CN116840796A - Calculation and analysis method and system for space synchronization rate of formation SAR satellite - Google Patents
Calculation and analysis method and system for space synchronization rate of formation SAR satellite Download PDFInfo
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Abstract
The application provides a calculation and analysis method and a system for space synchronization rate of formation SAR satellites, comprising the following steps: calculating and obtaining a double-star attitude guide angle according to the respective orbit parameters of the double stars at the analysis moment; calculating respective imaging areas of the double satellites according to satellite position, attitude information and beam information; and analyzing the double-star space synchronization rate according to the double-star imaging area and considering various influences of engineering errors. Aiming at the deformation correction requirement of the satellite in-orbit image, the real-time guiding condition of the satellite in-orbit attitude is considered during analysis, and the real-time guiding condition is close to the actual in-orbit state; according to the application, engineering practice is considered, so that the space synchronization design and the control of various errors in the practical development can be guided, and the analysis of indexes such as space synchronization rate of formation SAR satellites is effectively supported; the application has wide application stage and can be used in index analysis and demonstration stage, development and test stage and long-term on-orbit operation stage.
Description
Technical Field
The application relates to the field of formation satellite index ground calculation analysis demonstration, in particular to a calculation analysis method and a calculation analysis system for formation SAR satellite space synchronization rate.
Background
The satellite in-orbit flight is influenced by the earth rotation and the elliptical orbit, and the problems of image position deviation, image deformation and the like can occur during satellite imaging. In particular, for SAR satellites, the doppler center shifts due to the curvature of the earth and the existence of rotation, and typical shift values are higher than the system pulse repetition frequency, affecting image quality. Therefore, the SAR satellite on-orbit flight attitude generally operates according to a designed two-dimensional attitude guidance rule so as to improve imaging quality and simplify the post-processing process.
The interference synthetic aperture radar system utilizes echo data obtained by observing a plurality of receiving antennas of the formation SAR satellite to carry out interference processing, and can estimate the elevation of the ground, measure the height and speed of sea current and detect and position the ground moving target. Any one star participating in formation transmits signals in a one-transmission-multiple-reception mode of the system, two stars simultaneously receive signals, and the time loss is almost zero, but the problem of space synchronization must be solved, namely, the alignment auxiliary satellite attitude adjustment is carried out when necessary through the formation configuration design, so that the two-star observation areas are overlapped as much as possible. The time loss is zero, which means that the InSAR system transmits and receives, the time is synchronous, and the possibility of image incoherence caused by longer time interval does not exist. In the ground index demonstration stage, analysis and calculation are needed for the space synchronization rate of the formation satellites so as to verify whether the adopted measures are effective or not and whether the analysis can meet the requirements or not.
Patent document CN112327262a discloses an on-orbit calibration method and system for the directional consistency of the distributed InSAR satellite SAR beams, which are suitable for calibrating and maintaining the directional consistency of the distributed InSAR satellite SAR beams under a double-star (one-shot and two-shot) system or a multi-star (one-shot and multi-shot) system, and solve the problems that the distributed InSAR satellite runs on-orbit and the dual-star SAR beams are inconsistent in directional, the temperature environment of the dual-star SAR is inconsistent due to inconsistent dual-star receiving and transmitting states in the imaging process, and further the dual-star SAR beams are caused to point deviation, so that the auxiliary star receiving energy is reduced, the dual-star coherence is poor, the mapping precision is affected, and the like. However, patent document CN112327262a does not relate to a method of evaluating and calculating the synchronization rate.
Patent document CN102967851a discloses a spatial synchronization method of bistatic SAR, which introduces a method for generating pointing control parameters of an airborne bistatic SAR antenna through coordinate transformation based on GPS spatial coordinate information and attitude information of an airborne platform. However, patent document CN102967851a only relates to a method for achieving synchronization by adjusting the antenna beam direction, and is not applicable to a large phased array antenna which cannot be directly driven on the track because of the inability of an antenna having no beam scanning ability.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a calculation and analysis method and a system for the space synchronization rate of a formation SAR satellite.
