Sar ground calibration corner reflector assisted emplacement apparatus and method

Abstract

The application provides a SAR ground calibration corner reflector auxiliary installation device and installation method, which comprises a mounting frame, an azimuth angle adjusting device, an elevation angle adjusting device and a reference assembly. The mounting frame is used for supporting on the ground. A triangular pyramid positioning body is connected with an elevation angle pointer of the elevation angle adjusting device through a telescopic connecting rod, and the azimuth angle adjusting device is used for adjusting the azimuth angle. The elevation angle adjusting device rotates synchronously with the azimuth angle pointer of the azimuth angle adjusting device, and the rotation plane of the elevation angle pointer is perpendicular to the azimuth angle pointer. When the azimuth angle and the elevation angle are adjusted to the position, the bottom edge of the reference surface of the triangular pyramid positioning body is parallel to the flight line, and the reference surface is coincided with a straight line which is perpendicular to the flight line and passes through the calibration point. At this time, the posture of the triangular pyramid positioning body is the same as that of the corner reflector. Since the triangular pyramid positioning body is similar to the corner reflector, the corner reflector only needs to be rotated to the position which is coincided with the triangular pyramid positioning body.

Description

Technical Field

[0001] This invention relates to the field of remote sensing technology, and in particular to an auxiliary installation device and method for SAR ground calibration angle reflectors. Background Technology

[0002] In microwave remote sensing ground calibration, determining the radar cross-section (RCS) of the ground target is crucial. In practice, corner reflectors are often used as ground calibration targets. Errors in the manufacturing of corner reflectors can cause RCS errors, while errors in position and orientation during installation can affect the microwave incident angle, causing it to deviate from the direction of maximum RCS, thus impacting calibration accuracy. Generally, once the corner reflector is finalized during ground calibration, its manufacturing errors cannot be changed. The only way to mitigate these effects and improve calibration accuracy is to ensure sufficiently precise position and orientation during installation.

[0003] During corner reflector installation, technicians first select a calibration field and calibration point based on the designed flight path and remote sensing imagery. Using the 3D information of the calibration point, flight altitude, and designed flight path, they calculate the azimuth and elevation angles of the corner reflector. For example, when the base of the corner reflector is triangular, the azimuth angle ensures that the base of the corner reflector, away from the calibration point, is parallel to the flight path. The elevation angle ensures that the straight line perpendicular to the designed flight path and passing through the calibration point is perpendicular to the opening of the corner reflector; the opening of the corner reflector is the surface with the largest radar cross-section.

[0004] To meet these two requirements, a level and a compass are typically used. A level measures the pitch angle of the corner reflector, while a compass, with its automatic north-pointing function, measures the azimuth angle. However, because the two instruments operate independently and the two measurement steps are performed separately, adjusting the first parameter often causes the first parameter to change again when adjusting the second, requiring multiple adjustments to barely meet the requirements. This installation method results in low installation accuracy, long time consumption, and severely impacts installation efficiency and quality. Summary of the Invention

[0005] This invention provides an auxiliary installation device and method for SAR ground calibration corner reflectors, addressing the shortcomings of existing technologies that use independent levels and compasses for corner reflector installation, where adjusting one parameter causes another to change, requiring repeated adjustments. This invention achieves the effect of providing references for both azimuth and elevation angles in a single SAR ground calibration corner reflector auxiliary installation device. Furthermore, through attitude transmission, it addresses the difficulty of installing large, heavy, and multi-shaped corner reflectors, transforming the cumbersome installation process of directly placing corner reflectors of different sizes into a rapid adjustment process using the device itself. This solves the practical difficulty of quickly and accurately installing corner reflectors of different specifications in the field.

[0006] This invention provides an auxiliary installation device for a SAR ground calibration angle reflector, comprising:

[0007] Mounting bracket, the bottom end of which is used for support on the ground;

[0008] An azimuth adjustment device is mounted on the mounting frame, and the azimuth adjustment device includes an azimuth pointer, which is rotatably connected to the mounting frame.

[0009] A pitch angle adjustment device is rotatably mounted on the mounting bracket, and the pitch angle adjustment device rotates synchronously with the azimuth pointer. The pitch angle adjustment device includes a pitch angle pointer, and the plane of rotation of the pitch angle pointer is perpendicular to the extension direction of the azimuth pointer.

[0010] The reference assembly includes a telescopic link and a triangular pyramid positioning body. One end of the telescopic link is connected to the proximal end of the pitch angle pointer, and the other end of the telescopic link extends along the axis of the pitch angle pointer in a direction away from the distal end of the pitch angle pointer. The reference surface of the triangular pyramid positioning body is connected to the end of the telescopic link away from the pitch angle pointer. The triangular pyramid positioning body is similar to a corner reflector. The axis of the telescopic link passes through the vertex of the triangular pyramid positioning body. The telescopic link is perpendicular to the reference surface, which is a plane opposite to the vertex of the triangular pyramid positioning body. The base of the reference surface is parallel to the azimuth pointer.

