Implementation method for preventing mistaken tracking of adjacent geosynchronous orbit satellites for multi-beam antenna

Abstract

The invention provides an adjacent geosynchronous orbit satellite false-tracking prevention implementation method for a multi-beam antenna, aiming at the characteristic that a plurality of sets of independent feed source units in a bifocus multi-beam antenna are mounted on a feed source orbit through a movable pulley, a high-precision magnetic grid ruler is mounted along the feed source orbit, and a magnetic grid reading head is mounted on the feed source pulley; measuring the absolute position of the feed source pulley on the feed source track; according to the information of the to-be-tracked satellite, the theoretical position of the feed source unit corresponding to the to-be-tracked satellite on the feed source orbit is determined; according to the absolute position and the theoretical position, after the feed source unit is controlled to move to the theoretical position, the AGC level is used for finally determining the position of the feed source unit, and accurate tracking of the satellite to be tracked is achieved.

Description

Technical Field

[0001] This invention relates to the field of antenna control technology, specifically to a method for preventing mistracking of adjacent geosynchronous orbit satellites using a multi-beam antenna. Background Technology

[0002] A dual-focus multi-beam antenna is a novel antenna system characterized by wide-angle coverage, high gain, and multi-beam capability. The system consists of a main reflector and multiple independent feed elements arranged along a specific track arc. Each feed element includes a sub-reflector, feed source, frequency conversion and optical transmission equipment, etc. Figure 1 As shown, a certain type of dual-focus multi-beam antenna system has a main reflector size of 18 meters × 18 meters and eight independent feed elements. Each feed element is mounted on a movable trolley, enabling motorized adjustment in two directions—parallel and perpendicular to the geostationary orbit plane—on the orbital arc, thereby completing beam pointing switching and tracking of different geostationary satellites. This antenna is equivalent to eight 16-meter aperture antennas working together, capable of simultaneously receiving signals from up to eight geostationary satellites within a 21° field of view, with a minimum designed longitude interval of 2° between satellites.

[0003] During operation, the antenna employs a step-tracking method, achieving continuous tracking of satellite signals by precisely adjusting the spatial position of the feed. In the initial site setup phase, a total station is used to precisely calibrate the geometric relationships between the feed, sub-reflector, and primary reflector to ensure accurate beam positioning. However, due to the drift phenomenon of geostationary orbit satellites, coupled with tracking algorithm errors and fluctuations in the receiving channel, beam pointing may deviate.

[0004] Currently, C-band and Ku-band satellites in geostationary orbit are densely distributed with longitude intervals of less than 0.5°. In this context, if the antenna beam deflects due to the aforementioned reasons, and after deflection points to a neighboring satellite approximately 0.5° away from the target satellite, and the beacon frequency of this neighboring satellite is the same as that of the target satellite, the antenna system may mistrack to the neighboring satellite, leading to channel interruption and affecting the normal operation of the system. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a method for preventing mistracking of adjacent geosynchronous orbit satellites using a multi-beam antenna. Taking into account the characteristic of multiple independent feed elements in a dual-focus multi-beam antenna mounted on a feed track via movable trolleys, a high-precision magnetic grating ruler is installed along the feed track, and a magnetic grating reading head is installed on the feed trolley to measure the absolute position of the feed trolley on the feed track. Based on the information of the satellite to be tracked, the theoretical position of its corresponding feed element on the feed track is determined. Based on the absolute and theoretical positions, the feed element is controlled to move to the theoretical position, and then the AGC level is used to finally determine the position of the feed element, thus achieving accurate tracking of the satellite to be tracked.

[0006] The technical solution of this invention is as follows:

[0007] A method for preventing mistracking of adjacent geostationary orbit satellites using a multi-beam antenna includes the following steps:

[0008] Step 1: A magnetic scale is installed on the feed track of the multi-beam antenna system along the direction of feed trolley movement, and a magnetic scale reading head is installed on the feed trolley to read the magnetic scale and realize the absolute position measurement of the feed trolley on the feed track; the accuracy value of the magnetic scale is less than the corresponding distance of 0.25° longitude interval on the feed track in geostationary orbit.

