A method for antenna non-reversal tracking of LEO satellites from an earth station

Abstract

This invention discloses a non-reversing antenna tracking method for observing LEO satellites from an earth station, comprising: modifying the azimuth angle rotation range of the ground control station's azimuth-elevation mount antenna from 0–360° to ±270° with a zero-crossing switch, thus obtaining the modified control station antenna; calculating the theoretical antenna guidance angle at each moment when the control station tracks and observes the LEO satellite based on its position information and the satellite's orbit; dividing the original antenna azimuth angle rotation range into four equal intervals; correcting the intervals that meet the modification conditions according to the different situations of the starting and ending angles of the tracking in the theoretical azimuth guidance angle, thus obtaining the actual antenna guidance angle at each moment; generating an antenna guidance file according to a preset format; and driving the modified control station antenna to rotate accordingly by loading the antenna guidance file, thereby enabling uninterrupted tracking and observation of the LEO satellite during its transit. This invention can increase the effective observation time of the satellite by the ground control station.

Description

Technical Field

[0001] This invention belongs to the field of LEO satellite telemetry and control, specifically relating to a method for antenna non-reversal tracking of LEO satellites observed by an earth station. Background Technology

[0002] Positioning, navigation, and timing (PNT) technology is an indispensable and crucial technological support for national economic development and has become one of the important strategic development directions for the country's future. On July 31, 2020, the BeiDou-3 Global Navigation Satellite System (BDS) was officially launched, which is of great significance for achieving my country's independence and anti-interference capabilities in the PNT field. Unlike the medium and high orbit satellites of GNSS (Global Navigation Satellite System), low Earth orbit (LEO) satellites have advantages such as shorter development cycles, a larger number of satellites, stronger signal landing power, and faster satellite motion speeds. Using LEO satellite constellations to enhance traditional satellite PNT services has become a current research hotspot. Leveraging the advantages of LEO enhancement systems to overcome the bottlenecks of limited field of view, weak signal strength, and complex multipath effects in complex environments, thereby improving positioning accuracy and integrity, is an important research area for my country's future comprehensive PNT system transitioning from traditional GNSS to LEO enhancement.

[0003] In recent years, the rapid development of commercial low-Earth orbit (LEO) communication systems has led to the construction or ongoing development of LEO satellite constellations worldwide. Examples include the US's next-generation Iridium LEO system, SpaceX's Starlink, the UK's OneWeb constellation, and Telesat's Lightspeed constellation. Meanwhile, several domestic institutions are actively conducting theoretical research, simulation calculations, and on-orbit satellite verification related to LEO satellite enhancement, and have proposed corresponding constellation plans, accumulating experimental data for LEO satellite navigation signal enhancement and accuracy improvement technologies. Large LEO satellite constellations will effectively enhance satellite visibility for ground users, improve measurement geometry, and reduce multipath noise, which is of great significance for ground users in complex environments.

[0004] As LEO satellite constellation systems become the mainstream trend, the demand for telemetry, tracking, and command (TT&C) of low-Earth orbit (LEO) satellites is increasing daily. On-orbit TT&C management of LEO satellite constellations requires monitoring and emergency response throughout their entire lifecycle, from launch and orbit insertion, on-orbit testing, long-term satellite management, and deorbit handling. The LEO satellite TT&C system is fundamentally similar to the ground TT&C system of traditional geostationary orbit (GEO) satellites in terms of signal transmission links, both including antenna feed systems, antenna structure subsystems, antenna monitoring subsystems, radio frequency channel subsystems, integrated baseband subsystems, and ground TT&C and monitoring subsystems. Unlike high-Earth orbit (GEO) satellites, LEO satellites have shorter orbital periods, higher orbital speeds, and are not visible to ground TT&C stations in real time. Therefore, the TT&C management methods for LEO satellites differ significantly from those for GEO satellites, with TT&C and operation management being the most significant difference between the two systems.

