CN113640799A - Method and device for determining central irradiation point of radar beam and storage medium - Google Patents
Method and device for determining central irradiation point of radar beam and storage medium Download PDFInfo
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Abstract
The invention relates to a method, a device and a storage medium for determining a central irradiation point of a radar beam, wherein the method comprises the steps of reading code disc data of a servo platform and measurement data of a position attitude measurement unit; constructing a unit vector of the central direction of the antenna beam; calculating a coordinate vector of a unit vector in the central direction of the antenna beam in a geocentric geostationary coordinate system according to the coded disc data and the measurement data; constructing an antenna beam center direction linear equation and an earth surface ellipsoid equation according to the coordinate vector under the geocentric geostationary coordinate system; determining a radar beam center irradiation point according to the intersection point coordinates of the antenna beam center direction linear equation and the earth surface ellipsoid equation; the central irradiation point of the radar beam is determined through the intersection point coordinates of the linear equation and the ellipsoid equation on the surface of the earth, the bending factor of the earth is considered, the central irradiation point of the synthetic aperture radar beam can be accurately determined, the practicability is high, the error is small, the central irradiation point is used as a key step in the imaging of the synthetic aperture radar, and the method is suitable for realizing real-time processing of the board card.
Description
Technical Field
The invention relates to the field of synthetic aperture radars, in particular to a method and a device for determining a central irradiation point of a radar beam and a storage medium.
Background
Synthetic Aperture Radars (SAR) can realize flexible observation by controlling beam pointing during working, and can particularly realize coverage of a large area in a scanning mode. However, in data post-processing and engineering applications, if a region of interest needs to be locally imaged, it is necessary to determine whether the region is covered by a beam from data, and therefore, the precise position of the irradiation point at the center of the beam needs to be solved according to the pointing direction and the position attitude parameters of the radar antenna.
For this problem, the current method can only solve the position of the irradiation point at the center of the beam by using a flat ground hypothesis; however, under a large observation distance, the bending of the earth is a factor to be considered, and a large position calculation error is introduced by solving the position of the irradiation point at the beam center through the flat ground assumption.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method, an apparatus and a storage medium for determining a central irradiation point of a radar beam, which consider the bending factor of the earth, can accurately determine the central irradiation point of the synthetic aperture radar beam, have strong practicability and small error, and facilitate the subsequent synthetic aperture radar imaging.
The technical scheme for solving the technical problems is as follows: a method for determining a central irradiation point of a radar beam comprises the following steps:
reading code disc data of a servo platform and measurement data of a position and attitude measurement unit; the position and attitude measurement unit and the antenna are arranged on the servo platform, and the position and attitude measurement unit is connected with the antenna;
constructing a unit vector of the central direction of the antenna beam;
calculating a coordinate vector of a unit vector in the central direction of the antenna beam in a geocentric geostationary coordinate system according to the coded disc data and the measurement data;
constructing an antenna beam center direction linear equation and an earth surface ellipsoid equation according to the coordinate vector under the earth center-earth-fixed coordinate system;
and determining a central irradiation point of the radar beam according to the intersection point coordinates of the linear equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface.
The invention has the beneficial effects that: the method has the advantages that the pointed position of the antenna beam center can be known by reading code disc data of a servo platform and measurement data of a position posture measurement unit, the coordinate vector of a unit vector in the antenna beam center direction under a geocentric coordinate system is calculated through the code disc data and the measurement data, an antenna beam center direction linear equation and an earth surface ellipsoid equation are further constructed, the radar beam center irradiation point is determined through the intersection point coordinates of the linear equation and the earth surface ellipsoid equation, the bending factor of the earth is considered, the accurate determination of the synthetic aperture radar beam center irradiation point can be achieved, the practicability is high, the error is small, the calculation accuracy is high, the method is used as a key step in synthetic aperture radar imaging, and the method is suitable for real-time processing of board cards.
On the basis of the technical scheme, the invention can be further improved as follows:
further, the code wheel data includes: an azimuth code wheel angle value alpha and a pitch code wheel angle value beta;
the measurement data includes: latitude lat0Longitude lon0Height alt0Heading angle Ψ, pitch angle Θ, and roll angle Φ.