[0009] Step 2: Based on the theoretical elevation angle of the multi-beam antenna system aligned with the geostationary orbit satellite to be tracked. Determine the theoretical position of the feed source on the feed source track, and control the feed source trolley to move to the theoretical position;

[0010] Step 3: After the feed trolley moves to the theoretical position, control the feed trolley to move within a local range of the theoretical position, and determine whether the feed is aligned with the satellite by the AGC level fed back by the step tracking receiver; after aligning with the satellite, continue to track the satellite.

[0011] Furthermore, in step 1, the corresponding distance on the feed orbit for a 0.25° longitude interval in geostationary orbit is obtained through the following process:

[0012] Using the theoretical longitude of the nadir point of the geostationary satellite to be tracked and the latitude and longitude of the ground station of the multi-beam antenna system, according to the formula...

[0013]

[0014] The theoretical elevation angle of the multi-beam antenna system aligned with the geostationary orbit satellite to be tracked is obtained. ,in The equatorial radius of the Earth. The radius of the geosynchronous orbit. For the latitude of the ground station of the multi-beam antenna system, This represents the difference in longitude between the ground station's longitude and the theoretical longitude of the satellite's nadir point.

[0015] Substituting the longitude difference by 0.25° into the above formula, we obtain the adjusted pitch angle. The calculated pitch angle is then compared to the theoretical pitch angle. pitch angle difference between According to the formula The calculated distances on the feed orbit corresponding to a 0.25° longitude interval in geostationary orbit are obtained. ,in The radius of curvature of the feed track is denoted as .

[0016] Furthermore, in step 2, an incremental PID algorithm is used to control the feed trolley to move to the theoretical position:

[0017]

[0018] in This is the proportionality coefficient. The coefficient of the integral term, The coefficients of the differential term, This is the current error value. To control the increment of quantity.

[0019] Furthermore, select PID parameters for different stages based on the error range:

[0020]

[0022] Furthermore, step 3 employs an optimized step tracking method, specifically:

[0023] The relationship between the electric field strength and the feed location is fitted using a quadratic function:

[0024]

[0025] The feed trolley moves according to a set step size, thereby respectively... Location acquisition yields corresponding field strength According to the formula:

[0026]

[0027] Solve for the coefficients:

[0028]

[0029]

[0030] Differentiating the quadratic function yields the point of maximum value:

[0031] ,

[0032] Will and Substitution

[0033]

[0034] This adjustment is completed, where K is the initial step size; and according to and Interpolation yields a new step size:

[0035]

[0036] Then, a new step size is used to move the feed trolley until it finally moves to the optimal tracking position.

[0037] Furthermore, the initial setting step size K is set to 1 / 10 of the half beamwidth.

[0038] Beneficial effects

[0039] This invention proposes a method for preventing mistracking of adjacent geostationary orbit satellites using a multi-beam antenna. Addressing the issue that during multi-beam antenna tracking of geostationary orbit satellites, beam deflection can occur due to satellite drift, tracking algorithms, and receiver channel fluctuations, sometimes resulting in the deflected beam pointing towards a neighboring satellite within a 0.5-degree interval, leading to mistracking. This method solves the problem by installing a magnetic scale along the feed trolley's running direction on the feed track of the multi-beam antenna system. This measures the absolute position of the feed trolley on the feed track arc and, based on the information of the satellite to be tracked, determines the theoretical position of its corresponding feed element on the feed track. After controlling the feed element to move to the theoretical position based on the absolute and theoretical positions, an optimized step-tracking method is used to finally determine the feed element's position, achieving accurate tracking of the satellite.

