A servo tracking system for an airborne mobile antenna

Abstract

This invention provides a servo tracking system for an airborne on-the-move satellite communication antenna, which solves the problem of poor tracking performance of on-the-move antennas in airborne satellite communication. The system includes a servo tracking module connected to an RF module and a signal transmission module. The servo tracking module has a servo controller and a GPS / BeiDou positioning unit, as well as an attitude sensor and a stepper motor. The stepper motor is connected to the RF module via a transmission mechanism. This invention offers advantages such as good antenna tracking performance and structural stability.

Description

Technical Field

[0001] This utility model belongs to the field of servo tracking technology, specifically relating to a servo tracking system for an airborne mobile antenna. Background Technology

[0002] In the field of satellite mobile communication, my country has long relied on foreign satellite communication systems, such as the European Satellite System, Inmarsat, and Globalstar, which are extremely costly and lack security and controllability. "Tiantong-1" is my country's first satellite mobile communication system. The "Tiantong-1" 01 satellite was successfully launched on August 6, 2016, ushering in a new era for my country with its own independent satellite mobile communication system. This system has SMS, voice, and data communication functions, with a maximum data transmission rate of 384kbps, suitable for use on vehicle-mounted, ship-mounted, and airborne platforms for long-distance, wide-area, and roaming applications. Mobile satellite communication antenna technology and products are mainly used for real-time communication on moving vehicles and ships. The core technology is to ensure that the satellite antenna always points to the selected communication satellite even under changes in the vehicle's attitude and heading. For civilian vehicle- and ship-mounted mobile satellite communication antennas, there are relatively mature products both domestically and internationally, widely used in mobile satellite television, mobile voice and data communication, and mobile internet. However, mobile satellite communication antenna products for airborne satellite communication are still a gap in the domestic market.

[0003] To address the shortcomings of existing technologies, people have conducted long-term explorations and proposed various solutions. For example, Chinese patent literature discloses a method and device for satellite mobile terminal antenna loss identification [202211548033.0], which includes finding the origin positions of the polarization motor, pitch motor, roll motor, and azimuth motor to obtain the actual angle of the antenna; obtaining the latitude and longitude coordinates of the carrier and calculating the theoretical angle of the antenna based on the latitude and longitude coordinates; controlling the rotation of the polarization motor, pitch motor, roll motor, and azimuth motor based on the actual angle of the antenna to make the error between the actual angle and the theoretical angle of the antenna zero; the azimuth motor starts rotating from the initial angle, while the pitch motor controls the antenna surface to maintain a preset pitch angle to obtain the satellite signal; and the antenna is blocked based on the satellite signal to obtain a radar chart analysis graph.

[0004] The above solution has solved the antenna maintenance problem to some extent, but it still has many shortcomings, such as poor tracking performance of airborne satellite communication antennas on the move. Utility Model Content

[0005] The purpose of this invention is to address the above-mentioned problems by providing a reasonably designed servo tracking system for an airborne mobile antenna with good servo tracking performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a servo tracking system for an airborne mobile antenna, comprising a servo tracking module, the servo tracking module being connected to an RF module and a signal transmission module, the servo tracking module having a servo controller and a GPS / BeiDou positioning unit, the servo tracking module having an attitude sensor and a stepper motor, the stepper motor being connected to the RF module through a transmission mechanism.

[0007] In the aforementioned servo tracking system for an airborne mobile antenna, the servo controller includes a processing unit connected to a GPS / BeiDou positioning unit and an attitude sensor. The processing unit is connected to a stepper motor via a digital-to-analog converter and a servo filter amplification unit. The transmission mechanism is connected to the processing unit via an analog-to-digital converter. The processing unit is connected to the radio frequency module via a beam control unit. The stepper motor includes an azimuth motor and a pitch motor.

[0008] The servo filter amplifier unit has an RMS power detector U9, which is connected to an RF coupler N8. The RF coupler N8 is connected to an RF coaxial connector and an attenuator U10. The attenuator U10 is connected to a broadband amplifier N9, an attenuator U11, an RF amplifier N10, a function signal generator V5, a function signal generator V11, a function signal generator V10, and an RF coaxial connector.

[0009] The servo filter amplifier unit has an amplifier U12 and the amplifier U12 is connected to a field-effect transistor U13. The servo filter amplifier unit has a driver ICU14.

