Calibration method and device for non-zero degree dihedral corner reflector

Abstract

The present invention provides a calibration method and device for a non-zero-degree dihedral corner reflector, the method comprising: calculating a theoretical attitude angle of the non-zero-degree dihedral corner reflector; measuring an inclination angle of a first boundary of the non-zero-degree dihedral corner reflector relative to a horizontal plane; calculating an actual attitude angle corresponding to a current state of the non-zero-degree dihedral corner reflector according to the inclination angle; measuring an angle between a horizontal projection of a second boundary of the non-zero-degree dihedral corner reflector and a flight path of a synthetic aperture radar; and calibrating the non-zero-degree dihedral corner reflector according to an error between the theoretical attitude angle and the actual attitude angle and the angle.

Description

Technical Field

[0001] The present disclosure relates to the field of radar technology, and in particular to a calibration method and device for a non-zero-degree dihedral reflector. Background Art

[0002] Synthetic aperture radar (SAR) earth observation has gradually moved from early qualitative analysis to quantitative application, and SAR calibration technology is the key. The full polarization SAR system measures the full polarization scattered echo in each resolution unit in the target scene to obtain its full polarization scattering characteristics, which can provide richer information than single-polarization SAR. However, the data obtained by the full polarization SAR system will be affected by system errors such as polarization crosstalk, polarization channel amplitude imbalance, and polarization channel phase imbalance. Only after calibration can quantitative data application be carried out.

[0003] At present, the common practice of calibrating SAR data is to obtain the polarization calibration parameters of the radar system by placing a group of corner reflectors for polarization calibration on the ground (usually including trihedral corner reflectors, zero-degree dihedral angle scatterers, 45-degree dihedral angle reflectors or 22.5-degree dihedral angle reflectors) to perform polarization calibration on the SAR image. Among them, the angle adjustment of trihedral corner reflectors and zero-degree dihedral angle reflectors is relatively easy, and the pitch angle and azimuth angle can be directly measured using a level and an address compass, while the attitude angle measurement of non-zero-degree dihedral angle reflectors (such as 45-degree dihedral angle reflectors, 22.5-degree dihedral angle reflectors, etc.) cannot be directly measured using existing equipment. Summary of the invention

[0004] In view of this, on the one hand, the present disclosure provides a calibration method for a non-zero degree dihedral corner reflector, comprising: calculating a theoretical attitude angle of the non-zero degree dihedral corner reflector; measuring an inclination angle of a first boundary of the non-zero degree dihedral corner reflector relative to a horizontal plane; calculating an actual attitude angle corresponding to a current state of the non-zero degree dihedral corner reflector according to the inclination angle; measuring an angle between a horizontal projection of a second boundary of the non-zero degree dihedral corner reflector and a flight path of a synthetic aperture radar; and calibrating the non-zero degree dihedral corner reflector according to an error between the theoretical attitude angle and the actual attitude angle and the angle.

[0005] According to an embodiment of the present disclosure, wherein the theoretical attitude angle includes a theoretical pitch angle, a theoretical rotation angle and a theoretical azimuth angle, the calculation of the theoretical attitude angle of the non-zero degree dihedral angle reflector includes: calculating the theoretical pitch angle according to the flight route of the synthetic aperture radar and the position of the non-zero degree dihedral angle reflector; determining the theoretical rotation angle according to the calibration requirements of the synthetic aperture radar; and calculating the theoretical azimuth angle according to the azimuth angle of the flight route, the theoretical pitch angle and the theoretical rotation angle.

[0006] According to an embodiment of the present disclosure, the step of calculating the theoretical azimuth angle according to the azimuth angle of the flight route, the theoretical pitch angle and the theoretical rotation angle comprises:

[0007] θ z =θ0±arctan(tanθ y sinθ x )

[0008] Calculate the theoretical azimuth angle θ z , where θ0 is the azimuth of the flight route, θ x is the theoretical pitch angle, θ y is the theoretical rotation angle.

[0009] According to an embodiment of the present disclosure, measuring the inclination angle of the first boundary of the non-zero degree dihedral corner reflector relative to the horizontal plane includes: measuring the inclination angle of the top edge or the bottom edge of the non-zero degree dihedral corner reflector relative to the horizontal plane with the horizontal plane as a reference.

