Medium orbit satellite-oriented shipborne communication-in-motion antenna pointing error loss estimation method

Abstract

The invention discloses a medium-orbit satellite-oriented shipborne communication-in-motion antenna pointing error loss estimation method. The method comprises the following steps: importing STK analysis software based on two rows of elements of a medium-orbit satellite to obtain the height, longitude and latitude of a target satellite in a geocentric geodetic coordinate system; secondly, establishing an ellipsoid coordinate system based on the position information of the medium-orbit satellite, obtaining a position vector of the medium-orbit satellite in the ellipsoid coordinate system, and further obtaining an antenna position vector in a geographic coordinate system; converting the antenna position vector under the geographic coordinate system to a carrier coordinate system based on the attitude information rotating coordinate system of the ship to obtain the theoretical pitch angle and azimuth angle of the antenna under the carrier coordinate system of the ship; then, an encoder is installed in a ship-borne communication-in-motion antenna rotary table to obtain the actual pitch angle and azimuth angle of the antenna in a ship coordinate system, and finally, the antenna pointing error loss is obtained based on the antenna theoretical pointing angle and the actual pointing angle. The method has the characteristics of convenience in estimation and high accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite communication antennas, and in particular relates to a method for estimating pointing error loss of a shipborne in-motion communication antenna facing a medium-orbit satellite. Background Art

[0002] Satellite communications have the characteristics of wide coverage and strong resistance to natural disasters, and have great application prospects in remote areas and oceans. After the completion of the medium-orbit satellite communication constellation, it will realize personalized broadband network services with global coverage without blind spots, and can jointly build a unified space-ground 6G network with low-orbit satellite Internet and high-orbit satellite Internet, realizing access for all types of users in all scenarios and regions.

[0003] The satellite communication antenna on the ship carrier cannot accurately align with the satellite due to the two-way movement between the medium-orbit satellite and the ship, resulting in antenna deviation error loss, affecting the performance of the mobile communication system, and further leading to poor communication quality. The existing technology is mainly aimed at relatively static high-orbit satellites, without considering the movement of the satellite end, and the loss calculation for the vehicle-mounted mobile communication antenna. Its disadvantage is that it does not consider the change of attitude information and cannot be applied to ship scenarios.

[0004] In the prior art, the disclosed methods for estimating the pointing error loss of satellite in-motion antennas are as follows: Application No. CN202211245166.0, a method for measuring antenna loss, which measures the normalized carrier-to-noise ratio and antenna directivity of the antenna system in a microwave darkroom environment to calculate the antenna loss. However, this method cannot determine the position of the satellite end, does not further consider the antenna pointing error, and requires the construction of a microwave darkroom environment, which is not suitable for medium-orbit satellites. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for estimating the pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite. By using satellite ephemeris data and the position of the satellite, the problem of calculating the link loss of the shipborne in-motion antenna is solved.

[0006] Technical solution: A method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite of the present invention comprises the following steps:

[0007] S1. Two rows of Kepler roots based on medium-orbit satellites are imported into STK analysis software to obtain the altitude, longitude and latitude of the target satellite in the geocentric coordinate system;

[0008] S2. Establish an ellipsoidal coordinate system based on the position information of the medium-orbit satellite, obtain the position vector of the medium-orbit satellite in the ellipsoidal coordinate system, including the azimuth and elevation angle, and further obtain the antenna position vector in the geographic coordinate system;

[0009] S3, based on the attitude information of the ship, the coordinate system is rotated to convert the antenna position vector in the geographic coordinate system to the carrier coordinate system, and the theoretical pointing angle of the antenna in the ship carrier coordinate system is obtained;

[0010] S4. Install an encoder in the shipborne moving antenna turntable to obtain the actual pointing angle of the antenna in the ship coordinate system;

[0011] S5. Based on the theoretical pointing angle and the actual pointing angle of the antenna, the antenna pointing error loss is obtained.

[0012] Furthermore, step S1 specifically includes the following steps:

[0013] S11. Create a medium-orbit satellite simulation scene in the STK analysis software and set the scene parameters, including: simulation start time, simulation end time and simulation step size;

[0014] S12. Import satellite ephemeris data, create a target satellite, simulate the trajectory, obtain the instantaneous coordinates of each sampling time in the geocentric inertial coordinate system, and obtain the altitude, longitude, and latitude of the medium-orbit satellite.