[0005] Because ground-based observation stations are visible to geostationary orbit satellites all day, telemetry signals are also visible in real-time throughout the day. This means that ground-based observation stations can send uplink commands to geostationary orbit satellites at any time, offering good real-time performance. However, LEO satellites orbit approximately 14-15 times per day, with a single ground control station visible for 3-6 orbits, and each orbit's visibility time is only a few minutes at most. Given the high orbital speed of LEO satellites and the short visibility time for ground stations during satellite transits, the antennas at ground control stations should possess strong tracking and high-speed rotation capabilities. Most existing azimuth-elevation mount antennas have an azimuth rotation range of 0-360° and an elevation rotation range of 0-90°, and these antennas possess the ability to eliminate blind spots during satellite transits and to quickly acquire and track satellites at low elevation angles.

[0006] However, when the azimuth-elevation mount antenna of the ground control station has an azimuth angle rotation range of 0–360°, there is a transition in the ground antenna's azimuth guidance angle when a LEO satellite passes overhead, rotating from 360° clockwise to 0° or from 0° counterclockwise to 360°. When this occurs, due to the mechanical limitations of the azimuth-elevation mount antenna, the antenna must rotate 360° in both cases to continue observation. During satellite tracking at the ground control station, this antenna rotation will cause telemetry signal loss, forcing an interruption of information transmission and reducing the effective observation time of the ground control station when the satellite passes overhead. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, this invention provides a method for antenna-free tracking of LEO satellites from an earth station.

[0008] A method for antenna-free tracking of LEO satellites observed from an earth station includes:

[0009] The azimuth angle rotation range of the ground telemetry and control station's azimuth-elevation type mount antenna was modified from 0 to 360° to ±270° with a zero-crossing switch, resulting in the modified telemetry and control station antenna.

[0010] Based on the position information of the modified telemetry and control station antenna and the satellite's orbit, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated. The theoretical antenna guidance angle at any moment includes the theoretical antenna azimuth guidance angle and the theoretical antenna elevation guidance angle.

[0011] The original antenna azimuth angle rotation range is divided into 4 intervals. Based on the different situations of the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the modified telemetry and control station antenna when the satellite passes over, the theoretical azimuth guidance angle of the antenna that meets the modification conditions is corrected, so as to obtain the actual guidance angle of the antenna at each moment.

[0012] The actual antenna guidance angle at each moment is used to generate an antenna guidance file according to a preset format;

[0013] By loading the antenna guidance file, the modified telemetry and control station antenna is driven to rotate according to the actual antenna guidance angle in the antenna guidance file, thereby enabling uninterrupted tracking and observation of LEO satellites when they pass overhead.

[0014] In one embodiment of the present invention, the azimuth angle rotation range of the azimuth-elevation type mount antenna of the ground telemetry and control station is modified from 0 to 360° to ±270° with a zero-crossing switch, resulting in the modified telemetry and control station antenna, comprising:

[0015] By installing a preset azimuth limiting device on the azimuth-elevation type mount antenna of the ground control station, the azimuth angle rotation range of the azimuth-elevation type mount antenna of the ground control station is modified from 0 to 360° to ±270° with a zero-crossing switch, thus obtaining the modified control station antenna; wherein, the preset azimuth limiting device includes a stop block installed on the azimuth column of the azimuth-elevation type mount antenna of the ground control station, and a micro switch installed on the azimuth turntable.

[0016] In one embodiment of the present invention, based on the position information of the modified telemetry and control station antenna and the satellite's orbit, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated, including:

[0017] Using the two orbital elements of the LEO satellite and the station coordinates of the modified telemetry and control station antenna, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated according to the azimuth angle and elevation angle algorithm.

[0018] In one embodiment of the present invention, the original antenna azimuth angle rotation range is divided into four equal intervals, including:

[0019] Divide the 360° azimuth rotation range into four equal sections along the clockwise direction: the first section, the second section, the third section, and the fourth section.