[0011] According to the SAR ground calibration angle reflector auxiliary placement device provided by the present invention, the azimuth adjustment device further includes:

[0012] The first dial is rotatably connected to the mounting bracket, and when the mounting bracket is supported on the ground, the first dial is parallel to the horizontal plane.

[0013] A compass, which is rotatably connected to the mounting bracket;

[0014] The rotation axes of the compass and the azimuth pointer are both collinear with the rotation axis of the first dial.

[0015] According to the SAR ground calibration angle reflector auxiliary placement device provided by the present invention, the compass is fixedly connected to the first scale, and the compass is located on the zero degree mark of the first scale.

[0016] According to the SAR ground calibration angle reflector auxiliary installation device provided by the present invention, the pitch angle adjustment device further includes a second scale, the second scale is rotatably connected to the mounting frame, and when the mounting frame is supported on the ground, the second scale is perpendicular to the horizontal plane;

[0017] The proximal end of the pitch angle pointer is rotatably connected to the center of the second dial, and the axis of rotation is perpendicular to the second dial.

[0018] According to the SAR ground calibration angle reflector auxiliary installation device provided by the present invention, the second scale is drivenly connected to the azimuth pointer, the second scale rotates synchronously with the azimuth pointer, and the plane on which the second scale is located is perpendicular to the direction of the azimuth pointer.

[0019] According to the SAR ground calibration angle reflector auxiliary mounting device provided by the present invention, the length of the mounting frame is adjustable.

[0020] According to the SAR ground calibration angle reflector auxiliary installation device provided by the present invention, damping elements are provided between the azimuth pointer, the first scale, the second scale and the elevation pointer and the mounting bracket.

[0021] According to the SAR ground calibration angle reflector auxiliary placement device provided by the present invention, a level is provided on the first dial and / or the second dial.

[0022] The present invention also provides a method for installing a SAR ground calibration corner reflector, wherein the corner reflector is installed using the SAR ground calibration corner reflector auxiliary installation device described above, the method comprising:

[0023] Acquire flight path information and calibration point information of the corner reflector. The flight path information includes the heading and altitude of the flight path, and the calibration point information includes the coordinates of the calibration point.

[0024] Based on the flight path information and the calibration point information of the corner reflector, the azimuth and pitch angles of the corner reflector are calculated. The azimuth angle is parallel to the flight path, and the pitch angle is equal to the angle between the straight line perpendicular to the flight path and passing through the calibration point and the horizontal line.

[0025] Support the bottom of the mounting bracket on the ground so that the azimuth pointer of the azimuth adjustment device is parallel to the horizontal plane;

[0026] Adjust the azimuth pointer so that the angle corresponding to the scale indicated by the azimuth pointer is equal to the azimuth angle;

[0027] Adjust the pitch angle pointer so that the angle corresponding to the scale indicated by the pitch angle pointer is equal to the pitch angle;

[0028] Adjust the reference component so that the vertex of the triangular pyramid positioning body is located at the calibration point;

[0029] Install the corner reflector such that its vertex is located at the calibration point, and that the outer surface of the triangular pyramid positioning body is in contact with the inner surface of the corner reflector.

[0030] According to the SAR ground calibration corner reflector placement method provided by the present invention, the installation of the corner reflector includes:

[0031] Shorten the length of the telescopic rod of the reference component, so that the triangular cone positioning body moves to above the ground;

[0032] Place the corner reflector on the ground, ensuring that the vertex of the corner reflector coincides with the calibration point;

[0033] Extend the telescopic rod, and adjust the angle of the corner reflector during the extension process. When the vertex of the triangular pyramid positioning body contacts the vertex of the inner side of the corner reflector, the side of the triangular pyramid positioning body fits into the side of the corner reflector.