[0015] Furthermore, step S2 specifically includes the following steps:

[0016] S21. Based on the altitude, longitude and latitude of the medium-orbit satellite in the geocentric inertial coordinate system, the position in the geocentric inertial coordinate system is converted into a projection in the geocentric inertial coordinate system to obtain the indexes for measuring the antenna pointing, namely the azimuth and pitch angles. The projection is calculated by the following formula:

[0017]

[0018] Where: x i ,y i ,z i is the projection of the medium-orbit satellite in the geocentric inertial coordinate system, θ i ,λ i , H are the latitude, longitude and altitude of the medium-orbit satellite in the geocentric inertial coordinate system, and R is the radius of the earth;

[0019] S22. After obtaining the projection of the medium-orbit satellite in the geocentric inertial coordinate system, in the geographic coordinate system, the azimuth and pitch angles of the medium-orbit satellite in the geographic coordinate system are obtained through the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection, and the conversion coordinate system.

[0020] Further, in step S22, the step of obtaining the azimuth and pitch angle of the medium-orbit satellite in the geographic coordinate system by the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection and the conversion coordinate system specifically includes the following steps:

[0021] S221, Earth-centered inertial coordinate systemi x i y i z i Around i x i Rotate λ counterclockwise to get coordinate system o i 'x i 'y i 'z i ';

[0022] S222, around o i 'z i 'Rotate θ counterclockwise to get coordinate system o i ”x i ”y i ”z i ”;

[0023] S223, in o i ”y i ” direction by translating the earth radius R, where λ,θ are the longitude and latitude of the moving antenna;

[0024] S224. According to the corresponding relationship between the antenna and the satellite related angles in the geographic coordinate system, the antenna position vector in the geographic coordinate system is obtained.

[0025] Furthermore, step S3 specifically includes the following steps:

[0026] S31, by converting the antenna pointing in the geographic coordinate system to the ship coordinate system, thereby compensating the ship attitude angle, that is, compensating the azimuth angle, pitch angle and roll angle; converting the antenna position vector in the geographic coordinate system to the carrier coordinate system by rotating the coordinate system;

[0027] S32, the geographic coordinate system o g x g y g z g Around oz g The axis rotates counterclockwise about the azimuth angle Y to obtain the ox1y1z1 coordinate system, and then rotates the pitch angle P clockwise around the ox1 coordinate system to obtain ox2y2z2, and then rotates the roll angle R clockwise around the oy2 axis to obtain ox b y b z b coordinate system, and finally get the antenna at ox b y b z b Theoretical azimuth and elevation angles in the coordinate system.

[0028] Furthermore, step S4 specifically includes the following steps:

[0029] S41, the moving antenna is fixed on the ship. In order to measure the actual direction of the antenna during the movement of the ship, a turntable is set in the antenna base, and a conductive slip ring is installed on the turntable to enable the azimuth axis to achieve 360° continuous rotation. The azimuth encoder and pitch encoder can measure the real-time pitch angle and azimuth angle of the antenna.

[0030] S42. Define the ship's horizontal coordinate system as a Cartesian coordinate system with the origin being the ship's center of gravity. The center of gravity is assumed to be parallel to the horizontal plane, the x-axis is horizontal to the ship's bow and stern line direction, the y-axis is parallel to the ship's transverse direction, the z-axis forms a right-handed coordinate system with the x-axis and the y-axis, and the positive direction is vertically upward. The ship's position information is obtained through the AIS system, and the ship's azimuth, pitch angle, and roll angle are obtained through the motion reference unit MRU. The Kalman filter modeling is integrated to infer the ship's attitude information at the next moment, and the actual pointing angle of the ship's onboard mobile communication antenna at each moment in the ship's horizontal coordinate system at a certain moment is obtained in combination with the ship information.

[0031] Furthermore, step S5 specifically includes the following steps:

[0032] S51. Combining the deviation angle of the azimuth angle and the deviation angle of the elevation angle of the shipborne antenna, vector superposition is performed on the azimuth angle and the elevation angle in the ship's horizontal coordinate system according to the parallelogram law, and the diagonal angle formed by the superposition is the antenna pointing deviation angle Δθ;

[0033] S52. When the electromagnetic field is uniformly distributed on the moving antenna, the antenna pointing error loss satisfies the Bessel function, and the antenna loss gain is calculated by the following formula:

[0034]

[0035] Where J1(u) is the first-order Bessel function of the first kind, D is the antenna aperture, and λ is w is the antenna operating wavelength.