[0020] In one embodiment of the present invention, the step of correcting the theoretical azimuth guidance angle of the antenna that meets the modification conditions based on the different situations in the intervals of the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the modified telemetry and control station antenna during satellite transit includes:

[0021] Based on the range of the starting and ending angles of the theoretical azimuth guidance angle of the modified telemetry and control station antenna during satellite transit, the theoretical azimuth guidance angle of the antenna is adjusted accordingly for cases that meet the modification conditions, such as crossing one interval, crossing two intervals, and crossing three intervals.

[0022] In one embodiment of the present invention, for cases that cross an interval and meet the modification conditions, the theoretical azimuth guidance angle of the antenna is corrected accordingly, including:

[0023] For cases where the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the antenna are both in the fourth interval and meet the modification conditions, and the tracking crosses one interval, the portion of the theoretical azimuth guidance angle of the antenna exceeding 270° will be reduced by 360°.

[0024] In one embodiment of the present invention, for cases that cross two intervals and meet the modification conditions, the theoretical azimuth guidance angle of the antenna is corrected accordingly, including:

[0025] For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the third interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°.

[0026] For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the third interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°.

[0027] For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°.

[0028] For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°.

[0029] In one embodiment of the present invention, for cases that meet the modification conditions and span three intervals, the theoretical azimuth guidance angle of the antenna is corrected accordingly, including:

[0030] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the second interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°.

[0031] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°.

[0032] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the third interval, and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°.

[0033] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the third interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°.

[0034] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 270° will be reduced by 360°.

[0035] For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle is in the second interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle exceeding 270° will be reduced by 360°.

[0036] In one embodiment of the present invention, driving the modified telemetry and control station antenna to rotate according to the actual antenna guidance angle in the antenna guidance file by loading the antenna guidance file includes:

[0037] The antenna guidance file is automatically loaded and driven by the ACU so that the modified telemetry and control station antenna rotates according to the actual antenna guidance angle at each moment in the antenna guidance file.

[0038] The beneficial effects of this invention are:

[0039] The solution provided in this invention enables uninterrupted tracking of LEO satellites by ground control stations during their transit, completely resolving the problem of forced interruption of uplink and downlink information transmission between the ground control station and the satellite due to the reversal of the azimuth-elevation mount antenna of the ground control station. This allows the ground control station antenna to continuously complete uplink and downlink information transmission between the satellite and the ground control station during LEO satellite transit, increasing the effective observation time of the satellite by the ground control station and making the LEO satellite constellation tracking, control, and management more flexible and controllable, thus possessing significant engineering practical value. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating a method for antenna-free tracking of LEO satellites observed by an earth station, provided in an embodiment of the present invention.

[0041] Figure 2 A schematic diagram illustrating the process of an antenna-free tracking method for observing LEO satellites from an earth station, as provided in an embodiment of the present invention.

[0042] Figures 3a-3c This is a schematic diagram of the relevant structure of the modified telemetry and control station antenna in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the satellite in a Cartesian coordinate system at the station center;

[0044] Figure 5 This is a schematic diagram of the antenna azimuth angle rotation range in an embodiment of the present invention. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0046] To maximize the visible arc of the LEO constellation telemetry, tracking, and command (TT&C) system for satellites and completely resolve the data interruption caused by the reversal of azimuth-elevation mount antennas at ground control stations, enabling uninterrupted uplink and downlink information transmission between the satellite and the ground control station during LEO satellite transits, this invention proposes a reversal-free antenna tracking method for LEO satellite observation from earth stations, based on the characteristics of LEO constellation TT&C management. This method is applicable to ground antenna observation when using a ring-focus dual-reflector antenna with an azimuth-elevation mount to perform LEO constellation TT&C tasks. Please refer to [link to relevant documentation]. Figure 1 and Figure 2 As shown, the method may include the following steps S1 to S5:

[0047] S1, modify the azimuth angle rotation range of the ground telemetry and control station azimuth-elevation type mount antenna from 0 to 360° to ±270° with zero-crossing switch, and obtain the modified telemetry and control station antenna;

