An azimuth-elevation type two-axis antenna high-elevation over-the-top pointing deviation algorithm

Abstract

This invention discloses an algorithm for high elevation angle over-the-top pointing deviation of an azimuth-elevation two-axis antenna, specifically including the following steps: Step 1, obtaining the theoretical position information P1 of the spacecraft relative to the ground station; Step 2, determining the actual pointing position information P2 of the antenna; Step 3, the ground station calculates the deviation δ between the theoretical angle of the spacecraft at the same moment within the tracking arc and the actual pointing angle of the antenna obtained in Step 2, based on the theoretical position information of the spacecraft obtained in Step 1 and the actual pointing position information of the antenna determined in Step 2; Step 4, comparing the angle deviation δ obtained in Step 3 with the antenna beamwidth ψ to determine whether the antenna high elevation angle over-the-top angle deviation meets the spacecraft tracking requirements. Using this invention, when tracking a spacecraft with an azimuth-elevation two-axis antenna, it is possible to accurately determine whether the antenna high elevation angle over-the-top angle deviation meets the spacecraft tracking requirements.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft measurement and control technology, and relates to an algorithm for high elevation angle over-the-top pointing deviation of an azimuth-elevation type two-axis antenna. Background Technology

[0002] Azimuth-elevation biaxial antennas are widely used in aerospace telemetry, tracking, and payload data reception due to their simple structure, low transmission error, and high pointing accuracy. However, because azimuth-elevation antennas are limited by the maximum angular velocities of their azimuth and elevation axes, they may not be able to meet the spacecraft tracking requirements during high-elevation overhead maneuvers. To provide a scientific basis for spacecraft flight procedure development and ensure the transmission of critical spacecraft commands and the reception of critical telemetry and payload data, it is necessary to accurately determine whether the antenna meets the spacecraft tracking requirements during high-elevation periods. Summary of the Invention

[0003] The purpose of this invention is to provide an algorithm for high elevation angle over-the-top pointing deviation of an azimuth-elevation two-axis antenna. This algorithm can accurately determine whether the high elevation angle over-the-top angle deviation of the antenna meets the spacecraft tracking requirements when the azimuth-elevation two-axis antenna is tracking a spacecraft.

[0004] The technical solution adopted in this invention is an algorithm for high elevation angle over-the-top pointing deviation of an azimuth-elevation type two-axis antenna, which specifically includes the following steps:

[0005] Step 1: Obtain the theoretical position information P1(R1,A1,E1) of the spacecraft relative to the ground station;

[0006] Step 2: Determine the actual pointing position information of the antenna, P2(R2,A2,E2);

[0007] Step 3: Based on the spacecraft's theoretical position information (R1, A1, E1) obtained in Step 1, and combined with the antenna's actual pointing position information (R2, A2, E2) determined in Step 2, the ground station calculates the deviation δ between the spacecraft's theoretical angle and the antenna's actual pointing angle obtained in Step 2 at the same moment within the tracking arc.

[0008] Step 4: Compare the angle deviation δ obtained in Step 3 with the antenna beamwidth ψ to determine whether the antenna elevation angle over-the-top angle deviation meets the spacecraft tracking requirements.

[0009] The invention is further characterized by:

[0010] In step 1, the ground tracking and prediction method is used to obtain the theoretical position information P1(R1,A1,E1) of the spacecraft relative to the ground station, where R1, A1, and E1 are the theoretical radial distance, theoretical azimuth, and theoretical pitch angle of the spacecraft, respectively.

[0011] In step 2, the ground station antenna is set to digital guidance mode. The digital guidance source input is the theoretical azimuth angle A1 and elevation angle E1 of the spacecraft relative to the ground station. The antenna follows the theoretical trajectory of the spacecraft and outputs the actual azimuth angle A2 and elevation angle E2 of the antenna. If the radial distance of the spacecraft at this time is R2, then the actual pointing position information of the antenna is P2(R2,A2,E2).