[0010] In the aforementioned servo tracking system for an airborne mobile antenna, the radio frequency module includes an antenna array, which is connected to a beam control unit and a stepper motor. The antenna array is connected to a LAN unit and a PA unit via a duplexer, and the LAN unit and PA unit are connected to a signal transmission module.

[0011] The duplexer has a filter U8 connected to an RF coaxial connector, and the filter U8 is connected in sequence to an RF low noise amplifier U5, a filter U1, an RF low noise amplifier U3, a filter U6, a broadband amplifier N3, an attenuator U10, and a filter U12.

[0012] The duplexer has a filter U2 connected to an RF coaxial connector. The filter U2 is connected to an attenuator U4, a broadband amplifier N2, a filter U13, and a combiner N4 in turn. The duplexer is connected to an SAW filter U14 connected to the RF coaxial connector. The SAW filter U14 is connected to a broadband amplifier N6, an attenuator U15, an SAW filter U16, and a combiner N5 in turn. The combiner N4 is connected to the combiner N5 and is connected to three RF coaxial connectors.

[0013] The duplexer has an operational amplifier N7 and a buck converter N1. The duplexer has a field-effect transistor U7 connected to a field-effect transistor U9 and a field-effect transistor U11.

[0014] In the aforementioned servo tracking system for an airborne mobile antenna, the signal transmission module includes a one-line communication unit, which is connected to a LAN unit, a PA unit, and a GPS / BeiDou positioning unit. The one-line communication unit is also connected to a terminal user equipped with a power supply.

[0015] The one-line communication unit has an RF low-noise amplifier U15, which is connected to three RF coaxial connectors. The one-line communication unit has two sets of RF coaxial connectors that are connected in pairs.

[0016] In the aforementioned servo tracking system for an airborne mobile communication antenna, the transmission mechanism includes an antenna base, a rotating seat body rotatably connected to the antenna base via a rotary joint, and an antenna bracket rotatably connected to the rotating seat body. A fixed gear with its central axis coinciding with the central axis of the rotary joint is mounted on the antenna base. An azimuth motor is mounted on the rotating seat body, and its output end meshes with the fixed gear for transmission. A transmission pulley is mounted on the antenna bracket, and an elevation motor is mounted on the rotating seat body, with its output end meshing with the transmission pulley via a transmission belt. An antenna array is mounted on the antenna bracket.

[0017] In the aforementioned servo tracking system for an airborne mobile antenna, a rotating bearing and a vibration damping pad are installed between the antenna base and the rotating body; an electric heating unit is installed between the rotating body and the antenna base and / or the antenna support.

[0018] A servo tracking method for an airborne mobile antenna, employing the aforementioned servo tracking system for the airborne mobile antenna, includes the following steps:

[0019] S1: Initial star alignment;

[0020] S11: System startup;

[0021] S12: Obtain satellite parameters;

[0022] S13: Obtain the carrier status;

[0023] S14: Calculate the theoretical pointing angle;

[0024] S15: Coordinate system transformation;

[0025] S16: Calculate the driving angle in the vehicle coordinate system;

[0026] S17: Drive motor positioning;

[0027] S18: Signal detection and locking;

[0028] S2: Inertial tracking.

[0029] In the above-described servo tracking method for an airborne mobile antenna, step S2 includes the following steps:

[0030] S21: Pitch axis inertial tracking;

[0031] S22: Azimuth axis inertial tracking.

[0032] In the above-described servo tracking method for an airborne mobile antenna, step S21 includes the following steps:

[0033] S211: Disturbance sensing;

[0034] S212: Compensation calculation;

[0035] S213: Drive compensation;

[0036] S214: Loop.

[0037] In the above-described servo tracking method for an airborne mobile antenna, step S22 includes the following steps:

[0038] S221: Disturbance sensing and state feedback;

[0039] S222: Deviation calculation;

[0040] S223: Control calculation;

[0041] S224: Drive compensation;

[0042] S225: Closed-loop feedback;

[0043] S226: Loop.