[0048] For the currently used azimuth-elevation mount antenna of the ground control station, the azimuth rotation range can be modified by only changing some small structural components. Specifically, by installing a preset azimuth limiting device on the azimuth-elevation mount antenna of the ground control station, the azimuth rotation range of the azimuth-elevation mount antenna of the ground control station is modified from 0 to 360° to ±270° with a zero-crossing switch, resulting in the modified control station antenna. The preset azimuth limiting device includes a stop block installed on the azimuth column of the azimuth-elevation mount antenna of the ground control station, and a micro switch installed on the azimuth turntable.

[0049] Please see Figures 3a-3c Understand the modification of the antenna structure at the telemetry and control station. Among them, Figure 3b and Figure 3c These are schematic diagrams of the modified telemetry and control station antenna from different angles. Figure 3a This is a magnified view of a portion of the image.

[0050] See details Figure 3a The toggle block is located in the middle position of the zero-crossing switch, which is the orientation zero position. The stop blocks include forward limit stop blocks and reverse limit stop blocks, and the micro switch includes forward limit switch and reverse limit switch.

[0051] When the intermediate shaft rotates clockwise, the toggle block disengages from the zero-crossing switch, and at the same time, the zero-crossing switch feeds back a clockwise signal to the servo system (reverse limit state isolation). After rotating 270°, the clockwise limit block touches the clockwise limit switch, and the antenna stops rotating.

[0052] Similarly, when the intermediate shaft rotates counterclockwise, the toggle block disengages from the zero-crossing switch, and at the same time, the zero-crossing switch feeds back a reverse signal to the servo system (forward limit state isolation). After rotating 270°, the reverse limit block touches the reverse limit switch, and the antenna stops rotating.

[0053] At this point, the antenna can rotate within a range of ±270°.

[0054] Through the above modifications, the actual effective rotation range of the telemetry and control station antenna azimuth angle can be changed to 540°.

[0055] S2, based on the position information of the modified telemetry and control station antenna and the satellite's orbit, calculate the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite. The theoretical antenna guidance angle at any moment includes the theoretical antenna azimuth guidance angle and the theoretical antenna elevation guidance angle.

[0056] Based on the position information of the modified telemetry and control station antenna and the satellite's orbit, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated, including:

[0057] Using the two orbital elements (TLE) of the LEO satellite and the station coordinates of the modified tracking and control station antenna, the theoretical antenna guidance angle at each moment when the tracking and control station tracks and observes the LEO satellite is calculated according to the azimuth angle and elevation angle algorithm.

[0058] The above process can be found in relevant technical explanations, and will not be described in detail here.

[0059] It is understandable that the theoretical antenna guidance angle is the theoretical angle used to guide the antenna's angular rotation. For a full 24 hours, the corresponding theoretical antenna guidance angle is calculated every second, including a theoretical azimuth guidance angle and a theoretical elevation guidance angle.

[0060] S3, the original antenna azimuth angle rotation range is divided into 4 intervals; based on the different situations of the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the modified telemetry and control station antenna when the satellite passes over, the theoretical azimuth guidance angle of the antenna that meets the modification conditions is corrected, so as to obtain the actual guidance angle of the antenna at each moment.

[0061] Those skilled in the art will understand that calculating the azimuth and elevation angles of a target satellite when observing it from a ground station antenna typically requires three coordinate transformations to obtain the satellite's coordinates (x, y, y) in the station-centered horizontal coordinate system. s ,y s ,z s Then, based on the satellite coordinates, the observation angle of the ground station antenna relative to the satellite can be calculated. The method for calculating the observation angle is as follows:

[0062]

[0063] Where Az is the azimuth angle; El is the elevation angle; Figure 4 This is a schematic diagram of the satellite in a Cartesian coordinate system centered at the station. In the tangent plane of the station-centered horizontal coordinate system, the satellite crosses the tangent plane twice, once during its entry and once during its exit, at which point the elevation angle observed by the ground station is ≥0°. In the extreme case of the satellite's entry and exit arcs, let z... s=0, at which point the elevation angle observed by the ground station is 0°, and the azimuth arc segment observed by the ground station is the longest. From equation (1), we know:

[0064]

[0065] Among them, Az u and Az d These are the two azimuth angles corresponding to the longest azimuth arc segment observed by the ground station.