[0034] The SAR ground calibration angle reflector auxiliary mounting device provided by this invention is fixed to the ground by a mounting bracket. The azimuth pointer is then rotated until the angle corresponding to the scale indicated by the azimuth pointer is equal to the azimuth angle. At this point, the azimuth pointer is parallel to the flight path. During the rotation of the azimuth pointer, the pitch adjustment device rotates synchronously with the azimuth pointer, and the rotation plane of the pitch angle pointer of the pitch adjustment device is perpendicular to the extension direction of the azimuth pointer, i.e., the rotation plane of the pitch angle pointer is perpendicular to the flight path. Then, the pitch angle pointer is rotated until the angle corresponding to the scale indicated by the pitch angle pointer is equal to the pitch angle, which is the angle between the straight line perpendicular to the flight path and passing through the calibration point of the angle reflector and the horizontal plane. At this point, the extension direction of the pitch angle pointer is parallel to the straight line perpendicular to the flight path and passing through the calibration point of the angle reflector. The height of the SAR ground calibration angle reflector auxiliary mounting device is adjusted so that the extension line of the axis of the telescopic rod of the reference component passes through the calibration point of the angle reflector. At this point, the extension direction of the pitch angle pointer is perpendicular to the flight path and passes through the calibration point of the angle reflector. Since the axis of the telescopic rod passes through the vertex of the triangular pyramid positioning body and is perpendicular to the reference plane of the triangular pyramid positioning body (the reference plane being the plane opposite the vertex of the triangular pyramid positioning body), and the triangular pyramid positioning body is similar to a corner reflector, the attitude of the triangular pyramid positioning body is the same as the attitude of the corner reflector once the azimuth and elevation angles are adjusted. The vertex of the corner reflector is placed at the calibration point, and then the telescopic rod is extended. During the extension, the angle of the corner reflector is rotated. When the vertex of the triangular pyramid positioning body intersects with the inner vertex of the corner reflector, the side surface of the triangular pyramid positioning body intersects with the side surface of the corner reflector, thus transferring the attitude of the triangular pyramid positioning body to the corner reflector. The attitude of the corner reflector at this point is the final attitude. The SAR ground calibration corner reflector auxiliary placement device provided by this invention can simultaneously complete the transfer of azimuth and elevation angles, avoiding the problem of the first parameter changing when adjusting the second parameter after adjusting the first parameter. By using the attitude transmission of this device, the original cumbersome installation operation of corner reflectors of different sizes is transformed into a rapid adjustment operation of this device, solving the practical difficulty of quickly and accurately installing corner reflectors of different specifications in the field.

[0035] Furthermore, in the SAR ground calibration angle reflector placement method provided by the present invention, since the SAR ground calibration angle reflector auxiliary placement device described above is used to place the angle reflector, it has the same advantages as described above. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a front view of the SAR ground calibration angle reflector auxiliary installation device provided by the present invention;

[0038] Figure 2 This is a side view of the SAR ground calibration angle reflector auxiliary installation device provided by the present invention;

[0039] Figure 3 This is a top view of the first dial provided by the present invention;

[0040] Figure 4 This is a schematic diagram of the structure of the triangular pyramid positioning body provided by the present invention;

[0041] Figure label:

[0042] 100. Longitudinal connecting rod; 210. First dial; 220. Compass; 230. Azimuth pointer; 310. Second dial; 320. Pitch pointer; 410. Telescopic connecting rod; 420. Triangular pyramid positioning body; 500. Level. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] After years of development, remote sensing has evolved from qualitative to quantitative remote sensing. Calibration is the prerequisite and foundation for conducting quantitative remote sensing. In microwave remote sensing, calibration work can be broadly divided into two categories: radiometric calibration and polarimetric calibration. Calibration is an indispensable step in achieving quantitative Earth observations via microwave remote sensing. Calibration is typically divided into point target calibration and area target calibration. Point targets refer to small ground features, such as small cars or metal signs, while area targets are targets with a certain distribution area and stable scattering, such as large, untouched, flat desert surfaces. Because finding ideal area targets is difficult, microwave remote sensing ground calibration generally uses point targets.

[0045] Taking microwave remote sensing radiometric calibration as an example, microwave remote sensing radiometric calibration is the process of calibrating the ability of a microwave remote sensing system to measure the amplitude and phase of the backscattered signal of a target and establishing the correspondence between them. That is, constructing an accurate relationship between the backscattering coefficient of the image and the ground object, it is a prerequisite for the quantitative application of microwave remote sensing, and its calibration accuracy directly affects the scope of subsequent data use.

[0046] Ground calibration of point targets in microwave remote sensing is generally accomplished using corner reflectors. Corner reflectors have a relatively stable and large radar cross-section and exhibit a 3dB beamwidth independent of wavelength and size. Therefore, corner reflectors have become a commonly used calibration device in microwave remote sensing radiometric calibration.

[0047] In microwave remote sensing ground calibration, determining the radar cross-section (RCS) of the corner reflector is crucial. Errors in the manufacturing of the corner reflector will cause RCS errors, while errors in position and orientation during installation will affect the microwave incident angle, causing it to deviate from the direction of maximum RCS, thus affecting the calibration results. Generally, in ground calibration, once the corner reflector is finalized, its manufacturing errors cannot be changed. The only way to reduce the impact and improve calibration accuracy is to ensure sufficiently precise position and orientation during installation.