The beneficial effect of adopting the further scheme is that: by reading the angle value alpha of the azimuth code wheel and the angle value of the elevation code wheel in real time, the conversion matrix of the antenna array plane coordinate system to the position and posture measuring unit coordinate system can be conveniently determined subsequently, and by reading the latitude lat0Longitude lon0Height alt0The heading angle psi, the pitch angle theta and the roll angle phi facilitate determining a transformation matrix from a geocentric geostationary coordinate system to a northeast coordinate system and from a position attitude measurement unit coordinate system to the northeast coordinate system, and ensure accurate determination of the central irradiation point of the radar beam.
Further, the antenna beam center direction unit vector is defined in an antenna array coordinate system, and the constructing the antenna beam center direction unit vector includes:
UA＝[1,0,0]T。
the beneficial effect of adopting the further scheme is that: and the subsequent calculation of the coordinate vector of the unit vector of the central direction of the antenna beam in the geocentric geostationary coordinate system is facilitated.
Further, the calculating the coordinate vector of the unit vector of the antenna beam center direction in the geocentric geostationary coordinate system according to the code disc data and the measurement data includes:
determining a conversion matrix C of an antenna array surface coordinate system to a position and attitude measurement unit coordinate system according to code disc datar；
According to the latitude lat in the measured data0Longitude lon0Height alt0Determining a transformation matrix S from the geocentric geostationary coordinate system to the northeast geodetic coordinate system;
determining a conversion matrix C from a position and attitude measurement unit coordinate system to a northeast coordinate system according to a heading angle psi, a pitch angle theta and a roll angle phi in the measurement datag；
According to the unit vector U of the antenna beam center directionAConversion matrix CrA transformation matrix S and a transformation matrix CgDetermining a coordinate vector U of a unit vector of the central direction of an antenna beam in a geocentric geostationary coordinate systemE，
UE＝S-1·Cg·Cr·UA。
The beneficial effect of adopting the further scheme is that: and calculating the coordinate vector of the unit vector of the central direction of the antenna beam in the geocentric geostationary coordinate system based on the code disc data and the measurement data, and ensuring the accurate determination of the subsequent central irradiation point.
Further, the constructing of the antenna beam center direction linear equation and the earth surface ellipsoid equation according to the coordinate vector under the geocentric geostationary coordinate system includes:
setting a coordinate vector U of a unit vector in the central direction of an antenna beam in a geocentric geostationary coordinate systemE，
UE＝[a,b,c]T
a. b and c are respectively vectors UEA direction vector coordinate value of (a);
the expression of the linear equation of the central direction of the antenna beam is as follows:
wherein (x)0,y0,z0) For measuring the position coordinates (lat) of the unit0,lon0,alt0) Converting the coordinates into coordinates under a geocentric geostationary coordinate system; (x, y, z) is a straight-line function unknown quantity of a geocentric coordinate system;
the expression of the surface ellipsoid equation of the earth is as follows:
wherein Ra is the length of the earth's major semi-axis, Rb is the length of the earth's minor semi-axis, and h is the elevation of the earth's surface.
The beneficial effect of adopting the further scheme is that: by means of the linear equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface, linear emission of the antenna beam and bending of the earth are used as determining factors of the irradiation point at the beam center, and accuracy and reliability of determination of the irradiation point are guaranteed.
Further, before determining the radar beam center irradiation point according to the intersection coordinates of the antenna beam center direction straight line equation and the earth surface ellipsoid equation, the method comprises the following steps:
define the parameter A, B, C, expressed as:
A＝a2(Rb+h)2+b2(Rb+h)2+c2(Ra+h)2
B＝-2a2(Rb+h)2z0+2ac(Rb+h)2x0-2b2(Rb+h)2z0+2bc(Rb+h)2y0
determining x and y in the antenna beam center direction linear equation according to the antenna beam center direction linear equation expression as follows:
obtaining z in an antenna beam center direction linear equation according to the reference A, B, C and a quadratic equation;
and substituting the x, y and z into intersection coordinates (x ', y ', z ') of the earth surface ellipsoid equation expression.
The beneficial effect of adopting the further scheme is that: the central irradiation point of the radar beam is determined through the intersection point coordinates of the linear equation and the ellipsoid equation on the surface of the earth, the bending factor of the earth is considered, the central irradiation point of the synthetic aperture radar beam can be accurately determined, the practicability is high, and the synthetic aperture radar imaging can be conveniently realized according to the coverage area.