[0066] According to equations (3) and (4), the maximum arc segment of the ground station antenna azimuth angle when the satellite enters or leaves the country is as follows:

[0067]

[0068] According to the range of the arctangent function Combining equation (5), the range of the maximum arc segment of the ground station azimuth angle can be obtained as follows:

[0069]

[0070] As can be seen from equation (6), the maximum azimuth angle rotation range of the ground station antenna when observing satellites is 180°.

[0071] Based on this, the present invention proposes a guidance angle correction method for ground station antenna non-reversal tracking.

[0072] like Figure 5 As shown, firstly, the original antenna azimuth rotation range is divided into 4 equal intervals, specifically:

[0073] Divide the 360° azimuth rotation range into four equal sections along the clockwise direction: the first section, the second section, the third section, and the fourth section.

[0074] It is understandable that due north is the 0° direction. Following the above processing, the rotation range of 0° to 360° is divided into four equal intervals, which are denoted by ①②③④ for ease of understanding. See also... Figure 5 It can be seen that each interval corresponds to an azimuth range.

[0075] Then, based on the different situations of the starting and ending angles in the theoretical azimuth guidance angles of the modified telemetry and control station antennas during satellite transit, the theoretical azimuth guidance angles of the antennas that meet the modification conditions are corrected. This part specifically includes:

[0076] Based on the range of the starting and ending angles of the theoretical azimuth guidance angle of the modified telemetry and control station antenna during satellite transit, the theoretical azimuth guidance angle of the antenna is adjusted accordingly for cases that meet the modification conditions, such as crossing one interval, crossing two intervals, and crossing three intervals.

[0077] In this embodiment of the invention, based on the different starting and ending angles of the tracking antenna of the telemetry and control station when each satellite passes overhead, three cases can be discussed separately: 1) crossing one interval; 2) crossing two intervals; 3) crossing three intervals. The following discussion only involves the cases that need modification. The other cases can be observed normally by default after the azimuth angle rotation range is changed from 0 to 360° to ±270°, and no further modifications are required.

[0078] (a) Cases involving crossing a single interval:

[0079] For cases that cross a certain interval and meet the modification conditions, the corresponding theoretical azimuth guidance angle of the antenna should be adjusted, including:

[0080] For cases where the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the antenna are both in the fourth interval and meet the modification conditions, and the tracking crosses one interval, the portion of the theoretical azimuth guidance angle of the antenna exceeding 270° will be reduced by 360°.

[0081] See Figure 5 Understood. This situation corresponds to the starting angle of the azimuth being ④, and the ending angle also being ④. That is, in the theoretical azimuth guidance angle of the antenna, the starting angle of the azimuth is between 270° and 360°, and the ending angle is also between 270° and 360°. In this case, the azimuth needs to be adjusted; that is, the portion of the azimuth exceeding 270° should be subtracted by 360°.

[0082] (ii) Cases spanning two intervals:

[0083] Specifically, for cases that cross two intervals and meet the modification conditions, the theoretical azimuth guidance angle of the antenna will be adjusted accordingly, including:

[0084] 2a) For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the third interval and the ending angle is in the fourth interval, subtract 360° from the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180°.

[0085] See Figure 5 Understood. This situation corresponds to the antenna rotating clockwise, with the starting angle of the azimuth at ③ and the ending angle at ④. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 180°.

[0086] 2b) For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval and the ending angle is in the third interval, subtract 360° from the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180°.

[0087] See Figure 5 Understood. This situation corresponds to the antenna rotating counterclockwise, with the starting angle of the azimuth at ④ and the ending angle at ③. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 180°.