[0048] To minimize the impact of installation on calibration accuracy, the following principles should generally be followed when installing corner reflectors:

[0049] First, make the azimuth reference line of the corner reflector parallel to the design flight path of the aircraft. Taking a triangular cone corner reflector as an example, the edge line of the base plate on the opening side is the azimuth reference line.

[0050] Second, adjust the elevation angle of the corner reflector according to the incident angle of the radar wave so that the normal direction of the corner reflector is parallel to the incident direction of the radar wave, that is, the incident direction of the radar wave is perpendicular to the opening surface of the corner reflector.

[0051] Third, ensure that the base of the corner reflector (if any) is not visible and that the base portion cannot receive radar waves.

[0052] Fourth, corner reflectors should be placed in areas with weak background reflectivity to facilitate the extraction of their location from microwave remote sensing images.

[0053] Fifth, corner reflectors should be installed as far away as possible from objects that are prone to multipath effects.

[0054] The general installation process for a corner reflector is as follows: After receiving the designed flight path, technicians, in conjunction with remote sensing imagery, select a calibration field and choose calibration points. Based on the three-dimensional information of the calibration points, flight altitude, and designed flight path, they calculate the azimuth and elevation angles of the corner reflector. The azimuth angle ensures that the bottom edge of the corner reflector's base plate on the open side is parallel to the designed flight path. The elevation angle ensures that a straight line perpendicular to the designed flight path and passing through the calibration points is perpendicular to the plane on the open side of the corner reflector. To achieve these two requirements, a level and a compass are typically used. The level measures the elevation angle of the corner reflector, and the compass has an automatic north-pointing function and can measure the azimuth angle of the bottom edge of the corner reflector.

[0055] Corner reflectors come in various specifications, such as trihedral and dihedral, and vary in size from 0.3 meters to 1.4 meters. They are also available with or without bases, and their weight varies considerably, with some weighing over 100 kilograms. Traditionally, corner reflectors are installed by directly using relevant instruments to adjust their azimuth and elevation angles according to the design parameters, making the installation process difficult.

[0056] Specifically, each installation involves first adjusting the azimuth using a compass, then adjusting the elevation using a level, and finally fixing both positions. Because the two instruments are independent and the two steps are separate, adjusting one parameter often results in the other changing, requiring multiple repetitions to barely meet the requirements, and necessitating at least two people to complete the task. This leads to two problems: low accuracy and low time and efficiency. During deployment, situations often arise where the design does not meet the third, fourth, or fifth requirements, necessitating temporary relocation of the placement location and significantly increasing the workload. Considering the safety of corner reflectors, there are also situations where corner reflectors are temporarily installed during testing, posing new challenges to installation efficiency and time, often requiring increased manpower or sacrificing the installers' rest time. In these cases, the aforementioned two problems become even more pronounced.

[0057] This invention provides an auxiliary installation device and method for SAR ground calibration corner reflectors. Addressing the shortcomings of existing technologies that use separate levels and compasses for corner reflector installation, where adjusting one parameter leads to changes in another, requiring repeated adjustments, this invention provides a single auxiliary installation device that simultaneously provides references for both azimuth and elevation angles. Furthermore, through attitude transmission, this device overcomes the difficulties of installing large, heavy, and multi-shaped corner reflectors, transforming the cumbersome installation process of directly placing corner reflectors of different sizes into a rapid adjustment process using the device itself. This solves the practical difficulty of quickly and accurately installing corner reflectors of different specifications (size, weight, and shape) in the field.

[0058] The following is combined with Figures 1 to 4 The present invention describes the SAR ground calibration angle reflector auxiliary installation device and installation method.

[0059] An embodiment of the present invention provides an auxiliary mounting device for a SAR ground calibration angle reflector, including a mounting frame, an azimuth adjustment device, an elevation adjustment device, and a reference component.

[0060] The mounting frame can be a longitudinal connecting rod 100, and the azimuth adjustment device and the pitch adjustment device can be set at different height positions along the length of the mounting frame. The longitudinal connecting rod 100 can be a telescopic rod, and the extension and retraction of the longitudinal connecting rod 100 can adjust the ground height of the azimuth adjustment device and the pitch adjustment device.

[0061] In one embodiment of the present invention, the longitudinal connecting rod 100 can be a hollow metal rod with an outer diameter of 1 cm. The longitudinal connecting rod 100 can be a three-section telescopic structure, with a length of 1 m when retracted and a length of 1.8 m when fully extended. The bottom end of the longitudinal connecting rod 100 can be a pointed tip, which facilitates the insertion and fixing of the bottom end of the longitudinal connecting rod 100 into the ground.