[0010] According to an embodiment of the present disclosure, a level ruler or an inclinometer is used to measure the inclination angle of the top edge or the bottom edge of the non-zero-degree dihedral corner reflector relative to the horizontal plane.

[0011] According to an embodiment of the present disclosure, the actual attitude angle includes an actual pitch angle and an actual rotation angle, and the actual attitude angle corresponding to the current state of the non-zero-degree dihedral reflector is calculated according to the tilt angle.

[0012]

[0013] Calculate the actual pitch angle and the actual rotation angle Wherein, θ1 and θ2 are the bevel angles of the two boundaries of the non-zero-degree dihedral corner reflector, respectively.

[0014] According to an embodiment of the present disclosure, measuring the angle between the horizontal projection of the second boundary of the non-zero degree dihedral corner reflector and the flight path of the synthetic aperture radar includes: measuring the angle between the horizontal projection of the side of the non-zero degree dihedral corner reflector and the flight path of the synthetic aperture radar with the horizontal plane as a reference.

[0015] According to an embodiment of the present disclosure, the theoretical attitude angle includes a theoretical pitch angle, a theoretical rotation angle and a theoretical azimuth angle, and the actual attitude angle includes an actual pitch angle and an actual rotation angle; the calibrating the non-zero degree dihedral corner reflector according to the error between the theoretical attitude angle and the actual attitude angle and the included angle includes: calibrating the pitch angle and the rotation angle of the non-zero degree dihedral corner reflector according to a first error between the theoretical pitch angle and the actual pitch angle and a second error between the theoretical rotation angle and the actual rotation angle; calculating the current azimuth angle of the non-zero degree dihedral corner reflector according to the pitch angle, rotation angle and the included angle of the non-zero degree dihedral corner reflector after calibration; and calibrating the azimuth angle of the non-zero degree dihedral corner reflector according to a third error between the theoretical azimuth angle and the current azimuth angle.

[0016] According to an embodiment of the present disclosure, the calibrating the azimuth angle of the non-zero-degree dihedral corner reflector includes: rotating the non-zero-degree dihedral corner reflector as a whole with a direction perpendicular to a horizontal plane as a rotation axis to eliminate the third error.

[0017] On the other hand, the present disclosure provides a calibration device for a non-zero degree dihedral corner reflector, comprising: a first calculation module, used to calculate the theoretical attitude angle of the non-zero degree dihedral corner reflector; a first measurement module, used to measure the inclination angle of the first boundary of the non-zero degree dihedral corner reflector relative to the horizontal plane; a second calculation module, used to calculate the actual attitude angle corresponding to the current state of the non-zero degree dihedral corner reflector according to the inclination angle; a second measurement module, used to measure the angle between the horizontal projection of the second boundary of the non-zero degree dihedral corner reflector and the flight path of a synthetic aperture radar; and a calibration module, used to calibrate the non-zero degree dihedral corner reflector according to the error between the theoretical attitude angle and the actual attitude angle and the angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0019] Figure 1 A flow chart of a calibration method for a non-zero-degree dihedral corner reflector provided in an embodiment of the present disclosure is schematically shown.

[0020] Figure 2 The flowchart of the specific calibration process provided by the embodiment of the present disclosure is schematically shown.

[0021] Figure 3 A modeling diagram of a zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0022] Figure 4A modeling diagram of a non-zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0023] Figure 5 A top view of a non-zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0024] Figure 6 The polarization image of a 45-degree dihedral reflector obtained without using the calibration method provided in the embodiment of the present disclosure is schematically shown.

[0025] Figure 7 The polarization image of a 45-degree dihedral reflector obtained by the calibration method provided in an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0027] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0028] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0029] In the description of the present disclosure, it is necessary to understand that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0030] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the claims, any reference symbol between brackets shall not be construed as a limitation to the claims.

[0031] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0032] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] The purpose of the present disclosure is to solve the problem that the attitude angle of a non-zero-degree dihedral reflector cannot be directly measured. The present disclosure derives the attitude angle formula of a non-zero-degree dihedral reflector in detail. By measuring the tilt angle, various attitude angle parameters can be obtained in real time, thereby realizing the accurate measurement and adjustment of the attitude of the non-zero-degree dihedral reflector. At the same time, according to the relationship between the attitude angles of the non-zero-degree dihedral reflector, a complete attitude angle adjustment and measurement scheme for the non-zero-degree dihedral reflector is given, which has wide applicability.