[0036] The present invention also discloses a computer device, comprising a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method of the present invention.

[0037] The present invention also discloses a computer-readable storage medium on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, the steps of the method of the present invention are implemented.

[0038] The present invention also discloses a computer program product, comprising a computer program / instruction, which implements the steps of the method of the present invention when executed by a processor.

[0039] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0040] 1. The method of the present invention calculates antenna deviation error loss without the need for actual measurement of antenna radiation patterns, thereby improving calculation efficiency.

[0041] 2. The method of the present invention calculates the deviation error loss of the ship-borne moving communication antenna, takes into account the changes in the ship's position information and attitude information and the movement of the satellite end, and realizes the compensation of the angle information by converting the coordinate system, so that the calculation is accurate.

[0042] 3. The method of the present invention is suitable for calculating the deviation error loss of different types of parabolic antennas on ships and has good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0045] In order to achieve the above-mentioned purpose of the invention, Figure 1 It can be seen that the technical solution adopted by the present invention is: a method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite, comprising the following steps:

[0046] S1. Based on the two rows of Kepler roots of the medium-orbit satellite, the STK analysis software is imported to obtain the altitude, longitude and latitude of the target satellite in the geocentric coordinate system;

[0047] S2. Based on the position information of the medium-orbit satellite, considering that the earth is an ellipsoid, an ellipsoid coordinate system is established to obtain the position vector of the medium-orbit satellite in the ellipsoid coordinate system, including the azimuth and elevation angle, and further obtain the antenna position vector in the geographic coordinate system;

[0048] S3. According to the ship's attitude information, the antenna position vector in the geographic coordinate system is converted to the carrier coordinate system by rotating the coordinate system to obtain the theoretical elevation angle and azimuth angle of the antenna in the ship carrier coordinate system;

[0049] S4. Install an encoder in the ship-borne moving communication antenna turntable to obtain the actual pitch angle and azimuth angle of the antenna in the ship coordinate system;

[0050] S5. Calculate the antenna pointing error loss based on the pointing deviation angle.

[0051] Preferably, in step S1, two rows of Kepler roots based on medium-orbit satellites are imported into STK analysis software, and the specific method is as follows:

[0052] S11. Create a medium-orbit satellite simulation scene in the STK analysis software and set the scene parameters, including: simulation start time, simulation end time and simulation step size;

[0053] S12. Import satellite ephemeris data, create a target satellite, simulate the trajectory, obtain the instantaneous coordinates of each sampling time in the geocentric inertial coordinate system, and obtain the altitude, longitude, and latitude of the medium-orbit satellite.

[0054] Preferably, in step S2, an ellipsoid coordinate system is established based on the position information of the medium-orbit satellite to obtain the position vector of the medium-orbit satellite in the ellipsoid coordinate system, and the specific method is as follows:

[0055] S21. Based on the altitude, longitude and latitude of the medium-orbit satellite in the geocentric inertial coordinate system, the position in the geocentric inertial coordinate system is converted into a projection in the geocentric inertial coordinate system to obtain the indexes for measuring the antenna pointing, namely the azimuth and pitch angles. The projection is calculated by the following formula:

[0056]

[0057] Where: x i ,y i ,z i is the projection of the medium-orbit satellite in the geocentric inertial coordinate system, θ i ,λ i , H are the latitude, longitude and altitude of the medium-orbit satellite in the geocentric inertial coordinate system, and R is the radius of the earth;

[0058] S22. After obtaining the projection of the medium-orbit satellite in the geocentric inertial coordinate system, in the geographic coordinate system, the azimuth and pitch angles of the medium-orbit satellite in the geographic coordinate system are obtained through the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection, and the conversion coordinate system.

[0059] Further, in step S22, the step of obtaining the azimuth and pitch angle of the medium-orbit satellite in the geographic coordinate system by the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection and the conversion coordinate system specifically includes the following steps:

[0060] S221, Earth-centered inertial coordinate system i x i y i z i Around i x i Rotate λ counterclockwise to get coordinate system o i 'x i 'y i'z i ';

[0061] S222, around o i 'z i 'Rotate θ counterclockwise to get coordinate system o i ”x i ”y i ”z i ”;

[0062] S223, in o i ”y i ” direction by translating the earth radius R, where λ,θ are the longitude and latitude of the moving antenna;

[0063] S224. According to the corresponding relationship between the antenna and the satellite related angles in the geographic coordinate system, the antenna position vector in the geographic coordinate system is obtained.