Further, let the intermediate variable L ═ z' · z0If L is larger than or equal to 0, keeping the intersection point coordinate of the group where z' is located; if L is less than 0, abandoning the intersection point coordinates (x ', y', z ') of the group where z' is located; (ii) a
And (4) carrying out coordinate transformation on the reserved intersection point coordinates (x ', y ', z ') to obtain longitude and latitude height coordinates of the irradiation point of the antenna beam center on the earth surface.
The beneficial effect of adopting the further scheme is that: the intersection point coordinates are screened by judging whether L is greater than or equal to 0, and the determination precision of the beam center irradiation point is improved.
Further, the longitude and latitude height coordinates are defined under the WGS-84 coordinate system.
The beneficial effect of adopting the further scheme is that: the longitude and latitude height coordinates are defined in a WGS-84 coordinate system, the application is wide, and the synthetic aperture radar imaging in the subsequent coverage area can be conveniently realized.
In order to solve the above technical problem, the present invention further provides a radar beam center irradiation point determining apparatus, including: a memory for storing a computer program;
a processor for executing said computer program for carrying out the steps of the method for determining a central irradiation point of a radar beam as described above.
In order to solve the above technical problem, the present invention further provides a storage medium storing one or more computer programs, which are executable by one or more processors to implement the steps of the radar beam center irradiation point determination method as described above.
Drawings
Fig. 1 is a flowchart of a method for determining a central irradiation point of a radar beam according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a servo platform and a code wheel turning angle according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an antenna array coordinate system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a coordinate system of a position and orientation measurement unit according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a radar beam center irradiation point determining apparatus according to an embodiment of the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, fig. 1 is a flowchart of a method for determining a central irradiation point of a radar beam according to an embodiment of the present invention, where the method for determining a central irradiation point of a radar beam includes:
s1, reading code disc data of the servo platform and measurement data of the position and posture measurement unit; the antenna is arranged on the servo platform, and the position and posture measuring unit is connected with the antenna;
s2, constructing a unit vector of the central direction of the antenna beam;
s3, calculating a coordinate vector of the unit vector of the antenna beam center direction in the geocentric geostationary coordinate system according to the code disc data and the measurement data;
s4, constructing an antenna beam center direction linear equation and an earth surface ellipsoid equation according to the coordinate vector under the geocentric geostationary coordinate system;
and S5, determining the irradiation point of the center of the radar beam according to the intersection point coordinates of the straight line equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface.
In the embodiment, the position pointed by the antenna beam center can be known by reading code disc data of a servo platform and measurement data of a position posture measurement unit, a coordinate vector of a unit vector of the antenna beam center direction under a geocentric geostationary coordinate system is calculated through the code disc data and the measurement data, an antenna beam center direction linear equation and an earth surface ellipsoid equation are further constructed, a radar beam center irradiation point is determined through intersection coordinates of the linear equation and the earth surface ellipsoid equation, bending factors of the earth are considered, accurate determination of the synthetic aperture radar beam center irradiation point can be achieved, the practicability is strong, the error is small, the calculation accuracy is high, the method is used as a key step in synthetic aperture radar imaging, and the method is suitable for real-time processing of board cards.
In the present embodiment, the code wheel data includes: an azimuth code wheel angle value alpha and a pitch code wheel angle value beta; as shown in fig. 2, the antenna is installed on the servo platform, the position and attitude measurement unit is also installed on the servo platform, the two-axis platform is required for the servo platform, and the azimuth code wheel angle value α and the pitch code wheel angle value β of the servo platform can be read in real time, wherein in an initial state, namely when an antenna beam is not transmitted, the azimuth code wheel angle value and the pitch code wheel angle value pointed by the center of the antenna beam are both zero; in other embodiments, the position code wheel angle value α and the tilt code wheel angle value β may also be read after a preset time period, for example, after 10s after the antenna beam is transmitted, so as to reduce resource consumption.