[0062] The azimuth adjustment device includes a first dial 210, a north compass 220, and an azimuth pointer 230.

[0063] The first dial 210 is rotatably connected to the mounting bracket, and when the mounting bracket is supported on the ground, the first dial 210 is parallel to the horizontal plane.

[0064] In one embodiment of the present invention, the first dial 210 can be a disc, and its upper surface has angular markings from 0 to 360 degrees. When the mounting bracket is a longitudinal connecting rod 100, the longitudinal connecting rod 100 passes through the center of the first dial 210, and the longitudinal connecting rod 100 and the first dial 210 are coaxially arranged. To prevent the first dial 210 and the longitudinal connecting rod 100 from rotating arbitrarily, a damping element can be provided between the first dial 210 and the longitudinal connecting rod 100. Under manual rotation, the first dial 210 can rotate around the longitudinal connecting rod 100, and when no external force is applied, the first dial 210 and the longitudinal connecting rod 100 remain relatively stationary.

[0065] The compass 220 is rotatably connected to the longitudinal connecting rod 100. To allow the compass 220 and the longitudinal connecting rod 100 to rotate freely, a bearing can be installed between the compass 220 and the longitudinal connecting rod 100. The purpose of the first dial 210 being rotatably connected to the mounting bracket is that after the compass 220 stops rotating, the first dial 210 can be rotated to a position where the 0-degree mark coincides with the compass 220, thus making reading more convenient.

[0066] One end of the azimuth pointer 230 is rotatably connected to the mounting bracket, and the other end extends radially along the longitudinal connecting rod 100. Since the first dial 210 can be rotated to a position where the 0-degree mark coincides with the compass 220, the angle value corresponding to the angle mark pointed to by the azimuth pointer 230 is the azimuth angle.

[0067] In addition, to prevent the azimuth pointer 230 from rotating arbitrarily, a damping element can be installed between the azimuth pointer 230 and the longitudinal connecting rod 100. When the azimuth pointer 230 is moved, the azimuth pointer 230 can rotate around the longitudinal connecting rod 100. When there is no external force interference, the azimuth pointer 230 remains stationary.

[0068] In some embodiments of the present invention, the compass 220 may also be fixedly connected to the first dial 210, and the zero mark of the compass 220 coincides with that of the first dial 210. When the compass 220 rotates to automatically point north, it drives the first dial 210 to rotate synchronously, ensuring that the zero mark of the first dial 210 always coincides with that of the compass 220.

[0069] The pitch angle adjustment device includes a second dial 310 and a pitch angle pointer 320.

[0070] The second dial 310 can be a disc. The second dial 310 is rotatably connected to the mounting bracket, and the axis of rotation is parallel to the radial direction of the second dial 310 and parallel to the axial direction of the mounting bracket. When the mounting bracket is supported on the ground, the second dial 310 is perpendicular to the horizontal plane, and at this time the axis of rotation is in the vertical direction.

[0071] The surface of the second dial 310 has angle markings, including a 0-degree marking, which can extend horizontally, that is, the 0-degree marking is perpendicular to the longitudinal connecting rod 100, and includes 0 to 180-degree markings and 0 to -180-degree markings in the clockwise and counterclockwise directions, respectively.

[0072] The proximal end of the pitch angle pointer 320 and the center of the second dial 310 can be connected by a rotating shaft, and the value of the angle scale pointed to by the pitch angle pointer 320 is the current pitch angle.

[0073] The second dial 310 and the azimuth pointer 230 can be connected by a fixed rod. When the azimuth pointer 230 rotates around the longitudinal connecting rod 100, the second dial 310 and the azimuth pointer 230 rotate synchronously. During the rotation, the plane on which the second dial 310 is located remains perpendicular to the azimuth pointer 230.

[0074] Since the second dial 310 can be linked with the azimuth pointer 230, when the azimuth pointer 230 is adjusted to a position parallel to the flight path, the second dial 310 also rotates synchronously with the azimuth pointer 230 until the pitch pointer 320 rotates in a plane perpendicular to the flight path. When the pitch pointer 320 rotates to the pitch angle, it is parallel to a straight line perpendicular to the flight path and passing through the calibration point. Then, by adjusting the height of the pitch angle adjustment device, the straight line containing the pitch pointer 320 passes through the calibration point. At this point, the straight line containing the pitch pointer 320 is collinear with the straight line perpendicular to the flight path and passing through the calibration point.

[0075] If the azimuth pointer 230 and the second dial 310 are not linked, after adjusting one pointer, it is necessary to return to confirm whether the other pointer is still in the correct position. In this invention, the second dial 310 and the azimuth pointer 230 are linked, which improves the efficiency and work effect of the entire installation process.

