis servo module arranged on the top surface of the rotating platform, the bottom surface of the rotating platform is connected to the first support structure 101, and the three-axis servo module is connected to three second support structures 102; the three second support structures 102 are respectively connected to three support rods 301.

[0059] The calibration control module 40 is used to control the expansion and contraction of the two-stage extension mechanism 10 and the corner reflector frame, the three-axis rotation servo module 20, and the control motor rotation, so as to control the change of the corner reflector reflection surface, so as to accurately control and adjust the RCS of the corner reflector. The calibration control module 40 includes a three-axis rotation servo module control unit and a drive device control unit, wherein the three-axis rotation servo module control unit is used to control the rotation of the three-axis rotation servo module; the drive device control unit is set on the satellite, and is connected to the drive device 307 through the power line and data line inside the two-stage extension mechanism 10, and is used to control the three-axis rotation servo module to adjust the normal line of the corner reflector to accurately align with the calibrated radar satellite, so as to improve the radiation calibration accuracy.

[0060] The magnetic locking devices 305 on the telescopic rod 304 are spaced at a distance of m, generally 0.1 to 0.5 meters, and the total number of magnetic devices is N. The spacing of the magnetic locking devices 305 satisfies:

[0061] m=(ac) / N

[0062] Wherein, a represents the length of the support rod 301; c represents the distance between the magnetic locking device 305 at the support vertex 306 and the support vertex 306, which is generally 0.2 to 0.5 meters;

[0063] The positional relationship between the RCS formed by the variable reflective surface and the nth magnetic locking device 305 satisfies:

[0064]

[0065] Where λ represents the wavelength of the radar signal.

[0066] Keeping a certain distance between the driving device 307 and the top angle of the reflector can reduce direct interference with the radar signal when the motor is running and ensure the purity of the signal; a certain distance helps to optimize the transmission efficiency of the torque, making the drive of the telescopic rod 304 more stable and effective.

[0067] The driving device 307 is also provided with an FPGA chip. The FPGA provides a high degree of flexibility, allowing the user to program and adjust the hardware logic as needed to adapt to different application scenarios.

[0068] The magnetic devices at different distances set RCS values ​​of different gears for the adjustable corner reflector 30. By generating different RCSs, the RCS and signal-to-noise ratio curves are fitted to calibrate the radar satellite to be calibrated.

[0069] For 1.26GHz radar signals, the RCS can be adjusted from 2 to 40dBsm, with an accuracy better than 0.1dBsm; for 3.2GHz radar signals, the RCS can be adjusted from 15 to 50dBsm, with an accuracy better than 0.2dBsm; for 5.4GHz radar signals, the RCS can be adjusted from 20 to 55dBsm, with an accuracy better than 0.2dBsm; for 9.6GHz radar signals, the RCS can be adjusted from 25 to 60dBsm, with an accuracy better than 0.3dBsm.

[0070] The relationship between the length a of the support rod 301, the wavelength λ of the radar signal, the distance d driven by the motor rotation and the RCS change of the corner reflector is as follows:

[0071]

[0072] like Figure 7 As shown, in the FPGA control process, it is necessary to first input the number of RCSs to be generated and each RCS value σ1, σ2, ..., σ R , and the wavelength λ of the radar signal. Calculate the side length d corresponding to the i-th RCS according to the following formula i :

[0073]

[0074] The radius of the motor wheel is r, and one rotation of the motor wheel corresponds to K pulses emitted by the FPGA. The relationship between the motor rotation distance d, the total number of pulses emitted by the FPGA, the number of motor rotations p, and the pulse number margin is as follows:

[0075] in

[0076] Through conditional judgment and loop function, d is calculated according to the formula i The corresponding p i and q i , until the motor slides to the specified position d i , generate an RCS. Repeat the above operation to generate R different RCS values. By generating different RCS, fit the RCS and signal-to-noise ratio curve to calibrate the radar satellite.