The measurement data includes: latitude lat0Longitude lon0Height alt0Heading angle Ψ, pitch angle Θ, and roll angle Φ. As shown in fig. 3, the position and orientation measuring unit is connected to the antenna, wherein the position and orientation measuring unit is fixedly connected to the antenna, preferably, the position and orientation measuring unit is rigidly connected to the antenna, and the latitude lat of the position and orientation measuring unit can be read in real time0Longitude lon0Height alt0A course angle psi, a pitch angle theta and a roll angle phi, wherein in an initial state, the axial direction and the same direction are positioned when the angle value between the X axis of the coordinate system of the position attitude measurement unit and the azimuth code disc of the servo platform is zero; in other embodiments, the measurement data of the position and orientation measurement unit may also be read after a preset time period.
It should be noted that, the unit vector of the central direction of the antenna beam is defined in the antenna array plane coordinate system, as shown in fig. 4, where the X axis of the antenna array plane coordinate system is perpendicular to the antenna array plane and points to the electromagnetic wave propagation direction, the Y axis is parallel to the antenna array plane and is the X axis and rotates clockwise by 90 °, and the Z axis and the X axis and the Y axis satisfy the right-handed helical method, and then the Z axis points downward, where the antenna array plane is a planar array formed by the antenna array. Constructing unit vector U of antenna beam center directionAThe method comprises the following steps:
UA＝[1,0,0]T；
in this embodiment, calculating the coordinate vector of the unit vector of the antenna beam center direction in the geocentric geostationary coordinate system according to the code wheel data and the measurement data specifically includes:
determining a conversion matrix C of an antenna array surface coordinate system to a position and attitude measurement unit coordinate system according to code disc datar；
According to the latitude lat in the measured data0Longitude lon0Height alt0Determining a transformation matrix S from the geocentric geostationary coordinate system to the northeast geodetic coordinate system;
determining a conversion matrix C from a position and attitude measurement unit coordinate system to a northeast coordinate system according to a heading angle psi, a pitch angle theta and a roll angle phi in the measurement datag；
In an antenna beamCoordinate vector U of unit vector in heart direction in earth-center-earth-fixed coordinate systemEComprises the following steps:
UE＝S-1·Cg·Cr·UA
wherein S is represented by:
Cgexpressed as:
Crexpressed as:
in this embodiment, constructing the linear equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface according to the coordinate vector in the geocentric geostationary coordinate system includes:
due to UE＝S-1·Cg·Cr·UAThen U isECorresponding to a specific coordinate vector, converting the specific coordinate vector into UE＝[a,b,c]TA, b, c are vectors U respectivelyEThe coordinate value of the direction vector is obtained, and the expression of the constructed linear equation of the central direction of the antenna beam is as follows:
wherein (x)0,y0,z0) For measuring the position coordinates (lat) of the unit0,lon0,alt0) Converting the coordinates into coordinates under a geocentric geostationary coordinate system; (x, y, z) is a straight-line function unknown quantity of a geocentric coordinate system;
the expression of the surface ellipsoid equation of the earth is as follows:
wherein Ra is the length of the earth's major semi-axis, Rb is the length of the earth's minor semi-axis, and h is the elevation of the earth's surface.
In this embodiment, before determining the radar beam center irradiation point according to the intersection coordinates of the antenna beam center direction linear equation and the earth surface ellipsoid equation, it is further required to determine a linear function unknown quantity (x, y, z) of the geocentric coordinate system;
specifically, a parameter A, B, C is defined, which is expressed as:
A＝a2(Rb+h)2+b2(Rb+h)2+c2(Ra+h)2
B＝-2a2(Rb+h)2z0+2ac(Rb+h)2x0-2b2(Rb+h)2z0+2bc(Rb+h)2y0
determining x and y in the antenna beam center direction linear equation according to the antenna beam center direction linear equation expression as follows:
and obtaining z in the antenna beam center direction linear equation according to the reference A, B, C and a one-dimensional quadratic equation:
and substituting the x, y and z into intersection coordinates (x ', y ', z ') of the earth surface ellipsoid equation expression.
In this embodiment, in order to improve the accuracy of determining the longitude and latitude height coordinates, it is necessary to filter coordinates, specifically, let the intermediate variable L be z' z0If L is larger than or equal to 0, keeping the intersection point coordinate of the group where z' is located; if L is less than 0, abandoning the intersection point coordinates (x ', y', z ') of the group where z' is located;
and (4) carrying out coordinate transformation on the reserved intersection point coordinates (x ', y ', z ') to obtain longitude and latitude height coordinates of the irradiation point of the antenna beam center on the earth surface. Optionally, the specific coordinate transformation is a transformation equation from a geodetic fixed (ECEF) coordinate system to a longitude and latitude height (LLA) coordinate system.