[0012] The specific process of step 3 is as follows:

[0013] Step 3.1: Based on the theoretical position information (R1, A1, E1) of the spacecraft tracked by the antenna obtained in Step 1, which is the ground station's horizontal polar coordinate, the coordinate transformation is performed using formula (1) to obtain the ground station's horizontal rectangular coordinate (X1, Y1, Z1):

[0014]

[0015] Step 3.2: Based on the actual antenna pointing position information (R2, A2, E2) obtained in Step 2, which is the ground station's horizontal polar coordinates, the ground station's horizontal rectangular coordinates (X2, Y2, Z2) are obtained through spatial coordinate transformation using formula (2):

[0016]

[0017] Step 3.3, calculate the deviation δ between the theoretical angle of the antenna tracking the spacecraft and the actual pointing angle of the antenna at the same moment within the tracking arc according to formula (3):

[0018]

[0019] Step 3.4, Substitute formulas (1) and (2) into formula (3) to get: δ=arccos(cos E1 cos A1 cos E2 cosA2+sin E1 sin E2+cosE1 sin A1 cos E2 sin A2) (4).

[0020] The specific process of step 4 is as follows:

[0021] When δ≤ψ / 2, the spacecraft is within the antenna beam coverage area, which meets the spacecraft tracking requirements, and the antenna is able to track the target.

[0022] When δ>ψ / 2, the spacecraft is outside the antenna beam coverage area, which does not meet the spacecraft tracking requirements, and the antenna cannot track the target.

[0023] The beneficial effect of this invention is that by utilizing spacecraft trajectory information and ground station antenna position information, and by calculating the angle difference between the theoretical position information of the ground station tracking the spacecraft and the actual pointing position information of the antenna, combined with the antenna beamwidth, it can accurately determine whether the high elevation angle of the azimuth-elevation type two-axis antenna meets the spacecraft tracking requirements. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the calculation method used in the algorithm for the high elevation angle over-the-top angle deviation of an azimuth-elevation type two-axis antenna according to the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] This invention provides an algorithm for high elevation angle over-the-top pointing deviation of an azimuth-elevation two-axis antenna, which specifically includes the following steps:

[0027] Step 1: Input the spacecraft's theoretical trajectory information and the location information of the ground station antenna (including longitude, latitude, and elevation). Use a ground tracking and prediction method to obtain the spacecraft's theoretical position information P1(R1,A1,E1) relative to the ground station. For example... Figure 1 Point P1 is shown in the diagram, where R1, A1, and E1 represent the spacecraft's theoretical radial distance, azimuth angle, and pitch angle, respectively. Figure 1 In the diagram, point O is the center of the antenna's three axes, point P1 is the theoretical position of the spacecraft, point P2 is the actual pointing position of the antenna, P'1 is the projection of P1 onto the XOZ plane, and P'2 is the projection of P2 onto the XOZ plane.

[0028] Step 2: The ground station antenna is set to digital guidance mode. The digital guidance source input is the theoretical azimuth and elevation angles (A1, E1) of the spacecraft relative to the ground station. The antenna follows the theoretical trajectory of the spacecraft and outputs the actual azimuth and elevation angles (A2, E2). Let the radial distance of the spacecraft at this time be R2, then the actual pointing position information of the antenna is P2(R2, A2, E2); Figure 1 Point P2 is shown in the diagram;

[0029] Step 3: Based on the spacecraft's theoretical position information (R1, A1, E1) input in Step 1, and combined with the antenna's actual pointing position information (R2, A2, E2) determined in Step 2, the ground station calculates the deviation δ between the spacecraft's theoretical angle at the same moment within the tracking arc and the antenna's actual pointing angle obtained in Step 2.

[0030] Step 3 is as follows:

[0031] Step 3.1: Based on the theoretical position information (R1, A1, E1) of the spacecraft tracked by the antenna obtained in Step 1, which is the ground station's horizontal polar coordinate, the coordinate transformation is performed using formula (1) to obtain the ground station's horizontal rectangular coordinate (X1, Y1, Z1):

[0032]

[0033] Step 3.2: Based on the actual antenna pointing position information (R2, A2, E2) obtained in Step 2, which is the ground station's horizontal polar coordinates, the ground station's horizontal rectangular coordinates (X2, Y2, Z2) are obtained through spatial coordinate transformation using formula (2):

[0034]

[0035] Where R1 = R2 = 1;

[0036] Step 3.3, calculate the deviation δ between the theoretical angle of the antenna tracking the spacecraft and the actual pointing angle of the antenna at the same moment within the tracking arc according to formula (3):

[0037]

[0038] In this context, * represents a multiplication relationship.