[0044] Compared with existing technologies, the advantages of this utility model are as follows: the servo tracking system performs multi-sensor fusion, and ensures high-precision pointing and tracking of the airborne mobile satellite antenna through real-time calculation and dual-axis independent control; it performs disturbance perception and real-time compensation to achieve closed-loop control, and has good anti-interference and dynamic compensation capabilities; the system can achieve automatic initial satellite alignment and fully automatic tracking, and has a high level of intelligence and automation. Attached Figure Description

[0045] Figure 1 This is a system schematic diagram of this utility model;

[0046] Figure 2 This is another system schematic diagram of this utility model;

[0047] Figure 3 This is a schematic diagram of the radio frequency module of this utility model;

[0048] Figure 4This is another structural schematic diagram of the radio frequency module of this utility model;

[0049] Figure 5 This is another structural schematic diagram of the radio frequency module of this utility model;

[0050] Figure 6 This is another structural schematic diagram of the radio frequency module of this utility model;

[0051] Figure 7 This is the circuit diagram of the duplexer of this utility model;

[0052] Figure 8 This is the circuit schematic diagram of the servo filter amplifier unit of this utility model;

[0053] Figure 9 This is the circuit schematic diagram of the one-wire communication unit of this utility model;

[0054] In the diagram, the components are: servo tracking module 1, servo controller 11, GPS / BeiDou positioning unit 12, attitude sensor 13, stepper motor 14, azimuth motor 141, pitch motor 142, processing unit 15, digital-to-analog converter 16, servo filter and amplifier unit 17, analog-to-digital converter 18, beam control unit 19, RF module 2, antenna array 21, duplexer 22, LAN unit 23, PA unit 24, signal transmission module 3, one-line communication unit 31, end user 32, power supply 33, transmission mechanism 4, antenna base 41, rotary joint 42, rotary seat 43, fixed gear 44, antenna bracket 45, transmission pulley 46, transmission belt 47, rotating bearing 48, and vibration damping pad 49. Detailed Implementation

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0056] like Figure 1-9As shown, a servo tracking system for an airborne mobile communication antenna includes a servo tracking module 1, which is connected to an RF module 2 and a signal transmission module 3. The servo tracking module 1 has a servo controller 11 and a GPS / BeiDou positioning unit 12, an attitude sensor 13, and a stepper motor 14. The stepper motor 14 is connected to the RF module 2 via a transmission mechanism 4. The RF module 2 mainly performs the functions of receiving and transmitting satellite signals: after the antenna array 21 of the RF module 2 receives the corresponding satellite downlink signal, it is pre-processed by pre-amplification and filtering and then sent to the signal transmission module 3. It is then sent to the host to complete down-conversion, demodulation, and decoding, and finally generates complete satellite communication information, which is sent to the terminal user 32 to complete the satellite communication reception function. Correspondingly, the information sent by the terminal user 32 is encoded and modulated by the host and then up-converted to the satellite uplink frequency band and sent to the signal transmission module 3. After being amplified by the power amplifier inside the RF module 2, it is sent to the antenna array 21 to complete the satellite communication transmission function.

[0057] Specifically, the servo controller 11 includes a processing unit 15, which is connected to the GPS / BeiDou positioning unit 12 and the attitude sensor 13. The processing unit 15 is connected to the stepper motor 14 through the digital-to-analog converter 16 and the servo filter amplification unit 17. The transmission mechanism 4 is connected to the processing unit 15 through the analog-to-digital converter 18. The processing unit 15 is connected to the RF module 2 through the beam control unit 19. The stepper motor 14 includes an azimuth motor 141 and a pitch motor 142. The servo tracking module 1 enables the RF module 2 to automatically align with the satellite and ultimately achieve communication while on the move. Relying on the position sensor, heading sensor, and attitude sensor inside the servo tracking module 1, the current status information of the device is obtained. At the same time, the pitch and azimuth motion angles required for tracking are uniformly calculated according to the preset target position, completing the satellite acquisition process of the entire device. It is worth mentioning that, in order to meet airborne requirements, the entire servo tracking module 1 adopts a two-dimensional scanning method. For overhead tracking, the device applies the phase scanning function of the antenna to overhead tracking, realizing the full-angle tracking capability of the two-dimensional turntable.

[0058] After receiving navigation signals within the field of view, the GPS / BeiDou positioning unit 12 installed inside the servo tracking module 1 decodes them using a dedicated chip to generate navigation information. The processing unit 15 installed inside the servo tracking module 1 extracts the host's requirement information and, according to certain rules, fits it with the device's status information before sending it to the signal transmission module 3.