[0034] Figure 1 A flow chart of a calibration method for a non-zero-degree dihedral corner reflector provided in an embodiment of the present disclosure is schematically shown.

[0035] like Figure 1 As shown, the method may include, for example, operations S101 to S104.

[0036] In operation S101 , a theoretical attitude angle of a non-zero-degree dihedral corner reflector is calculated.

[0037] In the disclosed embodiment, the theoretical attitude angle may include, for example, a theoretical pitch angle, a theoretical rotation angle, and a theoretical azimuth angle. The incident angle of the non-zero-degree dihedral reflector, that is, the theoretical pitch angle of the non-zero-degree dihedral reflector, may be calculated according to the position of the flight route of the synthetic aperture radar and the position of the non-zero-degree dihedral reflector. The theoretical rotation angle is determined according to the calibration requirements of the synthetic aperture radar. The theoretical azimuth angle is calculated according to the azimuth angle of the flight route, the theoretical pitch angle, and the theoretical rotation angle.

[0038] Specifically, according to

[0039] θ z =θ0±arctan(tanθ y sinθ x )

[0040] Calculate the theoretical azimuth angle θ z , where θ0 is the azimuth of the flight path, θ x is the theoretical pitch angle, θ y is the theoretical rotation angle.

[0041] In operation S102, a tilt angle of a first boundary of a non-zero degree dihedral corner reflector relative to a horizontal plane is measured.

[0042] In the embodiment of the present disclosure, the inclination angle of the top edge or the bottom edge of the non-zero-degree dihedral corner reflector relative to the horizontal plane can be measured with the horizontal plane as a reference. Exemplarily, a level ruler or an inclinometer is used to measure the inclination angle of the top edge or the bottom edge of the non-zero-degree dihedral corner reflector relative to the horizontal plane. For example, the first boundary may include two top edges or two bottom edges of the non-zero-degree dihedral corner reflector.

[0043] In operation S103, an actual attitude angle corresponding to the current state of the non-zero-degree dihedral corner reflector is calculated according to the tilt angle.

[0044] In the embodiment of the present disclosure, the actual attitude angle may include, for example, an actual pitch angle and an actual rotation angle.

[0045]

[0046] Calculate the actual pitch angle and the actual rotation angle Wherein, θ1 and θ2 are the inclination angles of the two first boundaries of the non-zero-degree dihedral corner reflector, respectively.

[0047] In operation S104 , an angle between a horizontal projection of a second boundary of the non-zero-degree dihedral corner reflector and a flight path of the synthetic aperture radar is measured.

[0048] In an embodiment of the present disclosure, the angle between the horizontal projection of the side of the non-zero-degree dihedral corner reflector and the flight path of the synthetic aperture radar may be measured with the horizontal plane as a reference.

[0049] In operation S105, the non-zero-degree dihedral corner reflector is calibrated according to the error between the theoretical attitude angle and the actual attitude angle and the included angle.

[0050] Figure 2 The flowchart of the specific calibration process provided by the embodiment of the present disclosure is schematically shown.

[0051] like Figure 2 As shown, in the embodiment of the present disclosure, first, the pitch angle and the rotation angle of the non-zero-degree dihedral reflector are calibrated, specifically, the pitch angle and the rotation angle of the non-zero-degree dihedral reflector are calibrated according to the first error between the theoretical pitch angle and the actual pitch angle and the second error between the theoretical rotation angle and the actual rotation angle. After each adjustment, the actual pitch angle and the actual rotation angle are calculated by continuing to measure the tilt angle, and then compared with the theoretical pitch angle and the theoretical rotation angle for adjustment, until the actual pitch angle and the actual rotation angle are consistent with the theoretical pitch angle and the theoretical rotation angle, then the pitch angle and the rotation angle calibration is completed.

[0052] Then, the current azimuth of the non-zero-degree dihedral reflector is calculated based on the pitch angle, rotation angle and included angle of the calibrated non-zero-degree dihedral reflector. The azimuth of the non-zero-degree dihedral reflector is calibrated based on the third error between the theoretical azimuth and the current azimuth. Similarly, after each adjustment, the current azimuth is calculated by continuing to measure the included angle, and then compared with the theoretical azimuth for adjustment until the current azimuth elevation and the theoretical azimuth match, and the azimuth calibration is completed. The non-zero-degree dihedral reflector can be rotated as a whole with the direction perpendicular to the horizontal plane as the rotation axis to eliminate the third error.