[0076] To prevent the pitch angle pointer 320 from rotating freely, a damping element can be installed between the rotating shaft and the second scale 310. When the pitch angle pointer 320 is manually rotated, the pitch angle pointer 320 can rotate. When the external force is lost, the pitch angle pointer 320 remains stationary relative to the second scale 310.

[0077] The reference components include a telescopic link 410 and a triangular cone positioning body 420.

[0078] One end of the telescopic link 410 is connected to the proximal end of the pitch angle pointer 320, and the telescopic link 410 extends along the axis of the pitch angle pointer 320 in a direction away from the distal end of the pitch angle pointer 320. After connection, the telescopic link 410 and the pitch angle pointer 320 are on the same straight line.

[0079] The triangular pyramid positioning body 420 is similar to a corner reflector; in this sense, it is a scaled-down version of the corner reflector. The reference plane of the triangular pyramid positioning body 420 is connected to the end of the telescopic link 410 furthest from the pitch angle pointer 320. The axis of the telescopic link 410 is perpendicular to the reference plane, and the extension of the axis of the telescopic link 410 passes through the vertex of the triangular pyramid positioning body 420. The base of the reference plane is parallel to the azimuth pointer 230.

[0080] It should be noted that the reference plane is the plane opposite the vertex of the triangular pyramid positioning body 420.

[0081] In one embodiment of the present invention, in order to ensure that the first dial 210 is parallel to the horizontal plane when the mounting bracket is supported on the ground, a level 500 can be set on the first dial 210. The level 500 can be a universal bubble level. When the bubble is in the center, it indicates that the first dial 210 is parallel to the horizontal plane.

[0082] Of course, the level 500 can also be set on the second dial 310. When the second dial 310 is in a vertical state, the first dial 210 is also in a state parallel to the horizontal plane.

[0083] Embodiments of the present invention also provide a method for placing a corner reflector, comprising the following steps:

[0084] Step S100: Obtain flight path information and calibration point information of the corner reflector. The flight path information includes the heading and altitude of the flight path, and the calibration point information includes the coordinates of the calibration point.

[0085] Step S200: Based on the flight route information and the calibration point information of the corner reflector, calculate the azimuth angle and pitch angle of the corner reflector. The azimuth angle is parallel to the flight direction, and the pitch angle is equal to the angle between the horizontal line and the straight line perpendicular to the flight route and passing through the calibration point.

[0086] Step S300: Support the bottom of the mounting bracket on the ground so that the azimuth pointer 230 of the azimuth adjustment device is parallel to the horizontal plane;

[0087] Step S400: Adjust the azimuth pointer 230 so that the scale indicated by the azimuth pointer 230 is equal to the azimuth angle;

[0088] Step S500: Adjust the pitch angle pointer 320 so that the scale indicated by the pitch angle pointer 320 is equal to the pitch angle;

[0089] Step S600: Adjust the reference component so that the vertex of the triangular pyramid positioning body 420 is located at the calibration point;

[0090] Step S700: Install the corner reflector, so that the vertex of the corner reflector is located at the calibration point, and make the outer surface of the triangular pyramid positioning body 420 fit against the inner surface of the corner reflector.

[0091] Specifically, when installing a corner reflector, it is first necessary to obtain the navigation information and the calibration point of the corner reflector.

[0092] The route information includes the heading and altitude of the route, and the calibration point is the position where the vertex of the corner reflector needs to be placed. The calibration point information includes the coordinates of the calibration point.

[0093] Based on the flight path information and the calibration point of the corner reflector, calculate the azimuth and pitch angles of the corner reflector. The azimuth angle of the corner reflector is the angle between the heading and the 220° north arrow. The pitch angle is the angle between the straight line perpendicular to the flight path and passing through the calibration point and the horizontal line.

[0094] Then, the bottom of the mounting bracket is supported on the ground so that the azimuth pointer 230 of the azimuth adjustment device is parallel to the horizontal plane, or in other words, the plane containing the first dial 210 is parallel to the horizontal plane. Since the second dial 310 is perpendicular to the first dial 210, when the first dial 210 is parallel to the horizontal plane, the second dial 310 automatically becomes perpendicular to the horizontal plane.

[0095] Adjust the azimuth pointer 230 so that the scale value indicated by the azimuth pointer 230 is equal to the azimuth angle. At this time, the azimuth pointer 230 is parallel to the heading.

[0096] Since the pitch angle adjustment device rotates synchronously with the azimuth pointer 230, when the azimuth pointer 230 is parallel to the flight path, the plane of rotation of the pitch angle pointer 320 is perpendicular to the flight path.