[0059] The servo filter amplification unit 17 has an RMS power detector U9, which is connected to an RF coupler N8. The RF coupler N8 is connected to an RF coaxial connector and an attenuator U10. The attenuator U10 is connected one by one to a broadband amplifier N9, an attenuator U11, an RF amplifier N10, a function signal generator V5, a function signal generator V11, a function signal generator V10, and an RF coaxial connector.

[0060] The servo filter amplifier unit 17 has an amplifier U12 and the amplifier U12 is connected to a field-effect transistor U13. The servo filter amplifier unit 17 has a driver ICU14.

[0061] Specifically, the radio frequency module 2 includes an antenna array 21, which is connected to the beam control unit 19 and the stepper motor 14. The antenna array 21 is connected to a LAN unit 23 and a PA unit 24 via a duplexer 22. The LAN unit 23 and the PA unit 24 are connected to the signal transmission module 3.

[0062] The duplexer 22 has a filter U8 connected to the RF coaxial connector, and the filter U8 is connected one by one to the RF low noise amplifier U5, filter U1, RF low noise amplifier U3, filter U6, broadband amplifier N3, attenuator U10 and filter U12.

[0063] The duplexer 22 has a filter U2 connected to an RF coaxial connector. The filter U2 is connected to an attenuator U4, a broadband amplifier N2, a filter U13, and a combiner N4 in turn. The duplexer 22 is connected to an SAW filter U14 connected to the RF coaxial connector. The SAW filter U14 is connected to a broadband amplifier N6, an attenuator U15, an SAW filter U16, and a combiner N5 in turn. The combiner N4 is connected to the combiner N5 and is connected to three RF coaxial connectors.

[0064] The duplexer 22 has an operational amplifier N7 and a buck converter N1. The duplexer 22 has a field-effect transistor U7 connected to a field-effect transistor U9 and a field-effect transistor U11.

[0065] Furthermore, the signal transmission module 3 includes a one-line communication unit 31, which is connected to the LAN unit 23, the PA unit 24 and the GPS / BeiDou positioning unit 12. The one-line communication unit 31 is connected to a terminal user 32 equipped with a power supply 33.

[0066] The one-line communication unit 31 has an RF low-noise amplifier U15, which is connected to three RF coaxial connectors. The one-line communication unit 31 also has two sets of RF coaxial connectors connected in pairs. The signal transmission module 3 integrates the modulated data information, RF signal, and power supply functions to generate a single transmission signal, which is then sent to the processing unit 15. The host computer is equipped with a similar signal transmission module 3, which decomposes the power supply, control, status, and communication information according to a preset process and connects them to different processing units of the host computer to complete the entire process, thereby realizing complete satellite communication functionality.

[0067] Furthermore, the transmission mechanism 4 includes an antenna base 41, which is rotatably connected to a rotating seat 43 via a rotating joint 42. The rotating seat 43 is rotatably connected to an antenna bracket 45. A fixed gear 44, whose central axis coincides with the central axis of the rotating joint 42, is mounted on the antenna base 41. An azimuth motor 141 is mounted on the rotating seat 43, and its output end meshes with the fixed gear 44 for transmission. A transmission pulley 46 is mounted on the antenna bracket 45, and an elevation motor 142 is mounted on the rotating seat 43, with its output end meshing with the transmission pulley 46 via a transmission belt 47 for transmission. The antenna array 21 is mounted on the antenna bracket 45. The antenna bracket 45 is made of high-strength aviation aluminum profile with a hollowed-out back, which increases the surface flatness of the antenna array 21 while ensuring strength, further stabilizing the impedance and radiation characteristics of the printed circuit board antenna surface.

[0068] The radio frequency module 2 is directly mounted on the antenna array 21 on the rotating base 43. As the servo tracking module 1 rotates in the azimuth plane, this design increases cable loss slightly, but the load on its pitch motor 142 can be greatly reduced. On the one hand, it reduces the power consumption of the servo tracking module 1, and on the other hand, it improves the overall reliability of the equipment.

[0069] Servo tracking module 1 is equipped with differential GPS / BeiDou for heading measurement and position determination. It can provide current position data and corresponding radio frequency information to signal transmission module 3, which is transmitted through the transmission subsystem.