[0040] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0042] Figure 1 Schematic diagram of a multi-beam antenna;

[0043] Figure 2 Step tracking is a traditional algorithm for tracking data;

[0044] Figure 3 Step tracking optimization algorithm for tracking data. Detailed Implementation

[0045] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0046] The dual-focus multi-beam antenna system used in this embodiment has a main reflector size of 18 meters × 18 meters and has 8 independent feed elements. Each feed element is installed on a movable trolley. The trolley is controlled by an X-direction motor to control the movement of the feed element on the feed track. The feed track is an arc track to meet the requirement of multiple feed elements simultaneously tracking geostationary satellites.

[0047] As described in the background section, C-band and Ku-band satellites in geostationary orbit are currently densely distributed with longitude intervals of less than 0.5°. In this context, if the antenna beam deflects due to the aforementioned reasons and points towards a neighboring satellite approximately 0.5° away from the target satellite, and the beacon frequency of this neighboring satellite is the same as that of the target satellite, the antenna system may mistrack to the neighboring satellite, leading to channel interruption and affecting the normal operation of the system. To address this problem, this embodiment proposes a method for preventing mistracking of adjacent geostationary orbit satellites using a multi-beam antenna, specifically including the following steps:

[0048] Step 1: A magnetic scale is installed on the feed track of the multi-beam antenna system along the direction of the feed trolley's movement, and a magnetic scale reading head is installed on the feed trolley to read the magnetic scale and realize the absolute position measurement of the feed trolley on the feed track; the accuracy value of the magnetic scale is less than the corresponding distance of 0.25° longitude interval on the feed track in geostationary orbit.

[0049] During the initial construction of the multi-beam antenna system, the zero point of the magnetic grating ruler set on the feed track is calibrated. The absolute distance obtained by reading the magnetic grating ruler using the magnetic grating reading head is the distance relative to the zero point position of the magnetic grating ruler.

[0050] The corresponding distance of a 0.25° longitude interval in geostationary orbit on the feed orbit is obtained through the following process:

[0051] Using the theoretical longitude of the nadir point of the geostationary satellite to be tracked and the latitude and longitude of the ground station of the multi-beam antenna system, according to the formula...

[0052]

[0053] The theoretical elevation angle of the multi-beam antenna system aligned with the geostationary orbit satellite to be tracked is obtained. ,in The equatorial radius of the Earth. The radius of the geosynchronous orbit. For the latitude of the ground station of the multi-beam antenna system, This represents the difference in longitude between the ground station's longitude and the theoretical longitude of the satellite's nadir point.

[0054] Since a 0.25° longitude interval can be represented as a 0.25° change in longitude difference, the adjusted pitch angle is calculated by substituting the changed longitude difference into the above formula. The adjusted pitch angle is then compared to the theoretical pitch angle. pitch angle difference between According to the formula The calculated distances on the feed orbit corresponding to a 0.25° longitude interval in geostationary orbit are obtained. ,in The radius of curvature of the feed track is denoted as .

[0055] In this embodiment, the calculated distance corresponding to a 0.25° longitude interval on the geostationary orbit is approximately 180mm on the feed orbit. The minimum resolution of the magnetic grating ruler used is 1mm, and the measurement accuracy is 0.5%. The length of the magnetic grating ruler used in the multi-beam antenna system is 20 meters, and the overall measurement accuracy is 5mm. The positioning accuracy can meet the requirements for neighboring satellite tracking and judgment.

[0056] Step 2: Based on the theoretical elevation angle of the multi-beam antenna system aligned with the geostationary orbit satellite to be tracked. The theoretical position of the feed source on the feed source track is determined, and the feed source trolley is controlled to move to the theoretical position.

[0057] In this embodiment, the feed trolley movement is achieved by driving motors in the X direction, where the X direction is along the feed track. The X-direction drive motors are domestically produced Dongling 130DNMB2-0003CJBM motors. Each motor is equipped with a 16-bit in-coil and a 17-bit out-of-coil absolute encoder. The relative position of the feed can be determined by calculating the number of motor rotations and the pitch in the X direction, while the absolute position is calibrated by acquiring the actual position of the magnetic scale through the encoding unit.