[0097] Then, adjust the pitch angle pointer 320. When the angle corresponding to the scale indicated by the pitch angle pointer 320 is equal to the pitch angle, the straight line where the pitch angle pointer 320 is located is parallel to the straight line that is perpendicular to the flight path and passes through the calibration point.

[0098] Then, by extending and retracting the mounting bracket, the height of the pitch angle adjustment device is adjusted so that the straight line where the pitch angle pointer 320 is located is collinear with the straight line perpendicular to the flight path and passing through the calibration point. At this time, the extension line of the axis of the telescopic rod of the reference component passes through the calibration point.

[0099] Finally, install the corner reflector, ensuring that the vertex of the corner reflector is located at the calibration point and that the outer surface of the triangular pyramid positioning body 420 is in contact with the inner surface of the corner reflector.

[0100] Since the triangular pyramid positioning body 420 is similar to the corner reflector, when the outer surface of the triangular pyramid positioning body 420 is in contact with the inner surface of the corner reflector, the edge of the bottom surface of the corner reflector near the opening is parallel to the bottom edge of the reference surface of the triangular pyramid positioning body 420. Consequently, the edge of the bottom surface of the corner reflector near the opening is parallel to the flight path, that is, the azimuth reference line of the corner reflector is parallel to the flight path.

[0101] Meanwhile, the reference surface of the triangular cone positioning body 420 is parallel to the opening surface of the corner reflector. Since the telescopic rod is perpendicular to the reference surface of the triangular cone positioning body 420, the telescopic rod is perpendicular to the opening surface of the corner reflector. That is, the radar wave perpendicular to the flight path and passing through the calibration point enters the corner reflector along the opening surface perpendicular to the corner reflector, and the opening surface is the surface with the largest radar cross-section.

[0102] In a further embodiment, the installation of the foot reflector includes the following steps:

[0103] Step S710: Shorten the length of the telescopic rod of the reference component, so that the triangular cone positioning body 420 moves to above the ground;

[0104] Step S720: Place the corner reflector on the ground, and make the vertex of the corner reflector coincide with the calibration point;

[0105] Step S730: Extend the telescopic rod. During the extension of the telescopic rod, adjust the angle of the corner reflector. When the vertex of the triangular pyramid positioning body 420 contacts the vertex of the inner side of the corner reflector, the side of the triangular pyramid positioning body 420 fits against the side of the corner reflector.

[0106] Specifically, before installing the corner reflector, the vertex of the triangular pyramid positioning body 420 is located at the calibration point. At this time, there is no space for installing the corner reflector, so the telescopic rod needs to be shortened to separate the triangular pyramid positioning body 420 from the ground.

[0107] Then place the corner reflector on the ground, aligning its vertex with the calibration point.

[0108] Then the telescopic rod is extended. During the extension process, the triangular pyramid positioning body 420 moves toward the vertex of the corner reflector while moving and rotating the corner reflector. Finally, the vertex of the triangular pyramid positioning body 420 contacts the inner vertex of the corner reflector. At this time, the outer surface of the triangular pyramid positioning body 420 fits against the inner surface of the corner reflector.

[0109] In the SAR ground calibration corner reflector auxiliary placement device and method provided by this invention, after the azimuth and elevation angles are adjusted to the correct positions, the attitude of the triangular pyramid positioning body 420 is the attitude of the corner reflector. The vertex of the corner reflector is placed at the calibration point, and then the telescopic rod is extended. During the extension of the telescopic rod, the angle of the corner reflector is rotated. When the vertex of the triangular pyramid positioning body 420 intersects with the inner vertex of the corner reflector, the side surface of the triangular pyramid positioning body 420 intersects with the side surface of the corner reflector, thus transferring the attitude of the triangular pyramid positioning body 420 to the corner reflector. The attitude of the corner reflector at this moment is the final attitude. The SAR ground calibration corner reflector auxiliary placement device provided by this invention can simultaneously complete the transfer of azimuth and elevation angles, avoiding the problem of the first parameter changing when adjusting the second parameter after adjusting the first parameter. Through the attitude transmission of this device, the original cumbersome placement operation of corner reflectors of different sizes is transformed into a rapid adjustment operation of the device itself, solving the practical difficulty of quickly and accurately installing corner reflectors of different specifications in the field.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An auxiliary mounting device for a SAR ground calibration angle reflector, characterized in that, include: Mounting bracket, the bottom end of which is used for support on the ground; An azimuth adjustment device is provided on the mounting frame, and the azimuth adjustment device includes an azimuth pointer (230), which is rotatably connected to the mounting frame; The pitch angle adjustment device is rotatably mounted on the mounting frame, and the pitch angle adjustment device rotates synchronously with the azimuth pointer (230). The pitch angle adjustment device includes a pitch angle pointer (320), and the plane of rotation of the pitch angle pointer (320) is perpendicular to the extension direction of the azimuth pointer (230). The reference assembly includes a telescopic link (410) and a triangular pyramid positioning body (420). One end of the telescopic link (410) is connected to the proximal end of the pitch angle pointer (320), and the other end of the telescopic link (410) extends along the axis of the pitch angle pointer (320) in a direction away from the distal end of the pitch angle pointer (320). The reference surface of the triangular pyramid positioning body (420) is connected to the end of the telescopic link (410) away from the pitch angle pointer (320). The triangular pyramid positioning body (420) is a triangular pyramid scaled down from a corner reflector. The axis of the telescopic link (410) passes through the vertex of the triangular pyramid positioning body (420). The telescopic link (410) is perpendicular to the reference surface, which is a plane opposite to the vertex of the triangular pyramid positioning body (420). The bottom edge of the reference surface is parallel to the azimuth pointer (230). The first dial (210) is rotatably connected to the mounting bracket, and when the mounting bracket is supported on the ground, the first dial (210) is parallel to the horizontal plane; A compass (220) is rotatably connected to the mounting bracket; The rotation axes of the compass (220) and the azimuth pointer (230) are both collinear with the rotation axis of the first dial (210).