The application provides a calculation and analysis method for space synchronization rate of formation SAR satellites, which comprises the following steps:
step S1: acquiring a satellite attitude guide angle of a double star;
step S2: calculating respective imaging areas of the double satellites according to the satellite attitude guide angles;
step S3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
Preferably, in the step S1, calculating to obtain the satellite attitude guidance angle of the double star according to the respective orbit parameters of the double star at the analysis time in the source data includes:
step S1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotation angular velocity of the earth;
step S1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity, f is the true near point angle;
step S1.3: obtaining a satellite attitude guide angle according to the yaw guide angle phi and the pitch guide angle thetaWherein-> Indicating the roll direction guide angle.
Preferably, in the step S2, calculating the respective imaging areas of the two satellites according to the satellite attitude guidance angle, and the range-wise beam width and the azimuth-wise beam width in the source data includes:
step S2.1: selecting a wave position to be analyzed, and determining a beam pointing angle alpha and a distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the wave position to be analyzed covers the near-end wave position, the central wave position and the far-end wave position;
step S2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field;
step S2.3: and calculating a ground imaging area according to the satellite attitude guide angle and the cone-shaped view angle range, namely sequentially determining intersection points of four edges of the cone-shaped view field and the earth.
Preferably, the step S2.3 includes:
step S2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) represents the first element of the angle matrix A1;
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2;
wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3;
wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4;
step S2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
step S2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
step S2.3.4: after solving to obtain the position coordinates of the ellipsoidal intersection point of the space straight line and the ellipsoidal intersection point, converting the position coordinates into longitude and latitude descriptions, and respectively obtaining imaging areas of the longitude and latitude descriptions for the formation double stars.
Preferably, the method further comprises:
step S4: and analyzing the overlapping rate of the imaging region after engineering errors are added.
The application provides a calculation and analysis system for space synchronization rate of formation SAR satellites, which comprises the following components:
module M1: acquiring a satellite attitude guide angle of a double star;
module M2: calculating respective imaging areas of the double satellites according to the satellite attitude guide angles;
module M3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
Preferably, the calculating in the module M1 to obtain the satellite attitude guidance angle of the double star according to the respective orbit parameters of the double star at the analysis time in the source data includes:
module M1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotation angular velocity of the earth;
module M1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity, f is the true near point angle;
module M1.3: obtaining a satellite attitude guide angle according to the yaw guide angle phi and the pitch guide angle thetaWherein-> Indicating the roll direction guide angle.
Preferably, the calculating, in the module M2, the respective imaging areas of the two satellites according to the satellite attitude guidance angle, and the distance beam width and the azimuth beam width in the source data includes:
module M2.1: selecting a wave position to be analyzed, and determiningBeam pointing angle alpha and distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the wave position to be analyzed covers the near-end wave position, the central wave position and the far-end wave position;
module M2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field;
module M2.3: and calculating a ground imaging area according to the satellite attitude guide angle and the cone-shaped view angle range, namely sequentially determining intersection points of four edges of the cone-shaped view field and the earth.
Preferably, the module M2.3 comprises:
module M2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) represents the first element of the angle matrix A1;
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2;
wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3;
wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4;
module M2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
module M2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
module M2.3.4: after solving to obtain the position coordinates of the ellipsoidal intersection point of the space straight line and the ellipsoidal intersection point, converting the position coordinates into longitude and latitude descriptions, and respectively obtaining imaging areas of the longitude and latitude descriptions for the formation double stars.
Preferably, the method further comprises:
module M4: and analyzing the overlapping rate of the imaging region after engineering errors are added.
Compared with the prior art, the application has the following beneficial effects:
1. according to the method, aiming at the deformation correction requirement of the satellite in-orbit image, the real-time guiding condition of the satellite in-orbit attitude is considered during analysis, and the space synchronization effect can be effectively analyzed, estimated and evaluated by utilizing the double-satellite position, the attitude and the imaging wave position information, so that the method is close to the actual in-orbit state.
2. The application considers engineering practice, can guide the space synchronization design and control various errors in the practical development, and effectively supports the analysis of index demonstration such as space synchronization rate of formation SAR satellites.
3. The application has wide application stage, can be used in index analysis and demonstration stage, development and test stage and long-term on-orbit operation stage, and has commonality because the input parameters related in the application are satellite orbit attitude and SAR load conventional parameters.