[0088] 2c) For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° is reduced by 360°.

[0089] See Figure 5 Understood. This situation corresponds to the antenna rotating clockwise, with the starting angle of the azimuth angle at ④ and the ending angle at ①. In this case, the azimuth angle needs to be adjusted by subtracting 360° from the portion of the azimuth angle exceeding 90°.

[0090] 2d) For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° is reduced by 360°.

[0091] See Figure 5 Understood. This situation corresponds to the antenna rotating counterclockwise, with the starting angle of the azimuth at ① and the ending angle at ④. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 90°.

[0092] (III) Cases involving crossing three intervals:

[0093] Specifically, for cases that meet the modification conditions and span three intervals, the corresponding theoretical azimuth guidance angle of the antenna will be adjusted, including:

[0094] 3a) For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the second interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° is reduced by 360°.

[0095] See Figure 5Understood. This situation corresponds to the antenna rotating clockwise, with the starting angle of the azimuth at ② and the ending angle at ④. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 90°.

[0096] 3b) For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° is reduced by 360°.

[0097] See Figure 5 Understood. This situation corresponds to the antenna rotating counterclockwise, with the starting angle of the azimuth at ④ and the ending angle at ②. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 90°.

[0098] 3c) In cases where the antenna rotates clockwise, the starting angle of the theoretical azimuth guidance angle is in the third interval and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle exceeding 180° is reduced by 360°.

[0099] See Figure 5 Understood. This situation corresponds to the antenna rotating clockwise, with the starting angle of the azimuth angle at ③ and the ending angle at ①. In this case, the azimuth angle needs to be adjusted, that is, the portion of the azimuth angle exceeding 180° is subtracted by 360°.

[0100] 3d) For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the third interval, subtract 360° from the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180°.

[0101] See Figure 5 Understood. This situation corresponds to the antenna rotating counterclockwise, with the starting angle of the azimuth at ① and the ending angle at ③. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 180°.

[0102] 3e) For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, subtract 360° from the portion of the theoretical azimuth guidance angle of the antenna that exceeds 270°.

[0103] See Figure 5Understood. This situation corresponds to the antenna rotating clockwise, with the starting angle of the azimuth at ④ and the ending angle at ②. In this case, the azimuth needs to be adjusted by subtracting 360° from the portion of the azimuth exceeding 270°.

[0104] 3f) For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the second interval, and the ending angle is in the fourth interval, subtract 360° from the portion of the theoretical azimuth guidance angle of the antenna that exceeds 270°.

[0105] See Figure 5 Understood. This situation corresponds to the antenna rotating counterclockwise, with the starting angle of the azimuth angle at ② and the ending angle at ④. In this case, the azimuth angle needs to be adjusted, specifically by subtracting 360° from the portion of the azimuth angle exceeding 270°.

[0106] It should be noted that although 3a), 3b), 3e), and 3f) all start and end at ② and ④, their overall rotation areas are different. The difference lies in whether the area they pass through is ① or ③. The orientation value of each track is used to determine whether it passes through area ① or ③. If it is in ①, it is handled as in 3a) and 3b); if it is in ③, it is handled as in 3e) and 3f).

[0107] After the above correction process, the theoretical azimuth guidance angles of some antennas that meet the modification conditions have been corrected. Therefore, the actual antenna guidance angles at each moment after the correction are completed still include a theoretical azimuth guidance angle and a theoretical elevation guidance angle.

[0108] Those skilled in the art will understand that by modifying the azimuth angle rotation range of the azimuth-elevation type mount antenna of the ground control station from 0 to 360° to ±270° with a zero-crossing switch, the actual effective rotation range of the antenna becomes 540°. Then, by correcting the calculated theoretical guidance angle of the antenna at each moment when the control station tracks and observes the LEO satellite using the guidance angle correction method for ground station antenna non-reversal tracking of LEO satellites proposed in this invention, the guidance antenna can maintain continuous observation of the satellite during each orbit observation time when the satellite passes over the ground. This can minimize the occurrence of forced interruption of information transmission due to signal loss.