2. The SAR ground calibration angle reflector auxiliary installation device according to claim 1, characterized in that, The compass (220) is fixedly connected to the first dial (210), and the compass (220) is located on the zero mark of the first dial (210).

3. The SAR ground calibration angle reflector auxiliary installation device according to claim 2, characterized in that, The pitch angle adjustment device also includes a second dial (310), which is rotatably connected to the mounting frame, and when the mounting frame is supported on the ground, the second dial (310) is perpendicular to the horizontal plane; The proximal end of the pitch angle pointer (320) is rotatably connected to the center of the second dial (310), and the axis of rotation is perpendicular to the second dial (310).

4. The SAR ground calibration angle reflector auxiliary installation device according to claim 3, characterized in that, The second dial (310) is connected to the azimuth pointer (230) in a transmission manner. The second dial (310) and the azimuth pointer (230) rotate synchronously, and the plane on which the second dial (310) is located is perpendicular to the direction of the azimuth pointer (230).

5. The SAR ground calibration angle reflector auxiliary mounting device according to any one of claims 1 to 4, characterized in that, The length of the mounting bracket is adjustable.

6. The SAR ground calibration angle reflector auxiliary placement device according to claim 4, characterized in that, Damping elements are provided between the azimuth pointer (230), the first dial (210), the second dial (310), and the pitch pointer (320) and the mounting bracket.

7. The SAR ground calibration angle reflector auxiliary installation device according to claim 4, characterized in that, A level (500) is provided on the first dial (210) and / or the second dial (310).

8. A method for installing a SAR ground calibration angle reflector, characterized in that, The method of mounting a corner reflector using the SAR ground calibration corner reflector auxiliary mounting device as described in any one of claims 1 to 7 includes: Acquire flight path information and calibration point information of the corner reflector. The flight path information includes the heading and altitude of the flight path, and the calibration point information includes the coordinates of the calibration point. Based on the flight path information and the calibration point information of the corner reflector, the azimuth and pitch angles of the corner reflector are calculated. The azimuth angle is parallel to the flight path, and the pitch angle is equal to the angle between the straight line perpendicular to the flight path and passing through the calibration point and the horizontal line. Support the bottom of the mounting bracket on the ground so that the azimuth pointer (230) of the azimuth adjustment device is parallel to the horizontal plane; Adjust the azimuth pointer (230) so that the angle corresponding to the scale pointed to by the azimuth pointer (230) is equal to the azimuth angle; Adjust the pitch angle pointer (320) so that the angle corresponding to the scale indicated by the pitch angle pointer (320) is equal to the pitch angle; Adjust the reference component so that the vertex of the triangular pyramid positioning body (420) is located at the calibration point; Install the corner reflector such that the vertex of the corner reflector is located at the calibration point, and make the outer surface of the triangular pyramid positioning body (420) fit against the inner surface of the corner reflector.

9. The SAR ground calibration angle reflector placement method according to claim 8, characterized in that, The installation of the corner reflector includes: Shorten the length of the telescopic rod of the reference component so that the triangular cone positioning body (420) moves to above the ground; Place the corner reflector on the ground, ensuring that the vertex of the corner reflector coincides with the calibration point; Extend the telescopic rod, and adjust the angle of the corner reflector during the extension process. When the vertex of the triangular pyramid positioning body (420) contacts the vertex of the inner side of the corner reflector, the side of the triangular pyramid positioning body (420) fits against the side of the corner reflector.

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