[0070] The GPS / BeiDou positioning unit 12 employs a high-precision differential positioning module, capable of transmitting the device's position and heading information in real time. The attitude sensor 13 is a sensitive measurement device for the antenna's attitude angle, providing real-time attitude parameters such as azimuth, pitch, and roll for the entire device. Among these parameters, the response speed and accuracy of the attitude sensor 13 significantly impact the pointing accuracy of the entire servo system. The electrical signals generated by attitude changes are converted from digital to analog, filtered, and amplified by the servo motor before being sent to the stepper motor 14. This motor then drives the antenna support 45 of the antenna array 21 to rotate in two dimensions via transmission gears. Mechanically, a limit switch for the antenna support 45's rotation in the pitch direction is also designed to ensure safe operation of the system in the pitch direction.

[0071] In addition, to further improve environmental adaptability and reduce the impact of vibration on the entire servo device, a rotating bearing 48 and a vibration damping pad 49 are installed between the antenna base 41 and the rotating seat 43. The vibration damping pad 49 filters high-frequency vibrations from the outside, and the meshing gear adopts an elastic tracking structure to avoid damage to the transmission mechanism 4 caused by large impacts.

[0072] A heating element is installed between the rotating base 43 and the antenna base 41 and / or the antenna bracket 45. To ensure normal startup at low temperatures, the machine needs to be preheated before use. The preheating of the servo tracking system adopts a combination of overall preheating and preheating of key locations. Heating elements are arranged around the servo tracking system to increase the overall heating capacity of the servo tracking system. At the same time, heating measures are added to key components, sensors, and controller components to ensure the ability of key components to work in extremely low temperature environments.

[0073] A servo tracking method for an airborne mobile antenna, employing the aforementioned servo tracking system for the airborne mobile antenna, includes the following steps:

[0074] S1: Initial satellite alignment. The mobile antenna is mounted on the carrier and moves within a relative space and coordinate system. The main task of initial satellite alignment is to calculate the corresponding rotation angles of the drive elevation and azimuth servo motors through relative coordinate calculations. Ultimately, this physically aligns the antenna's radiating surface normal to the target satellite. To better understand and calculate this, several reference frames need to be introduced:

[0075] 1. Earth coordinate system: Assume the Earth's center is the origin, the direction from the Earth's center to the North Pole is the Z-axis, the X-axis and Y-axis are at an angle of 90° and point from the Earth's center to the equator.

[0076] 2. Ground coordinate system: A three-dimensional rectangular coordinate system with a point on the Earth's surface as the origin, the Z-axis perpendicular to the tangent plane of that point with upwards as positive, the positive X-axis pointing due east of that point, and the positive Y-axis pointing due north of that point.

[0077] 3. Carrier Coordinate System: Since the mobile antenna is mounted on the carrier, its pointing direction will inevitably change with the movement of the carrier. Considering that the mobile antenna is fixed relative to the carrier, a carrier coordinate system needs to be established. The position where the antenna is mounted on the carrier is taken as the origin, the direction of movement is taken as the Y-axis, and the Z-axis is perpendicular to the carrier plane and its positive direction is defined upward. The X-axis is perpendicular to the Y-axis and Z-axis and points to the right as positive.

[0078] By changing the azimuth and elevation angles of the array antenna radiating surface in the mobile satellite communication antenna, it is theoretically possible to point at and track a target satellite from any location on Earth covered by the satellite beam.

[0079] Simultaneously, the longitude of the target satellite is determined based on the satellite calendar, and the elevation and azimuth angles of the antenna array corresponding to the carrier are calculated by combining the latitude and longitude of the equipment's geographical location. The azimuth angle, denoted by A0, is defined as the angle between the projection of the line connecting the on-the-ground antenna and the target satellite onto the ground and the due south direction. The elevation angle, denoted by E0, is defined as the angle between the line connecting the on-the-ground antenna and the target satellite and the ground plane. The elevation angle ranges from 0 to 90°. The formulas for calculating A0 and E0 are:

[0080]

[0081]

[0082] In the formula: λ s Let λ be the longitude of the target satellite. r φ r These are the latitude and longitude of the ground location of the mobile antenna equipment.

[0083] A0 uses the positive Y-axis of the ground coordinate system as the zero-degree reference for the azimuth angle. For an airborne, mobile satellite communication antenna, when the antenna begins the initial satellite alignment process, the azimuth angle of the array antenna can rotate freely within a 360° range. To precisely control the array antenna's direction, the angle between the array antenna's direction and the positive Y-axis of the ground coordinate system must be considered. Therefore, the precise azimuth angle for a mobile satellite communication antenna to align with the satellite is...