[0109] S4, Generate an antenna guidance file according to a preset format based on the actual antenna guidance angle at each moment;

[0110] The preset format can be set as needed, for example, it can be YYYY / MM / DD hh / mm / ss AZ EL. Here, YYYY / MM / DD represents year / month / day, hh / mm / ss represents hour / minute / second, AZ is the azimuth angle, and EL is the elevation angle.

[0111] S5, by loading the antenna guidance file, the modified telemetry and control station antenna is driven to rotate according to the actual antenna guidance angle in the antenna guidance file, so as to continuously track and observe the LEO satellite when the satellite passes over.

[0112] In this step, the antenna guidance file can be automatically loaded and driven by the ACU (Adaptive Control Unit) so that the modified telemetry and control station antenna rotates according to the actual antenna guidance angle at each moment in the antenna guidance file.

[0113] It is understandable that the ACU drives the antenna guidance file to rotate the antenna according to the actual guidance angle in the antenna guidance file in an orbit tracking manner, and begins uninterrupted tracking and observation of the LEO satellite when the satellite passes overhead. Specifically, the orbit tracking working principle is that the antenna control unit calculates the azimuth and elevation angles pointing at the satellite based on the satellite orbit data sent by the host computer, and drives the antenna to point at the target, completing the position closed loop of azimuth and elevation angles.

[0114] Those skilled in the art will understand that when the azimuth angle rotation range of a traditional ground-based telemetry and control station's azimuth-elevation mount antenna is 0–360°, there is a transition in the azimuth guidance angle of the ground antenna when a LEO satellite passes overhead, rotating clockwise from 360° to 0° or counterclockwise from 0° to 360°. When this occurs, due to the mechanical limitations of the azimuth-elevation mount antenna, the antenna must rotate 360° in both cases to continue observation. During satellite tracking by the ground-based telemetry and control station, this antenna rotation will cause telemetry signal loss, forcing an interruption of information transmission and thus reducing the effective observation time of the ground-based telemetry and control station when the satellite passes overhead.

[0115] The proposed method for non-reversal antenna tracking of LEO satellites by ground stations enables uninterrupted tracking of LEO satellites by ground control stations during their transit. This completely solves the problem of forced interruption of uplink and downlink information transmission between ground control stations and satellites caused by the reversal of azimuth-elevation mount antennas. This allows ground control station antennas to continuously complete uplink and downlink information transmission between the satellite and ground control station during LEO satellite transits, increasing the effective observation time of the satellite by ground control stations. This makes the tracking, control, and management of the LEO satellite constellation more flexible and controllable, and has significant practical engineering value.

[0116] It should be noted that, in the description of this invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0117] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0118] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for antenna-free tracking of LEO satellites observed from an earth station, characterized in that, include: The azimuth angle rotation range of the ground telemetry and control station's azimuth-elevation type mount antenna was modified from 0 to 360° to ±270° with a zero-crossing switch, resulting in the modified telemetry and control station antenna. Based on the position information of the modified telemetry and control station antenna and the satellite's orbit, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated. The theoretical antenna guidance angle at any moment includes the theoretical antenna azimuth guidance angle and the theoretical antenna elevation guidance angle. The original antenna azimuth angle rotation range is divided into 4 intervals. Based on the different situations of the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the modified telemetry and control station antenna when the satellite passes over, the theoretical azimuth guidance angle of the antenna that meets the modification conditions is corrected, so as to obtain the actual guidance angle of the antenna at each moment. The actual antenna guidance angle at each moment is used to generate an antenna guidance file according to a preset format; By loading the antenna guidance file, the modified telemetry and control station antenna is driven to rotate according to the actual antenna guidance angle in the antenna guidance file, thereby enabling uninterrupted tracking and observation of LEO satellites when they pass overhead.