4. The application performs space synchronization through satellite attitude adjustment, and can be suitable for large phased array antennas which cannot be directly driven in orbit.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a conceptual diagram of spatial synchronization and synchronization rate analysis according to the present application.
Fig. 2 is a schematic diagram of a three-dimensional attitude guidance calculation flow of formation satellite space synchronization according to the present application.
FIG. 3 is a graph showing the change of the spatial synchronization rate with the latitude amplitude angle calculated for the formation satellites by adopting the application.
FIG. 4 is a graph showing the change of the spatial synchronization rate with the geographic latitude calculated for the formation satellites using the present application.
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
The application discloses a calculation and analysis method of formation SAR satellite space synchronization rate according to formation satellite space synchronization interference imaging requirements, which is shown in figure 1, and relates to a method for calculating double-star space synchronization rate according to double-star position, attitude and imaging wave position information. Firstly, calculating and obtaining a double-star attitude guide angle according to respective orbit parameters of double stars at the analysis moment; calculating respective imaging areas of the double satellites according to satellite position, attitude information and beam information; and analyzing the double-star space synchronization rate according to the double-star imaging area and considering various influences of engineering errors.
As shown in fig. 2, the method for calculating and analyzing the space synchronization rate of the formation SAR satellite according to the present application includes:
step S1: and calculating and obtaining the double-star attitude guide angle according to the respective orbit parameters of the double stars at the analysis moment in the source data. The step S1 specifically comprises the following steps:
step S1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotational angular velocity of the earth.
Step S1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity and f is the true near point angle.
Step S1.3: obtaining a satellite attitude guide angle according to the yaw guide angle phi and the pitch guide angle thetaWherein-> Indicating the roll direction guide angle.
Step S2: and calculating respective imaging areas of the double stars according to the attitude guide angle, the distance beam width and the azimuth beam width in the source data. The step S2 specifically includes the following steps:
step S2.1: selecting a wave position to be analyzed, and determining a beam pointing angle alpha and a distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein the wave position to be analyzed preferably covers the near-end wave position, the central wave position and the far-end wave position.
Step S2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field.
Step S2.3: and calculating a ground imaging area according to the information such as the attitude guide angle, the cone-shaped view angle range and the like, namely sequentially determining the intersection points of four edges of the cone-shaped view field and the earth. The step S2.3 includes:
step S2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) the first element of the angle matrix A1
The other three edges are calculated by the same method, namely:
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2.
Wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3.
Wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4.
Step S2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
step S2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
step S2.3.4: after the position coordinates of the ellipsoidal intersection points of the space straight line and the ellipsoidal intersection points are obtained through solving, the position coordinates are converted into longitude and latitude descriptions, and therefore imaging areas for longitude and latitude descriptions of the formation double stars are obtained respectively.
Step S3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
Step S4: and analyzing the overlapping rate of the imaging region after engineering errors are added. Specifically, by superposing information such as double-star position errors, attitude determination errors, beam pointing errors and the like on source data, the spatial synchronization rate achievable by engineering and the influence condition of each error on the spatial synchronization are analyzed and determined.
As shown in fig. 3 and 4, fig. 3 shows a schematic diagram of the change of the spatial synchronization rate calculated for the formation satellite according to the application along with the latitude, and fig. 4 shows a schematic diagram of the change of the spatial synchronization rate calculated for the formation satellite according to the application along with the geographic latitude. The space synchronization rate of the formation satellite is better than 96.5%.
The application also provides a system for calculating and analyzing the space synchronization rate of the formation SAR satellite, which can be realized by a person skilled in the art through executing the flow steps of the method for calculating and analyzing the space synchronization rate of the formation SAR satellite, namely the method for calculating and analyzing the space synchronization rate of the formation SAR satellite can be understood as a preferred implementation mode of the system for calculating and analyzing the space synchronization rate of the formation SAR satellite.
Those skilled in the art will appreciate that the systems, apparatus, and their respective modules provided herein may be implemented entirely by logic programming of method steps such that the systems, apparatus, and their respective modules are implemented as logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc., in addition to the systems, apparatus, and their respective modules being implemented as pure computer readable program code. Therefore, the system, the apparatus, and the respective modules thereof provided by the present application may be regarded as one hardware component, and the modules included therein for implementing various programs may also be regarded as structures within the hardware component; modules for implementing various functions may also be regarded as being either software programs for implementing the methods or structures within hardware components.