[0053] In order to further illustrate the principle of the calibration method provided by the embodiment of the present disclosure, the following is a Figure 3 -Attached Figure 7 The calibration method is further described.

[0054] Figure 3 A modeling diagram of a zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0055] A non-zero-degree dihedral reflector is formed by rotating a zero-degree dihedral reflector around the beam center at a certain angle. By modeling the zero-degree dihedral reflector, the initial position of the zero-degree dihedral reflector can be obtained.

[0056] like Figure 3As shown, the middle "crease" of the zero-degree dihedral reflector is defined as the x-axis, the horizontal direction (i.e. the direction of the beam center) is defined as the y-axis, the vertical direction is defined as the z-axis, and the origin of the coordinate is located at the midpoint of the "crease", i.e. the beam center. x Angle is defined as the pitch angle. Adjusting this angle can make the beam center of the dihedral reflector align with the height of the flight line; rotating around the y-axis θ y Angle is defined as the rotation angle. Adjusting this angle can make the zero-degree dihedral corner reflector become a specific angle dihedral corner reflector (collectively referred to as non-zero-degree dihedral corner reflector); rotate θ around the z-axis z The angle is defined as the azimuth angle. Adjusting this angle can make the dihedral reflector beam center perpendicular to the flight path. Comprehensive adjustment of the pitch angle θ x , rotation angle θ y 、Azimuth angle θ z , thereby completing the adjustment of the non-zero degree dihedral corner reflector.

[0057] set up Figure 3 The two faces of the 0-degree dihedral corner reflector shown are both squares with a side length of 2a, so the coordinates of the six points are:

[0058]

[0059] A non-zero-degree dihedral corner reflector is a zero-degree dihedral corner reflector rotated θ around the beam center. y Then adjust the pitch angle θ based on x and azimuth angle θ z , so that the beam center of the non-zero-degree dihedral corner reflector is completely facing the flight path.

[0060] Figure 4 A modeling diagram of a non-zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0061] like Figure 4 As shown, due to the azimuth angle θ z Adjustment can be done by rotating the dihedral reflector as a whole, which can be done independently, so it is not considered in this section for the time being.

[0062] Let the pitch angle θ x Taking the horizontal as the reference, upward is positive and downward is negative, then the rotation matrix is:

[0063]

[0064] Rotate the zero-degree dihedral reflector by θ y Angle, and then adjust the pitch angle θ x , we can get a non-zero dihedral corner reflector with a specific angle, and let the coordinates of the vertices of the rotated dihedral corner reflector be [X n Y n Zn ],but:

[0065] [X n Y n Z n ]=[XYZ]R y R x

[0066] After calculation, the coordinates of each point are:

[0067]

[0068] The coordinates of each point passing through the non-zero dihedral reflector [X n Y n Z n ] can be seen from the expression of x and the rotation angle θ y It is very difficult, so it is necessary to measure it indirectly and then calculate the pitch angle θ x and the rotation angle θ y The value of Figure 3 It can be seen that the inclination angles of the edges of the non-zero dihedral angles that are easiest to measure can be directly measured using a level or inclinometer. Therefore, the pitch angle θ can be calculated by inverse calculation using the inclination angles of the edges. x and the rotation angle θ y .

[0069] Let the top edge L 34 The inclination angle is θ 34 (corresponding to θ1 in the previous formula), according to the coordinate [X n Y n Z n ], we can get:

[0070]

[0071] Let the top edge L 45 The inclination angle is θ 45 (corresponding to θ2 in the previous formula), according to the coordinates [X n Y n Z n ], we can get:

[0072] Using the tilt angle θ 34 and the tilt angle θ 45 The expression of and rotation angle Right now:

[0073]

[0074] It can be seen that by directly measuring the edge L 34 The inclination angle is θ 34 and side L 45 The inclination angle is θ 45 , the actual pitch angle can be directly calculated and the actual rotation angle

[0075] Figure 5 A top view of a non-zero-degree dihedral corner reflector provided by an embodiment of the present disclosure is schematically shown.