In the present embodiment, the longitude and latitude height coordinates are defined under the WGS-84 coordinate system, and thus the remaining intersection coordinates (x ', y ', z ') can be converted to the longitude and latitude height coordinates under the WGS-84 coordinate system.
It can be understood that after the central irradiation point of the synthetic aperture radar beam is accurately determined, the coverage area of the antenna beam can be determined according to the coordinate point, and then the coverage area can be locally imaged.
For convenience of understanding, simulation can be performed through software such as Matlab, as shown in table 1, where table 1 is two sets of experimental parameters, and the ground intersection point coordinates obtained by the experimental data of table 1 through the method for determining the radar beam center irradiation point in this embodiment are shown in table 2.
TABLE 1
| Parameter(s) | Value 1 | Number 2 |
| Latitude of antenna | 39° | 42° |
| Antenna longitude | 110° | 120° |
| Height of antenna | 8000m | 3000m |
| Servo pitch angle | 30° | 45° |
| Servo azimuth angle | 90° | 70° |
| Course angle | 60° | 20° |
| Pitch angle | 5° | 2° |
| Roll angle | 10° | 6° |
| Altitude at ground | 1500m | 300m |
| Terrestrial coordinate system | WGS-84 | WGS-84 |
TABLE 2
| Data of | Latitude | Longitude (G) | Height |
| First group | 38.941861° | 110.050551° | 1499.9980m |
| Second group | 42.001643° | 120.027456° | 299.9996m |
In this embodiment, the solving accuracy of the method can be obtained by comparing the heights. The reference height of the first set of experiments is 1500m, the solving height is 1499.9980m, and the solving precision is 0.002 m. The reference height of the second set of experiments was 300m, the solving height was 299.9996m, and the solving accuracy was 0.0004 m. Under the condition that iterative solution is not needed, the solution precision meets the requirement of practical application.
The present embodiment further provides an apparatus for determining a central irradiation point of a radar beam, as shown in fig. 5, the apparatus includes:
a memory 51 for storing a computer program;
the processor 52 is configured to execute the computer program to implement the steps of the method for determining a central irradiation point of a radar beam as described above, which are not described herein again.
The present embodiment further provides a storage medium, where one or more computer programs are stored in the storage medium, and the one or more computer programs may be executed by one or more processors to implement the steps of the method for determining a central irradiation point of a radar beam as described above, which are not described herein again.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, a division of a unit is merely a logical division, and an actual implementation may have another division, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment of the present invention.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The technical solutions provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained in this patent by applying specific examples, and the descriptions of the embodiments above are only used to help understanding the principles of the embodiments of the present invention; the present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for determining a central irradiation point of a radar beam is characterized by comprising the following steps:
reading code disc data and position and attitude measurement unit measurement data of a servo platform; the position and attitude measurement unit and the antenna are arranged on the servo platform, and the position and attitude measurement unit is connected with the antenna;
constructing a unit vector of the central direction of the antenna beam;
calculating a coordinate vector of a unit vector in the central direction of the antenna beam in a geocentric geostationary coordinate system according to the coded disc data and the measurement data;
constructing an antenna beam center direction linear equation and an earth surface ellipsoid equation according to the coordinate vector under the earth center-earth-fixed coordinate system;
and determining a central irradiation point of the radar beam according to the intersection point coordinates of the linear equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface.
2. The method of claim 1, wherein the code wheel data includes: an azimuth code wheel angle value alpha and a pitch code wheel angle value beta;
the measurement data includes: latitude lat0Longitude lon0Height alt0Heading angle Ψ, pitch angle Θ, and roll angle Φ.