Specifically, the system for calculating and analyzing the space synchronization rate of the formation SAR satellite provided by the application comprises the following components:
module M1: acquiring a satellite attitude guide angle of a double star;
module M2: calculating respective imaging areas of the double satellites according to the satellite attitude guide angles;
module M3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
Preferably, the calculating in the module M1 to obtain the satellite attitude guidance angle of the double star according to the respective orbit parameters of the double star at the analysis time in the source data includes:
module M1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotation angular velocity of the earth;
module M1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity, f is the true near point angle;
module M1.3: obtaining a satellite attitude guide angle according to the yaw guide angle phi and the pitch guide angle thetaWherein-> Indicating the roll direction guide angle.
Preferably, the calculating, in the module M2, the respective imaging areas of the two satellites according to the satellite attitude guidance angle, and the distance beam width and the azimuth beam width in the source data includes:
module M2.1: selecting a wave position to be analyzed, and determining a beam pointing angle alpha and a distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the wave position to be analyzed covers the near-end wave position, the central wave position and the far-end wave position;
module M2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field;
module M2.3: and calculating a ground imaging area according to the satellite attitude guide angle and the cone-shaped view angle range, namely sequentially determining intersection points of four edges of the cone-shaped view field and the earth.
Preferably, the module M2.3 comprises:
module M2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) represents the first element of the angle matrix A1;
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2;
wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3;
wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4;
module M2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
module M2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
module M2.3.4: after solving to obtain the position coordinates of the ellipsoidal intersection point of the space straight line and the ellipsoidal intersection point, converting the position coordinates into longitude and latitude descriptions, and respectively obtaining imaging areas of the longitude and latitude descriptions for the formation double stars.
Preferably, the method further comprises:
module M4: and analyzing the overlapping rate of the imaging region after engineering errors are added.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (10)
1. The calculation and analysis method for the space synchronization rate of the formation SAR satellite is characterized by comprising the following steps of:
step S1: acquiring a satellite attitude guide angle of a double star;
step S2: calculating respective imaging areas of the double satellites according to the satellite attitude guide angles;
step S3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
2. The method according to claim 1, wherein the calculating and analyzing the space-time synchronization rate of the formed SAR satellites in step S1 calculates and obtains the satellite attitude guidance angles of the double satellites according to the respective orbit parameters of the double satellites at the analysis time in the source data, and includes:
step S1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotation angular velocity of the earth;
step S1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity, f is the true near point angle;
step S1.3: according to the yaw guide angle psi and the pitch guide angleθ, obtain satellite attitude guidance angleWherein the method comprises the steps of Indicating the roll direction guide angle.
3. The method according to claim 1, wherein the calculating and analyzing the space-time synchronization rate of the formed SAR satellites in step S2 calculates the respective imaging areas of the double satellites according to the satellite attitude guidance angle, and the range-wise beam width and the azimuth beam width in the source data, and includes:
step S2.1: selecting a wave position to be analyzed, and determining a beam pointing angle alpha and a distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the wave position to be analyzed covers the near-end wave position, the central wave position and the far-end wave position;
step S2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field;
step S2.3: and calculating a ground imaging area according to the satellite attitude guide angle and the cone-shaped view angle range, namely sequentially determining intersection points of four edges of the cone-shaped view field and the earth.
4. A method of computational analysis of the spatial synchronization rate of a formation SAR satellite according to claim 3, wherein said step S2.3 comprises:
step S2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) represents the first element of the angle matrix A1;
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2;
wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3;
wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4;
step S2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
step S2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
step S2.3.4: after solving to obtain the position coordinates of the ellipsoidal intersection point of the space straight line and the ellipsoidal intersection point, converting the position coordinates into longitude and latitude descriptions, and respectively obtaining imaging areas of the longitude and latitude descriptions for the formation double stars.
5. The method of computational analysis of the spatial synchronization rate of a formation SAR satellite according to claim 1, further comprising:
step S4: and analyzing the overlapping rate of the imaging region after engineering errors are added.