[0076] Since the non-zero dihedral angle is to ensure that the beam center is facing the flight path, none of the edges coincide with the flight path. Figure 5 As shown, let the x-axis be the flight direction, and let the side L 23 The angle (acute angle) between the horizontal projection line of and the x-axis is δ 23 , according to the coordinates [X n Y n Z n ], we can get:

[0077]

[0078] Right now:

[0079] δ 32 =arctan(tanθ y sinθ x )

[0080] It can be seen that the side L 23 The horizontal projection line of 32 Angle, which is related to the pitch angle θ x and the rotation angle θ y Directly related.

[0081] Assume the azimuth of the flight path is θ0, and the side L 23 The azimuth angle is θ 32 ,but:

[0082] θ 32 =θ0±δ 32

[0083] Among them, δ 23 The positive and negative of the rotation angle θ y The positive and negative are the same.

[0084] Based on the above principle description, it can be seen that the calibration method for non-zero-degree dihedral reflectors provided by the embodiment of the present disclosure analyzes the relationship between the pitch angle, rotation angle, and azimuth angle of the non-zero-degree dihedral reflector by establishing a model, and obtains the expression of the attitude angle of the non-zero-degree dihedral reflector, and then the pitch angle and rotation angle can be obtained in real time through simple measurement to calibrate the non-zero-degree dihedral reflector. That is, the calibration process is simple and efficient with high calibration accuracy, which is conducive to real-time adjustment on site and has a wide range of applications.

[0085] In order to further verify the advantages of the calibration method provided by the embodiment of the present disclosure, specific experimental data are listed below for demonstration.

[0086] Figure 6 The polarization image of a 45-degree dihedral reflector obtained without using the calibration method provided in the embodiment of the present disclosure is schematically shown. Figure 7 The polarization image of a 45-degree dihedral reflector obtained by the calibration method provided in an embodiment of the present disclosure is schematically shown.

[0087] For example, taking the polarization calibration process in a certain flight experiment as an example, the ideal scattering matrix of a 45-degree dihedral reflector (a type of non-zero-degree dihedral reflector) is:

[0088]

[0089] Theoretically, the 45-degree dihedral reflector has the strongest signal energy on the cross-polarization image and the weakest signal energy on the co-polarization image.

[0090] When the non-zero-degree dihedral angle reflector adjustment and measurement scheme proposed in the present disclosure is not adopted, the image of the 45-degree angle reflector in each polarization channel is as follows: Figure 6 As shown in the figure, since the attitude angle has not been precisely measured and calculated, the signal energy on the cross-polarization image (the white dots in the rectangular box in the figure represent the signal energy) is not strong, which does not conform to the theoretical scattering matrix and is not conducive to the subsequent extraction of calibration parameters.

[0091] When the non-zero-degree dihedral angle reflector adjustment and measurement scheme proposed in the present disclosure is adopted, the image of the 45-degree angle reflector in each polarization channel is as follows: Figure 7 As shown in the figure, since each attitude angle is measured precisely and compared with the theoretical value, and fine-tuned repeatedly, the 45-degree dihedral reflector has the strongest signal energy on the cross-polarization image (the white dots in the rectangular box in the figure represent the signal energy), and the weakest signal energy on the co-polarization image, which is consistent with the theoretical scattering matrix and is conducive to the subsequent extraction of calibration parameters.

[0092] Based on the unified inventive concept, the disclosed embodiment also provides a calibration device for a non-zero-degree dihedral corner reflector, including: a first calculation module, used to calculate the theoretical attitude angle of the non-zero-degree dihedral corner reflector. A first measurement module, used to measure the inclination angle of the first boundary of the non-zero-degree dihedral corner reflector relative to the horizontal plane. A second calculation module, used to calculate the actual attitude angle corresponding to the current state of the non-zero-degree dihedral corner reflector according to the inclination angle. A second measurement module, used to measure the angle between the horizontal projection of the second boundary of the non-zero-degree dihedral corner reflector and the flight path of the synthetic aperture radar. A calibration module, used to calibrate the non-zero-degree dihedral corner reflector according to the error between the theoretical attitude angle and the actual attitude angle and the angle.

[0093] It should be noted that the device embodiment part corresponds to the invention embodiment part, and their implementation details and the effects brought about are also the same, which will not be repeated here.