[0058] In this embodiment, PID control is used to achieve precise control in the X direction, with a control accuracy ≤0.1mm. In motion control, the characteristics of the motor must be considered. Excessive motor start-up frequency will cause motor seizure; rapid speed changes will cause step loss or oscillation; and excessively rapid motor termination speed will cause overtravel or overshoot. To avoid step loss, impact, oscillation, or overtravel during start-up or shutdown, and to ensure smooth operation, an incremental PID algorithm is used.

[0059]

[0060] in This is the proportionality coefficient. The coefficient of the integral term, The coefficients of the differential term, This is the current error value. To control the increment of the variable; and to select PID parameters for different stages according to the error range to ensure stable and accurate positioning in the X direction, as shown in Table 1:

[0061] Table 1: PID parameters for each stage of multi-beam antenna feed control

[0062]

[0063] Step 3: After the feed trolley moves to the theoretical position, control the feed trolley to move within a local range of the theoretical position, and determine whether the feed is aligned with the satellite by the AGC level fed back by the step tracking receiver; after aligning with the satellite, continue to track the satellite.

[0064] After the feed trolley is moved to the theoretical position, a step tracking algorithm is used to achieve stable tracking of the multi-beam feed. Step tracking is a tracking method that drives the antenna to rotate according to a corresponding algorithm, thereby gradually approaching the point of strongest satellite field strength signal. When the antenna finds and aligns with the location of the maximum satellite field strength signal, the antenna enters a stable tracking state. When the antenna deviates from the location of the maximum satellite field strength due to various factors, the antenna will start a new round of step tracking.

[0065] Traditional parabolic antenna step tracking systems employ a "hill-climbing" step tracking algorithm, determining the next step direction based on the different AGC values ​​received after two steps. However, for multi-beam antenna systems with eight feeds installed simultaneously in the X direction, adjacent feeds face the risk of collision during step tracking. Therefore, the step tracking algorithm needs optimization and improvement. Considering that the main reflector of the antenna remains stationary in a multi-beam antenna system, the further the feeds deviate from the main reflector, the less pronounced the sidelobes become. Therefore, this embodiment proposes an optimized step tracking method:

[0066] The relationship between the electric field strength and the feed location is fitted using a quadratic function:

[0067]

[0068] The feed trolley moves according to a set step size, thereby respectively... Location acquisition yields corresponding field strength According to the formula:

[0069]

[0070] Solve for the coefficients:

[0071]

[0072]

[0073] Differentiating the quadratic function yields the point of maximum value:

[0074] ,

[0075] Will and Substitution

[0076]

[0077] This adjustment is completed, where K is the initial step size, taken as 1 / 10 of the half-beamwidth; and according to... and Interpolation yields a new step size:

[0078]

[0079] Then, a new step size is used to move the feed trolley until it finally moves to the optimal tracking position.

[0080] Compared to the traditional step tracking algorithm, the optimized step tracking algorithm described above, combined with the characteristics of a multi-beam antenna system where the main reflector of the antenna remains stationary and the side lobes become less prominent as the feed source deviates from the main reflector, approximates the field strength and position as a quadratic curve. This can reduce the number of "search" steps and avoid the probability of collisions between adjacent feed sources on the X-axis.

[0081] In this embodiment, the data obtained using the optimized step tracking algorithm is recorded, as shown in Table 2. The calculated tracking accuracy of 0.009° meets the requirement of one-tenth of the beamwidth. Therefore, the tracking accuracy meets the requirements.