6. A computational analysis system for space-time synchronization rate of a formation SAR satellite, comprising:
module M1: acquiring a satellite attitude guide angle of a double star;
module M2: calculating respective imaging areas of the double satellites according to the satellite attitude guide angles;
module M3: and calculating the overlapping rate of the imaging areas of the double stars according to the imaging areas of the double stars, and completing the analysis and calculation of the space synchronization rate.
7. The system according to claim 6, wherein the calculating and analyzing the satellite attitude guidance angles of the two stars in the module M1 according to the respective orbit parameters of the two stars at the analysis time in the source data includes:
module M1.1: the yaw guide angle ψ is calculated:
wherein: i is the track inclination angle, u is the latitude amplitude angle and omega s For real-time angular velocity, ω, of satellite in orbit e Is the rotation angular velocity of the earth;
module M1.2: calculating a pitching guide angle theta:
wherein: e is the track eccentricity, f is the true near point angle;
module M1.3: obtaining a satellite attitude guide angle according to the yaw guide angle phi and the pitch guide angle thetaWherein the method comprises the steps of Indicating the roll direction guide angle.
8. The method according to claim 6, wherein the calculating the two-star imaging region according to the satellite attitude guidance angle and the range-wise beam width and the azimuth beam width in the source data in the module M2 comprises:
module M2.1: selecting a wave position to be analyzed, and determining a beam pointing angle alpha and a distance beam width beta of the wave position W Azimuth beam width beta L The method comprises the steps of carrying out a first treatment on the surface of the Wherein, the wave position to be analyzed covers the near-end wave position, the central wave position and the far-end wave position;
module M2.2: beam pointing angle alpha and distance beam width beta according to the wave position W Azimuth beam width beta L Determining a cone field angle range:
wherein A1, A2, A3 and A4 respectively represent the matrix of angles between four edges and the central line of the SAR cone-shaped view field;
module M2.3: and calculating a ground imaging area according to the satellite attitude guide angle and the cone-shaped view angle range, namely sequentially determining intersection points of four edges of the cone-shaped view field and the earth.
9. The system for the computational analysis of the spatial synchronization rate of a formation SAR satellite according to claim 8, wherein said module M2.3 comprises:
module M2.3.1: according to the attitude guide angle and the edge view angles A1, A2, A3 and A4, obtaining an edge vector direction under an orbit coordinate system according to a specified turn sequence;
wherein A1 corresponds to the edge vector L1 O Obtained by the following formula:
where rotx, roty, rotz represents the corresponding transformation matrix rotated about the x, y, z axes, respectively.
A1 (2) represents a second element of the angle matrix A1; a1 (1) represents the first element of the angle matrix A1;
wherein A2 corresponds to the edge vector L2 O Obtained by the following formula:
a2 (2) represents a second element of the angle matrix A2; a2 (1) represents the first element of the angle matrix A2;
wherein A3 corresponds to the edge vector L3 O Obtained by the following formula:
a3 (2) represents a second element of the angle matrix A3; a3 (1) represents the first element of the angle matrix A3;
wherein A4 corresponds to the edge vector L4 O Obtained by the following formula:
a4 (2) represents a second element of the angle matrix A4; a4 (1) represents the first element of the angle matrix A4;
module M2.3.2: according to satellite position and speed and time information, converting to obtain a description of an edge vector direction under a ground-fixed coordinate system;
module M2.3.3: the earth is equivalent to an ellipsoid, and an ellipsoid equation is obtained by description in a geodetic coordinate system; determining a space straight line according to satellite position coordinates and the edge vector direction; converting the view field range solving problem into a space straight line and ellipsoid intersection point for solving;
module M2.3.4: after solving to obtain the position coordinates of the ellipsoidal intersection point of the space straight line and the ellipsoidal intersection point, converting the position coordinates into longitude and latitude descriptions, and respectively obtaining imaging areas of the longitude and latitude descriptions for the formation double stars.
10. The system for computational analysis of the space-time synchronization rate of a formation SAR satellite according to claim 6, further comprising:
module M4: and analyzing the overlapping rate of the imaging region after engineering errors are added.
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