[0094] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A calibration method for a non-zero-degree dihedral corner reflector, comprising: Calculating a theoretical attitude angle of the non-zero-degree dihedral corner reflector; measuring an inclination angle of a first boundary of the non-zero-degree dihedral corner reflector relative to a horizontal plane; Calculating an actual attitude angle corresponding to a current state of the non-zero-degree dihedral corner reflector according to the tilt angle; Measuring the angle between the horizontal projection of the second boundary of the non-zero degree dihedral corner reflector and the flight path of the synthetic aperture radar; Calibrate the non-zero-degree dihedral reflector according to the error between the theoretical attitude angle and the actual attitude angle and the included angle; Wherein, the theoretical attitude angle includes a theoretical pitch angle, a theoretical rotation angle and a theoretical azimuth angle; the actual attitude angle includes an actual pitch angle and an actual rotation angle; The calculating of the theoretical attitude angle of the non-zero-degree dihedral reflector comprises: calculating the theoretical pitch angle according to the position of the flight route of the synthetic aperture radar and the position of the non-zero-degree dihedral reflector; determining the theoretical rotation angle according to the calibration requirements of the synthetic aperture radar; calculating the theoretical azimuth angle according to the azimuth angle of the flight route, the theoretical pitch angle and the theoretical rotation angle; Calculating the actual attitude angle corresponding to the current state of the non-zero-degree dihedral reflector according to the tilt angle includes: according to Calculate the actual pitch angle and the actual rotation angle ,in, , are respectively the inclination angles of the two first boundaries of the non-zero-degree dihedral corner reflector; The calibrating the non-zero degree dihedral corner reflector according to the error between the theoretical attitude angle and the actual attitude angle and the included angle includes: calibrating the pitch angle and the rotation angle of the non-zero degree dihedral corner reflector according to a first error between the theoretical pitch angle and the actual pitch angle and a second error between the theoretical rotation angle and the actual rotation angle; calculating the current azimuth angle of the non-zero degree dihedral corner reflector according to the pitch angle, rotation angle and the included angle of the calibrated non-zero degree dihedral corner reflector; and calibrating the azimuth angle of the non-zero degree dihedral corner reflector according to a third error between the theoretical azimuth angle and the current azimuth angle.

2. The calibration method according to claim 1, wherein: The calculating the theoretical azimuth angle according to the azimuth angle of the flight route, the theoretical pitch angle and the theoretical rotation angle comprises: according to Calculate the theoretical azimuth ,in, is the azimuth of the flight route, is the theoretical pitch angle, is the theoretical rotation angle.

3. The calibration method according to claim 1, wherein: The measuring the inclination angle of the first boundary of the non-zero-degree dihedral corner reflector relative to the horizontal plane comprises: With the horizontal plane as a reference, the inclination angle of the top edge or the bottom edge of the non-zero-degree dihedral corner reflector relative to the horizontal plane is measured.

4. The calibration method according to claim 1 or 3, wherein: A level ruler or an inclinometer is used to measure the inclination angle of the top edge or the bottom edge of the non-zero-degree dihedral corner reflector relative to the horizontal plane.

5. The calibration method according to claim 1, wherein: Measuring the angle between the horizontal projection of the second boundary of the non-zero degree dihedral reflector and the flight path of the synthetic aperture radar comprises: With the horizontal plane as a reference, the angle between the horizontal projection of the side of the non-zero-degree dihedral corner reflector and the flight path of the synthetic aperture radar is measured.

6. The calibration method according to claim 1, wherein: The calibrating the azimuth angle of the non-zero-degree dihedral reflector comprises: The non-zero-degree dihedral corner reflector is rotated as a whole with a direction perpendicular to the horizontal plane as a rotation axis to eliminate the third error.

7. A calibration device for a non-zero-degree dihedral reflector, used to implement the calibration method according to any one of claims 1 to 6, comprising: A first calculation module, used for calculating the theoretical attitude angle of the non-zero-degree dihedral reflector; A first measuring module, used for measuring the inclination angle of the first boundary of the non-zero-degree dihedral corner reflector relative to the horizontal plane; A second calculation module, used for calculating an actual attitude angle corresponding to a current state of the non-zero-degree dihedral corner reflector according to the tilt angle; A second measurement module is used to measure the angle between the horizontal projection of the second boundary of the non-zero-degree dihedral reflector and the flight path of the synthetic aperture radar; A calibration module is used to calibrate the non-zero-degree dihedral reflector according to the error between the theoretical attitude angle and the actual attitude angle and the included angle.

Images