3. The method for determining the central irradiation point of the radar beam according to claim 2, wherein the unit vector of the central direction of the antenna beam is defined in an antenna array plane coordinate system, an X axis of the antenna array plane coordinate system is perpendicular to an antenna array plane, a Y axis is parallel to the antenna array plane, the X axis rotates clockwise by 90 degrees, and a Z axis, the X axis and the Y axis satisfy a right-handed helical method;
the constructing of the antenna beam center direction unit vector comprises:
the coordinate vector expression of the unit vector of the antenna beam center direction in the antenna array plane coordinate system is as follows:
UA＝[1,0,0]T。
4. the method for determining a central illumination point of a radar beam according to claim 3, wherein the calculating a coordinate vector of a unit vector of the central direction of the antenna beam in a geocentric and geostationary coordinate system according to the code wheel data and the measurement data comprises:
determining a conversion matrix C of an antenna array surface coordinate system to a position and attitude measurement unit coordinate system according to code disc datar；
According to the latitude lat in the measured data0Longitude lon0Height alt0Determining a transformation matrix S from the geocentric geostationary coordinate system to the northeast geodetic coordinate system;
based on measured dataThe medium heading angle psi, the pitch angle theta and the roll angle phi determine a transformation matrix C from a coordinate system of the position and attitude measurement unit to a coordinate system of the northeastg；
According to the unit vector U of the antenna beam center directionAConversion matrix CrA transformation matrix S and a transformation matrix CgDetermining a coordinate vector U of a unit vector of the central direction of an antenna beam in a geocentric geostationary coordinate systemE，
UE＝S-1·Cg·Cr·UA。
5. The method of claim 4, wherein the constructing the linear equation of the central direction of the antenna beam and the ellipsoid equation of the earth surface from the coordinate vectors in the geocentric and geostationary coordinate system comprises:
setting a coordinate vector U of a unit vector in the central direction of an antenna beam in a geocentric geostationary coordinate systemE，
UE＝[a,b,c]T
a. b and c are respectively vectors UEA direction vector coordinate value of (a);
the expression of the linear equation of the central direction of the antenna beam is as follows:
wherein (x)0,y0,z0) For measuring the position coordinates (lat) of the unit0,lon0,alt0) Converting the coordinates into coordinates under a geocentric geostationary coordinate system; (x, y, z) is a straight-line function unknown quantity of a geocentric coordinate system;
the expression of the surface ellipsoid equation of the earth is as follows:
wherein Ra is the length of the earth's major semi-axis, Rb is the length of the earth's minor semi-axis, and h is the elevation of the earth's surface.
6. The method of claim 5, wherein the determining the radar beam center irradiation point according to the coordinates of the intersection point of the antenna beam center direction straight line equation and the earth surface ellipsoid equation comprises:
define the parameter A, B, C, expressed as:
A＝a2(Rb+h)2+b2(Rb+h)2+c2(Ra+h)2
B＝-2a2(Rb+h)2z0+2ac(Rb+h)2x0-2b2(Rb+h)2z0+2bc(Rb+h)2y0
determining x and y in the antenna beam center direction linear equation according to the antenna beam center direction linear equation expression as follows:
obtaining z in the linear equation of the central direction of the antenna beam according to the reference A, B, C and a quadratic equation;
and substituting the x, y and z into intersection coordinates (x ', y ', z ') of the earth surface ellipsoid equation expression.
7. The method of claim 6, wherein the determining the radar beam center illumination point comprises:
let the intermediate variable L be z' z0If L is larger than or equal to 0, keeping the intersection point coordinate of the group where z' is located; if L is less than 0, abandoning the intersection point coordinates (x ', y', z ') of the group where z' is located;
and (4) carrying out coordinate transformation on the reserved intersection point coordinates (x ', y ', z ') to obtain longitude and latitude height coordinates of the irradiation point of the antenna beam center on the earth surface.
8. The method of claim 7, wherein the longitude and latitude height coordinates are defined in the WGS-84 coordinate system.
9. A radar beam center irradiation point determination apparatus, comprising:
a memory for storing a computer program;
a processor for executing said computer program for carrying out the steps of the method for radar beam center illumination point determination according to any one of claims 1 to 8.
10. A storage medium storing one or more computer programs executable by one or more processors to perform the steps of the radar beam center irradiation point determination method according to any one of claims 1 to 8.
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| CN115276760A (en) * | 2022-06-24 | 2022-11-01 | 中国联合网络通信集团有限公司 | Method and device for determining position of beam center and computer storage medium |
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