[0077] The present invention forms a passive calibrator with different RCS by adjusting the expansion and collection area of ​​the triangular metal film reflective surface. The RCS can be adjusted in the range of 5 to 40 dBsm, with an accuracy better than 0.3 dBsm, which can meet the radiation calibration of space-based radars with different wavelengths and different ranges. Compared with traditional corner reflectors, the satellite-borne adjustable passive calibrator provided by the present invention has variable RCS calibration capability and high RCS control accuracy.

[0078] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An adjustable corner reflector, characterized in that: include: Three support rods (301), one end of which is hinged to the support apex portion (306); after the three support rods (301) are unfolded, they are arranged perpendicular to each other in pairs, and a support surface installation position is formed between two adjacent support rods (301); Three variable reflecting surfaces are respectively arranged in the supporting surface mounting positions.

2. The adjustable corner reflector according to claim 1, characterized in that: Each of the variable reflecting surfaces comprises: The metal film (302) is in the shape of a right triangle, and the right-angle end of the metal film (302) is fixedly connected to the supporting vertex portion (306); A telescopic rod (304), the metal film (302) is wound on the telescopic rod (304), a first reel and a second reel are respectively arranged at both ends of the telescopic rod (304), and each of the support rods (301) is provided with a first reel track and a second reel track respectively matched with the first reel and the second reel; two right-angled sides of the metal film (302) are respectively arranged in the first reel track and the second reel track; The driving device (307) comprises an upper driving motor and a lower driving motor, wherein the upper driving motor and the lower driving motor are respectively arranged at two ends of the support rod (301), are drivingly connected to the first reel, and are respectively used to drive the first reel to roll along the support rod (301) in a direction close to the upper driving motor and the lower driving motor.

3. The adjustable corner reflector according to claim 2, characterized in that: The driving devices (307) of the three variable reflective surfaces operate synchronously, and the triangle formed by the hypotenuses of the three metal films (302) is an equilateral triangle.

4. The adjustable corner reflector according to claim 3, characterized in that: A plurality of magnetic locking devices (305) are arranged at intervals on each support rod (301).

5. The adjustable corner reflector according to claim 4, characterized in that: The number of the magnetic locking devices (305) is N, and the spacing is m. The spacing of the magnetic locking devices (305) satisfies: m=(ac) / N Wherein, a represents the length of the support rod (301); c represents the distance between the magnetic locking device (305) at the support apex (306) and the support apex (306); The positional relationship between the RCS formed by the variable reflection surface and the nth magnetic locking device (305) satisfies: Where λ represents the wavelength of the radar signal.

6. The adjustable corner reflector according to claim 2, characterized in that: The upper drive motor and the lower drive motor are provided with FPGA chips.

7. A satellite-borne controllable passive calibrator, characterized in that: The adjustable corner reflector according to any one of claims 1 to 6 further comprises: An extension mechanism (10), one end of which is connected to the satellite platform; A three-axis rotation servo module (20) is arranged on an end of the extension mechanism (10) away from the satellite platform; A calibration control module (40) is arranged on the satellite platform and connected to the driving device (307) of the variable reflection surface via a power line.

8. The satellite-borne controllable passive calibrator according to claim 7, characterized in that: The extension mechanism module comprises a first support structure (101), three second support structures (102) and an unfolding mechanism (103); two ends of the unfolding mechanism (103) are respectively connected to the first support structure (101) and the satellite platform; the length of the second support structure (102) is shorter than the length of the first support structure (101); The three-axis rotation servo module (20) comprises a rotation platform and a three-axis servo module arranged on the top surface of the rotation platform, the bottom surface of the rotation platform is connected to the first support structure (101), and the three-axis servo module is connected to three second support structures (102); The three second support structures (102) are respectively connected to the three support rods (301).

9. The satellite-borne controllable passive calibrator according to claim 7, characterized in that: The calibration control module (40) comprises a three-axis rotation servo module control unit and a drive device control unit.

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