2. The method according to claim 1, characterized in that, The azimuth angle rotation range of the ground control station's azimuth-elevation mount antenna was modified from 0–360° to ±270° with a zero-crossing switch, resulting in the modified control station antenna, which includes: By installing a preset azimuth limiting device on the azimuth-elevation type mount antenna of the ground control station, the azimuth angle rotation range of the azimuth-elevation type mount antenna of the ground control station is modified from 0 to 360° to ±270° with a zero-crossing switch, thus obtaining the modified control station antenna; wherein, the preset azimuth limiting device includes a stop block installed on the azimuth column of the azimuth-elevation type mount antenna of the ground control station, and a micro switch installed on the azimuth turntable.

3. The method according to claim 1, characterized in that, Based on the position information of the modified tracking and control station antenna and the satellite's orbit, the theoretical antenna guidance angle at each moment when the tracking and control station tracks and observes the LEO satellite is calculated, including: Using the two orbital elements of the LEO satellite and the station coordinates of the modified telemetry and control station antenna, the theoretical antenna guidance angle at each moment when the telemetry and control station tracks and observes the LEO satellite is calculated according to the azimuth angle and elevation angle algorithm.

4. The method according to claim 1, characterized in that, The original antenna azimuth angle rotation range is divided into 4 equal intervals, including: Divide the 360° azimuth rotation range into four equal sections along the clockwise direction: the first section, the second section, the third section, and the fourth section.

5. The method according to claim 4, characterized in that, The process involves correcting the theoretical azimuth guidance angles of the modified telemetry and control station antennas based on the different ranges of the starting and ending angles during satellite transit, for those meeting the modification conditions. This includes: Based on the range of the starting and ending angles of the theoretical azimuth guidance angle of the modified telemetry and control station antenna during satellite transit, the theoretical azimuth guidance angle of the antenna is adjusted accordingly for cases that meet the modification conditions, such as crossing one interval, crossing two intervals, and crossing three intervals.

6. The method according to claim 5, characterized in that, For cases that cross a certain interval and meet the modification conditions, the corresponding theoretical azimuth guidance angle of the antenna should be adjusted, including: For cases where the starting angle and ending angle of the tracking in the theoretical azimuth guidance angle of the antenna are both in the fourth interval and meet the modification conditions, and the tracking crosses one interval, the portion of the theoretical azimuth guidance angle of the antenna exceeding 270° will be reduced by 360°.

7. The method according to claim 5, characterized in that, For cases that cross two intervals and meet the modification conditions, the corresponding theoretical azimuth guidance angle of the antenna should be adjusted, including: For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the third interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°. For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the third interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°. For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°. For cases that meet the modification conditions and span two intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°.

8. The method according to claim 5, characterized in that, For cases that meet the modification conditions and span three intervals, the corresponding theoretical azimuth guidance angle of the antenna will be adjusted, including: For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the second interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°. For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 90° will be reduced by 360°. For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the third interval, and the ending angle is in the first interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°. For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the first interval, and the ending angle is in the third interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 180° will be reduced by 360°. For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is clockwise, the starting angle of the theoretical azimuth guidance angle of the antenna is in the fourth interval, and the ending angle is in the second interval, the portion of the theoretical azimuth guidance angle of the antenna that exceeds 270° will be reduced by 360°. For cases that meet the modification conditions and span three intervals, where the antenna rotation direction is counterclockwise, the starting angle of the theoretical azimuth guidance angle is in the second interval, and the ending angle is in the fourth interval, the portion of the theoretical azimuth guidance angle exceeding 270° will be reduced by 360°.

9. The method according to claim 1, characterized in that, By loading the antenna guidance file, the modified telemetry and control station antenna is driven to rotate according to the actual antenna guidance angle in the antenna guidance file, including: The antenna guidance file is automatically loaded and driven by the ACU so that the modified telemetry and control station antenna rotates according to the actual antenna guidance angle at each moment in the antenna guidance file.

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