[0039] Step 3.4, substituting formulas (1) and (2) into formula (3), and further simplifying, we get:

[0040] δ=arccos(cos E1 cos A1 cos E2 cos A2 +sin E1 sin E2+cos E1 sin A1 cosE2 sinA2)(4);

[0041] Step 4: Compare the angle deviation δ obtained in Step 3 with the antenna beamwidth ψ to determine whether the antenna elevation angle over-the-top angle deviation meets the spacecraft tracking requirements.

[0042] The specific steps of step 4 are as follows:

[0043] Comparing the angle deviation δ obtained in step 3.4 with the antenna beamwidth ψ, when δ ≤ ψ / 2, the spacecraft is within the antenna beam coverage area, meeting the spacecraft tracking requirements, and the antenna can track the target; when δ > ψ / 2, the spacecraft is outside the antenna beam coverage area, not meeting the spacecraft tracking requirements, and the antenna cannot track the target. Therefore, it is possible to accurately determine whether the antenna elevation angle over-the-top angle deviation meets the spacecraft tracking requirements.

Claims

1. An azimuth-elevation type two-axis antenna high elevation over-the-horizon pointing deviation algorithm, characterized by: Specifically comprising the following steps: Step 1, obtaining the theoretical position information P1(R1, A1, E1) of the spacecraft relative to the ground station; In the step 1, the ground tracking prediction method is used to obtain the theoretical position information P1(R1, A1, E1) of the spacecraft relative to the ground station, wherein R1, A1 and E1 are the theoretical radial distance of the spacecraft, the theoretical azimuth angle of the spacecraft and the theoretical elevation angle of the spacecraft respectively; Step 2, determining the actual pointing position information P2(R2, A2, E2) of the antenna; in the step 2, the ground station antenna is set to a digital guidance working mode, the digital guidance source input is the theoretical azimuth angle A1 and the elevation angle E1 of the spacecraft relative to the ground station, the antenna follows the spacecraft theoretical trajectory number and outputs the actual pointing azimuth angle A2 and the elevation angle E2 of the antenna, and the radial distance of the spacecraft at this time is R2, so the actual pointing position information P2(R2, A2, E2) of the antenna is determined; Step 3, the ground station calculates the deviation δ between the theoretical angle of the spacecraft at the same time in the tracking arc segment and the actual pointing angle of the antenna obtained in step 2 according to the theoretical position information (R1, A1, E1) of the spacecraft obtained in step 1 and the actual pointing position information (R2, A2, E2) of the antenna determined in step 2; the specific process of the step 3 is as follows: Step 3.1, the antenna tracking spacecraft theoretical position information P1(R1, A1, E1) obtained in step 1 is the ground station ground polar coordinate, and the ground station ground rectangular coordinate (X1, Y1, Z1) is obtained through coordinate conversion by formula (1): （1）； Step 3.2, the actual pointing position information P2(R2, A2, E2) of the antenna obtained in step 2 is the ground station ground polar coordinate, and the ground station ground rectangular coordinate (X2, Y2, Z2) is obtained through space coordinate conversion by formula (2): （2）； Step 3.3, the deviation δ between the antenna tracking spacecraft theoretical angle and the actual pointing angle of the antenna at the same time in the tracking arc segment is calculated according to formula (3): （3）； Step 3.4, formula (1) and (2) are substituted into formula (3), and the following formula is obtained: （4）； Step 4, comparing the angle deviation δ obtained in step 3 with the antenna beam width ψ to determine whether the angle deviation of the antenna high elevation over-the-top angle meets the spacecraft tracking requirements; the specific process of the step 4 is as follows: When δ≤ψ / 2, the spacecraft is in the coverage range of the antenna beam, which meets the spacecraft tracking requirements, and the antenna can track the target; When δ>ψ / 2, the spacecraft is out of the coverage range of the antenna beam, which does not meet the spacecraft tracking requirements, and the antenna cannot track the target.

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