[0084]

[0085] Where Hx is the angle between the positive Y-axis of the ground coordinate system and the direction pointed to by the array antenna. Assume the difference between the longitude of the ground location of the on-the-fly antenna and the longitude of the target satellite's location is λ, i.e., λ = λ s -λ r Therefore, the calculation of the aforementioned azimuth and elevation angles can be written as:

[0086]

[0087]

[0088] There is a certain relationship between the ground coordinate system and the vehicle coordinate system; their transformation relationship can be obtained through a set of matrices and rotation transformations. The formula is as follows:

[0089]

[0090] Where Y is the angle between the Y-axis of the carrier and the positive Y-axis of the ground coordinate system, R is the angle between the horizontal plane and the transverse axis of the carrier, and P is the angle between the horizontal plane and the longitudinal axis of the carrier.

[0091] The required pointing angle of the array antenna in the carrier coordinate system can be calculated using the rotation matrix.

[0092] Let r be defined as the distance between the target satellite and the origin of the ground coordinate system. The transformation relationship between the target satellite's coordinates and A0 and E0 can be expressed by the following formula.

[0093]

[0094] The rectangular coordinates of the satellite in the carrier coordinate system can be obtained by the following formula:

[0095]

[0096] The azimuth angle A and elevation angle E of the target satellite in the carrier coordinate system can be calculated using the following formulas:

[0097]

[0098] E = ArcSin(Z2);

[0099] Because the actual calculated elevation angle and the range of the ArcTan function [-90°, 90°] are consistent, the calculated result E is the actual elevation angle. However, the actual azimuth angle is inconsistent with the range of the ArcSin function, so the final actual azimuth angle must be determined by looking up a table. The actual azimuth angle value can be found in the table below.

[0100] + + A+180° - + A-180° - - A + - A

[0101] Based on the above calculation relationship, the differential positioning module and attitude sensor provide the antenna's own geographical location information, heading information, attitude information, etc., as well as the satellite orbit information stored in the processing unit. This allows for the accurate calculation of the angles that the pitch and azimuth motors need to rotate, thereby driving the motors to move within the predetermined range and completing the initial satellite alignment.

[0102] Specifically, step S1 includes the following steps:

[0103] S11: System startup. After the system is powered on, the servo tracking system receives control commands. The data includes the satellite's orbital parameters S1. If not sent, the parameters used last time will be used.

[0104] S12: Obtain satellite parameters. The GPS / BeiDou positioning module 12 outputs the geographical location information of the terminal to the processing unit 15.

[0105] S13: Obtain the carrier status;

[0106] S14: Calculate the theoretical pointing angle;

[0107] S15: Coordinate system transformation;

[0108] S16: Calculate the driving angle in the carrier coordinate system. The processing unit 15 calculates the antenna elevation angle at the location of the terminal antenna using the values ​​of S1 and S2.

[0109] S17: Drive the motor to position, control the pitch motor 142 to adjust to the corresponding angle, and complete the initial star alignment;

[0110] S18: Signal detection and locking. Detects downlink signals from the satellite and initiates inertial tracking after detecting and locking onto the received signal.

[0111] S2: Inertial tracking. The system first detects the current attitude of the on-the-move antenna using attitude sensor 13 to determine whether the antenna array 21 is accurately aligned with the target satellite. If the antenna array 21 is aligned with the target satellite, it maintains its current operating attitude while continuously and cyclically checking its pointing direction. If it is determined that the antenna array is not aligned with the satellite and there is an error in azimuth or elevation, the system performs detailed calculations on the attitude information of the antenna array 21. Using the inertial tracking control algorithm, it calculates the required steering compensation in both elevation and azimuth dimensions and drives the stepper motor 14 to perform reverse attitude compensation for the errors in both dimensions. After compensation, the system checks the current antenna position again. If it still cannot accurately align with the target satellite, the above inertial tracking steps are repeated until the antenna array 21 accurately points to the target satellite.