[0082] Table 2 Test Records of the Step Tracking Optimization Algorithm

[0083]

[0084] However, when using the traditional fixed-step tracking method to track the same satellite, such as... Figure 2 As shown, step tracking controls the antenna position by the trend of signal level changes between the previous and next steps. Because the top of the curve is relatively flat, the exact position of the top cannot be determined. It will reach a steady state near the maximum value within one step. Through optimization, the maximum value point is interpolated. The interpolation equation is significantly affected by the receiver feedback AGC voltage. Figure 3 As can be seen, the maximum value falls within 3dB, and the maximum value point can be found quickly and stably.

[0085] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for false track prevention for adjacent geosynchronous orbit satellites for a multi-beam antenna, characterized by: The method comprises the following steps: Step 1: A magnetic grating ruler is installed on the feed track of the multi-beam antenna system along the direction of the feed trolley movement, and a magnetic grating reading head is installed on the feed trolley to read the magnetic grating ruler and realize absolute position measurement of the feed trolley on the feed track; the accuracy value of the magnetic grating ruler is less than the corresponding distance of 0.25° longitude interval on the geostationary orbit on the feed track; Step 2: determining a theoretical elevation angle of a multi-beam antenna system to align with a geosynchronous orbit satellite to be tracked determining a theoretical position of the feed on the feed orbit, and controlling movement of the feed carriage to said theoretical position; Step 3: After the feed trolley moves to the theoretical position, the feed trolley is controlled to move within a local range of the theoretical position, and whether the feed is aligned with the satellite is judged through the AGC level feedback of the step tracking receiver; the satellite is continuously tracked after being aligned with the satellite.

2. The method for false tracking prevention of adjacent geosynchronous orbit satellites for a multi-beam antenna according to claim 1, wherein: In step 1, the corresponding distance of 0.25° longitude interval on the geostationary orbit on the feed track is obtained through the following process: The theoretical longitude of the satellite down-point to be tracked, the longitude and latitude of the ground station of the multi-beam antenna system, and the formula are used to obtain the corresponding distance of 0.25° longitude interval on the geostationary orbit on the feed track. Obtaining a theoretical elevation angle for a multi-beam antenna system to align with a geosynchronous orbit satellite to be tracked wherein is the equatorial radius of the Earth, is the geosynchronous orbit radius, is the latitude of the ground station of the multi-beam antenna system, is the longitude difference between the longitude of the ground station and the theoretical longitude of the subsatellite point. Substituting the longitude difference by 0.25° into the above formula, we obtain the adjusted pitch angle. The calculated pitch angle is then compared to the theoretical pitch angle. pitch angle difference between According to the formula The calculated distances on the feed orbit corresponding to a 0.25° longitude interval in geostationary orbit are obtained. ,in The radius of curvature of the feed track is denoted as .

3. The method of claim 1, wherein the method is implemented by a geosynchronous satellite. In step 2, the PID algorithm is used to control the feed trolley to move to the theoretical position: wherein is a proportional term coefficient, is an integral term coefficient, is a derivative term coefficient, is a current error value, is a control amount increment.

4. The method of claim 3, wherein the method is implemented by a geosynchronous satellite. According to the error interval, the PID parameters in different stages are selected: 。 5. The method of claim 1, wherein the method is implemented by a geosynchronous satellite. In step 3, the optimized step tracking method is used, and the specific method is as follows: The relationship between the field strength and the feed position is fitted by using a quadratic function: The feed carriage is moved according to a set step length, so that the corresponding field strength is obtained at the positions According to the formula: The coefficients are solved: The maximum point position of the quadratic function is obtained by differentiation: ， #imgpt32# and #imgpt33# are substituted into #imgpt34# to obtain The adjustment is completed, wherein K is the initial setting step length; and a new step length is obtained by interpolation according to #imgpt35# and #imgpt36#: #imgpt37# Then, the new step length is used to move the feed trolley until the optimal tracking position is finally reached. The initial setting step length K is 1 / 10 of the half-beam width.

6. The method of claim 5, wherein the method is implemented by a geosynchronous satellite. ​

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