[0064] Preferably, in step S3, the antenna position vector in the geographic coordinate system is converted to the carrier coordinate system by rotating the coordinate system based on the attitude information of the ship, and the specific method is as follows:

[0065] S31. In actual situations, the ship is constantly moving forward and changing. By converting the antenna pointing in the geographic coordinate system to the ship coordinate system, the ship attitude angle is compensated, that is, the azimuth, pitch angle and roll angle are compensated; the antenna position vector in the geographic coordinate system is converted to the carrier coordinate system by rotating the coordinate system;

[0066] S32, the geographic coordinate system o g x g y g z g Around oz g The axis rotates counterclockwise about the azimuth angle Y to obtain the ox1y1z1 coordinate system, and then rotates the pitch angle P clockwise around the ox1 coordinate system to obtain ox2y2z2, and then rotates the roll angle R clockwise around the oy2 axis to obtain ox b y b z b coordinate system, and finally get the antenna at ox b y b z b Theoretical azimuth and elevation angles in the coordinate system.

[0067] Preferably, in step S4, an encoder is installed in the shipborne moving communication antenna turntable to obtain the actual pitch angle and azimuth angle of the antenna in the ship coordinate system, and the specific method is:

[0068] S41, the moving antenna is fixed on the ship. In order to measure the actual direction of the antenna during the movement of the ship, a turntable is set in the antenna base, and a conductive slip ring is installed on the turntable to enable the azimuth axis to achieve 360° continuous rotation. The azimuth encoder and pitch encoder can measure the real-time pitch angle and azimuth angle of the antenna.

[0069] S42. Define the ship's horizontal coordinate system as a Cartesian coordinate system with the origin being the ship's center of gravity. The center of gravity is assumed to be parallel to the horizontal plane, the x-axis is horizontal to the ship's bow and stern line direction, the y-axis is parallel to the ship's transverse direction, the z-axis forms a right-handed coordinate system with the x-axis and the y-axis, and the positive direction is vertically upward. The ship's position information is obtained through the AIS system, and the ship's azimuth, pitch angle, and roll angle are obtained through the motion reference unit MRU. The Kalman filter modeling is integrated to infer the ship's attitude information at the next moment, and the actual pointing angle of the ship's onboard mobile communication antenna at each moment in the ship's horizontal coordinate system at a certain moment is obtained in combination with the ship information.

[0070] Preferably, in step S5, based on the theoretical pointing angle and the actual pointing angle of the antenna, the antenna pointing error loss is obtained in the following specific manner:

[0071] S51. Combining the deviation angle of the azimuth angle and the deviation angle of the elevation angle of the shipborne antenna, vector superposition is performed on the azimuth angle and the elevation angle in the ship's horizontal coordinate system according to the parallelogram law, and the diagonal angle formed by the superposition is the antenna pointing deviation angle Δθ;

[0072] S52. When the electromagnetic field is uniformly distributed on the moving antenna, the antenna pointing error loss satisfies the Bessel function, and the antenna loss gain is calculated by the following formula:

[0073]

[0074] Where J1(u) is the first-order Bessel function of the first kind, D is the antenna aperture, and λ is w is the antenna operating wavelength.

Claims

1. A method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite, characterized in that: The steps include: S1. Two rows of Kepler roots based on medium-orbit satellites are imported into STK analysis software to obtain the altitude, longitude and latitude of the target satellite in the geocentric coordinate system; S2. Establish an ellipsoidal coordinate system based on the position information of the medium-orbit satellite, obtain the position vector of the medium-orbit satellite in the ellipsoidal coordinate system, including the azimuth and elevation angle, and further obtain the antenna position vector in the geographic coordinate system; S3, based on the attitude information of the ship, the coordinate system is rotated to convert the antenna position vector in the geographic coordinate system to the carrier coordinate system, and the theoretical pointing angle of the antenna in the ship carrier coordinate system is obtained; S4. Install an encoder in the shipborne moving antenna turntable to obtain the actual pointing angle of the antenna in the ship coordinate system; S5. Based on the theoretical pointing angle and the actual pointing angle of the antenna, the antenna pointing error loss is obtained.

2. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11. Create a medium-orbit satellite simulation scene in the STK analysis software and set the scene parameters, including: simulation start time, simulation end time and simulation step size; S12. Import satellite ephemeris data, create a target satellite, simulate the trajectory, obtain the instantaneous coordinates of each sampling time in the geocentric inertial coordinate system, and obtain the altitude, longitude, and latitude of the medium-orbit satellite.

3. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21. Based on the altitude, longitude and latitude of the medium-orbit satellite in the geocentric inertial coordinate system, the position in the geocentric inertial coordinate system is converted into a projection in the geocentric inertial coordinate system to obtain the indexes for measuring the antenna pointing, namely the azimuth and pitch angles. The projection is calculated by the following formula: Where: x i ,y i ,z i is the projection of the medium-orbit satellite in the geocentric inertial coordinate system, θ i ,λ i , H are the latitude, longitude and altitude of the medium-orbit satellite in the geocentric inertial coordinate system, and R is the radius of the earth; S22. After obtaining the projection of the medium-orbit satellite in the geocentric inertial coordinate system, in the geographic coordinate system, the azimuth and pitch angles of the medium-orbit satellite in the geographic coordinate system are obtained through the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection, and the conversion coordinate system.

4. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 3, characterized in that: In step S22, the step of obtaining the azimuth and pitch angle of the medium-orbit satellite in the geographic coordinate system by the relationship between the pitch angle and azimuth of the medium-orbit satellite and the projection and the conversion coordinate system specifically includes the following steps: S221, Earth-centered inertial coordinate system i x i y i z i Around i x i Rotate λ counterclockwise to get coordinate system o i 'x i 'y i 'z i '; S222, around o i 'z i 'Rotate θ counterclockwise to get coordinate system o i ”x i "y i ”z i ”; S223, in o i ”y i ” direction by translating the earth radius R, where λ,θ are the longitude and latitude of the moving antenna; S224. According to the corresponding relationship between the antenna and the satellite related angles in the geographic coordinate system, the antenna position vector in the geographic coordinate system is obtained.

5. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31, by converting the antenna pointing in the geographic coordinate system to the ship coordinate system, thereby compensating the ship attitude angle, that is, compensating the azimuth angle, pitch angle and roll angle; converting the antenna position vector in the geographic coordinate system to the carrier coordinate system by rotating the coordinate system; S32, the geographic coordinate system o g x g y g z g Around oz g The axis rotates counterclockwise about the azimuth angle Y to obtain the ox1y1z1 coordinate system, and then rotates the pitch angle P clockwise around the ox1 coordinate system to obtain ox2y2z2, and then rotates the roll angle R clockwise around the oy2 axis to obtain ox b y b z b coordinate system, and finally get the antenna at ox b y b z b Theoretical azimuth and elevation angles in the coordinate system.

6. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 1, characterized in that: Step S4 specifically includes the following steps: S41, the moving antenna is fixed on the ship. In order to measure the actual direction of the antenna during the movement of the ship, a turntable is set in the antenna base, and a conductive slip ring is installed on the turntable to enable the azimuth axis to achieve 360° continuous rotation. The azimuth encoder and pitch encoder can measure the real-time pitch angle and azimuth angle of the antenna. S42. Define the ship's horizontal coordinate system as a Cartesian coordinate system with the origin being the ship's center of gravity. The center of gravity is assumed to be parallel to the horizontal plane, the x-axis is horizontal to the ship's bow and stern line direction, the y-axis is parallel to the ship's transverse direction, the z-axis forms a right-handed coordinate system with the x-axis and the y-axis, and the positive direction is vertically upward. The ship's position information is obtained through the AIS system, and the ship's azimuth, pitch angle, and roll angle are obtained through the motion reference unit MRU. The Kalman filter modeling is integrated to infer the ship's attitude information at the next moment, and the actual pointing angle of the ship's onboard mobile communication antenna at each moment in the ship's horizontal coordinate system at a certain moment is obtained in combination with the ship information.

7. The method for estimating pointing error loss of a shipborne in-motion antenna facing a medium-orbit satellite according to claim 1, characterized in that: Step S5 specifically includes the following steps: S51. Combining the deviation angle of the azimuth angle and the deviation angle of the elevation angle of the shipborne antenna, vector superposition is performed on the azimuth angle and the elevation angle in the ship's horizontal coordinate system according to the parallelogram law, and the diagonal angle formed by the superposition is the antenna pointing deviation angle Δθ; S52. When the electromagnetic field is uniformly distributed on the moving antenna, the antenna pointing error loss satisfies the Bessel function, and the antenna loss gain is calculated by the following formula: Where J1(u) is the first-order Bessel function of the first kind, D is the antenna aperture, and λ is w is the antenna operating wavelength.

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method of claim 1.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

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