[0112] In detail, in step S2, processing unit 15 controls two motors to perform a conical scanning motion, ensuring the carrier-to-noise ratio of the satellite signal is always at its maximum. It also uses attitude sensor 13 to determine the displacement and direction of the carrier in real time. When the carrier moves or changes direction, processing unit 11 controls stepper motor 14 to reverse the motion, ensuring the antenna radiation direction is always aligned with the satellite. Ultimately, this achieves high-precision tracking of the carrier during high-speed movement and obtains the maximum value of the target signal, thus realizing the on-the-move communication function. Specifically, this includes the following steps:

[0113] S21: Pitch axis inertial tracking. The purpose of pitch inertial tracking is to keep the pitch angle of antenna array 21 constant relative to the target satellite. The pitch angle sensing signal is output by a three-axis gyroscope mounted on the crossbeam of the moving mid-band antenna. The rotation axis of the pitch motor 142, which controls the pitch angle, is the same as the compensation pitch axis.

[0114] The three-axis gyroscope detects that the pitch axis is coaxial with the pitch rotation axis. Therefore, the difference in pitch system angular velocity compensation, when translated to the pitch system rotation axis, is the pitch angular velocity detected by the gyroscope. The system's structural design ensures that the gyroscope's pitch output is unaffected by the pitch motor 142; therefore, feedforward compensation control is used to achieve pitch attitude stability. Specifically, the control method is as follows: based on the pitch disturbance angular velocity measured by the gyroscope, the pitch angular position compensation is calculated, and the pitch motor 142 is driven to perform feedforward open-loop compensation.

[0115] S22: Azimuth axis inertial tracking. The purpose of azimuth-stabilized tracking is to ensure that the antenna's azimuth angle remains unchanged. The azimuth sensing signal is also output by a three-axis gyroscope. However, due to the installation position, the gyroscope detects both the azimuth disturbance angular velocity of the carrier and the rotational angular velocity of the device itself. Therefore, the aforementioned feedforward compensation method is not applicable to the azimuth-stabilized tracking system. Thus, azimuth-stabilized tracking adopts closed-loop control with the azimuth angular velocity output of the gyroscope as feedback.

[0116] The change in azimuth direction caused by the disturbance of the carrier and the rotation of its own azimuth motor 141 together form the azimuth angle deviation. The ultimate goal of azimuth control is to make the azimuth angle deviation zero.

[0117] In practical project implementation, the partitioned PID control algorithm, which is widely used and easy to implement in engineering applications, is adopted. The partitioned PID control algorithm divides the entire stable tracking dynamic process into several intervals based on the magnitude and trend of the tracking error, and selects appropriate PID parameters for each interval. Essentially, the partitioned PID control algorithm is a variable structure, variable parameter control method. It can adjust the parameters and structure of the control unit in real time according to the system's operating conditions, thereby obtaining satisfactory dynamic performance.

[0118] In addition, step S21 includes the following steps:

[0119] S211: Disturbance sensing;

[0120] S212: Compensation calculation;

[0121] S213: Drive compensation;

[0122] S214: Loop.

[0123] Meanwhile, step S22 includes the following steps:

[0124] S221: Disturbance sensing and state feedback;

[0125] S222: Deviation calculation;

[0126] S223: Control calculation;

[0127] S224: Drive compensation;

[0128] S225: Closed-loop feedback;

[0129] S226: Loop.

[0130] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

[0131] Although this document frequently uses terms such as servo tracking module 1, servo controller 11, GPS / BeiDou positioning unit 12, attitude sensor 13, stepper motor 14, azimuth motor 141, pitch motor 142, processing unit 15, digital-to-analog converter 16, servo filtering and amplification unit 17, analog-to-digital converter 18, beam control unit 19, RF module 2, antenna array 21, duplexer 22, LAN unit 23, PA unit 24, signal transmission module 3, one-line communication unit 31, end user 32, power supply 33, transmission mechanism 4, antenna base 41, rotary joint 42, rotary seat 43, fixed gear 44, antenna bracket 45, transmission pulley 46, transmission belt 47, rotating bearing 48, and vibration damping pad 49, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model.

Claims

1. A servo tracking system of airborne mobile satellite communication antenna, comprising a servo tracking module (1), the servo tracking module (1) is connected with a radio frequency module (2) and a signal transmission module (3), characterized in that, The servo tracking module (1) has a servo controller (11) and a GPS / BeiDou positioning unit (12). The servo tracking module (1) has an attitude sensor (13) and a stepper motor (14). The stepper motor (14) is connected to the radio frequency module (2) through a transmission mechanism (4).

2. A servo tracking system for an airborne mobile satellite antenna as claimed in claim 1, wherein, The servo controller (11) includes a processing unit (15), which is connected to a GPS / BeiDou positioning unit (12) and an attitude sensor (13). The processing unit (15) is connected to a stepper motor (14) through a digital-to-analog converter (16) and a servo filter amplification unit (17). The transmission mechanism (4) is connected to the processing unit (15) through an analog-to-digital converter (18). The processing unit (15) is connected to the radio frequency module (2) through a beam control unit (19). The stepper motor (14) includes an azimuth motor (141) and a pitch motor (142).

3. A servo tracking system for an airborne mobile satellite antenna as claimed in claim 2, wherein, The servo filter amplification unit (17) has an RMS power detector U9, which is connected to an RF coupler N8. The RF coupler N8 is connected to an RF coaxial connector and an attenuator U10. The attenuator U10 is connected to a broadband amplifier N9, an attenuator U11, an RF amplifier N10, a function signal generator V5, a function signal generator V11, a function signal generator V10, and an RF coaxial connector.

4. The servo tracking system of claim 2, wherein, The servo filter amplification unit (17) has an amplifier U12 and the amplifier U12 is connected to a field-effect transistor U13. The servo filter amplification unit (17) has a driver ICU14.

5. A servo tracking system for an airborne mobile satellite antenna as set forth in claim 2, wherein, The radio frequency module (2) includes an antenna array (21), which is connected to a beam control unit (19) and a stepper motor (14). The antenna array (21) is connected to a LAN unit (23) and a PA unit (24) via a duplexer (22). The LAN unit (23) and the PA unit (24) are connected to the signal transmission module (3).

6. A servo tracking system for an airborne mobile satellite antenna as claimed in claim 5, wherein, The duplexer (22) has a filter U8 connected to an RF coaxial connector, and the filter U8 is connected one by one to an RF low noise amplifier U5, a filter U1, a RF low noise amplifier U3, a filter U6, a broadband amplifier N3, an attenuator U10, and a filter U12.

7. A servo tracking system for an airborne mobile satellite antenna as claimed in claim 5, wherein, The duplexer (22) has a filter U2 connected to an RF coaxial connector. The filter U2 is connected to an attenuator U4, a broadband amplifier N2, a filter U13, and a combiner N4 one by one. The duplexer (22) is connected to a surface acoustic wave (SAW) filter U14 connected to an RF coaxial connector. The SAW filter U14 is connected to a broadband amplifier N6, an attenuator U15, an SAW filter U16, and a combiner N5 one by one. The combiner N4 is connected to the combiner N5 and is connected to three RF coaxial connectors.

8. A servo tracking system for an airborne mobile satellite antenna as set forth in claim 5, wherein, The duplexer (22) has an operational amplifier N7 and a buck converter N1. The duplexer (22) has a field-effect transistor U7 connected to a field-effect transistor U9 and a field-effect transistor U11.

9. The servo tracking system of claim 5, wherein, The signal transmission module (3) includes a one-line communication unit (31), which is connected to the LAN unit (23), the PA unit (24) and the GPS / BeiDou positioning unit (12). The one-line communication unit (31) is connected to a terminal user (32) equipped with a power supply (33). The one-line communication unit (31) has an RF low noise amplifier U15, which is connected to three RF coaxial connectors. The one-line communication unit (31) has two sets of RF coaxial connectors connected in pairs.

10. A servo tracking system for an airborne mobile satellite antenna as claimed in claim 9, wherein, The transmission mechanism (4) includes an antenna base (41), which is rotatably connected to a rotating seat (43) via a rotating joint (42). The rotating seat (43) is rotatably connected to an antenna bracket (45). A fixed gear (44) with its central axis aligned with the central axis of the rotating joint (42) is mounted on the antenna base (41). An azimuth motor (141) is mounted on the rotating seat (43) and its output end meshes with the fixed gear (44) for transmission. A transmission pulley (46) is mounted on the antenna bracket (45). A pitch motor (142) is mounted on the rotating seat (43) and its output end meshes with the transmission pulley (46) via a transmission belt (47). The antenna array (21) is mounted on the antenna bracket (45). A rotating bearing (48) and a vibration damping pad (49) are installed between the antenna base (41) and the rotating seat (43); an electric heating unit is installed between the rotating seat (43) and the antenna base (41) and / or the antenna bracket (45).

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