An Automatic Compensation Method for Pointing Error of One-Dimensional Phased Array Antenna

Abstract

The present invention provides an automatic compensation method for the pointing error of a one-dimensional phased array antenna. Aiming at the causes of the pointing error of the phased array antenna and the characteristics of the antenna pointing error, the pointing error of the one-dimensional phased array antenna is reduced to within the specified index. Moreover, the null points at different frequencies can be adjusted together, and the time and personnel input for correcting the pointing error are saved. The present invention is based on a one-dimensional phased array radar system. The present invention reduces the pointing error of all phased array antennas by about 10 times to meet the index requirements, and can also adjust the null points at different frequencies together. With a high degree of automated programming, the pointing error correction process does not require manual operation, is suitable for large-scale pointing correction work, and saves the time and personnel input for correcting the pointing error at the same time.

Description

Technical Field

[0001] The present invention relates to the field of radar angle measurement, and can be used for automatic compensation of the pointing error of a one-dimensional phased array antenna, and relates to a method for correcting the pointing accuracy of a high-precision narrow-beam secondary radar. Background Art

[0002] With the rapid development of space technology and radar technology, the requirements for the search and tracking capabilities of antennas are getting higher and higher, and the angle measurement accuracy is an important technical index. The beam pointing accuracy of a phased array antenna has a very important impact on the angle measurement accuracy of a radar system.

[0003] There are many factors affecting the phased array pointing accuracy. For example: the amplitude-phase error of the array surface caused by the position error of the radiation unit, the phase error caused by the quantization error of the digital phase shifter, the physical structure and installation position error between TR units, and the phase error of the array surface caused by the additional phase modulation when adjusting the attenuator, and the amplitude-phase error caused by the uneven temperature of the antenna array surface. In the process of obtaining the antenna pointing error compensation value, all factors affecting the antenna pointing error must be considered. A phased array antenna is a very large and complex system, and it is difficult to strictly distinguish the reasons for the pointing error. Similarly, it is also difficult to physically model the various factors affecting the pointing error and calculate the theoretical values of the various influencing factors.

[0004] Since the physical structures, processes, and installation positions of each phased array antenna cannot be absolutely the same. Therefore, the pointing error characteristics of a phased array antenna are that the pointing error characteristics of different phased array antenna surfaces are different, and when the same phased array antenna surface operates at different frequencies, the pointing error is also different. The pointing error of one antenna surface cannot be reused for other phased array antenna surfaces through theoretical calculations, analogies, etc. This makes the pointing correction work have a large workload and a heavy task. The current pointing correction work not only wastes time but also requires human participation.

[0005] How to correct the pointing error of a phased array antenna efficiently and with high precision has always attracted the attention of relevant researchers. Summary of the Invention

[0006] In order to overcome the deficiencies of the prior art, the present invention provides a method for automatically compensating the pointing error of a one-dimensional phased array antenna. Aiming at the use requirements of phased array antenna pointing error compensation described in the background and the deficiencies of the current technology, the present invention proposes a method for automatically compensating the pointing error of a phased array antenna, realizes the unmanned design of the automatic compensation process, and formulates an efficient pointing error compensation scheme. This scheme can not only reduce the pointing error of the one-dimensional phased array antenna within the index, but also adjust the zeros at different frequencies together, and can save the time and personnel investment for correcting the pointing error.

[0007] Based on the one-dimensional phased array radar system, aiming at the causes of the pointing error of the phased array antenna and the characteristics of the antenna pointing error, the present invention proposes an automatic compensation method for the pointing error of the one-dimensional phased array antenna.

[0008] The technical solution adopted by the present invention to solve its technical problems includes the following steps:

[0009] Step 1: Build an automatic compensation system for the beam pointing error of the one-dimensional active phased array radar. The automatic compensation system consists of the device under test, a signal source, and an angle measurement central unit;

[0010] The device under test consists of four one-dimensional active phased array surfaces to be pointed and compensated. The active phased array surfaces include surface A, surface B, surface C, and surface D. The four surfaces are all fixed on the turntable flat plate. The distance from the center of each surface to the turntable center O is the same, all being R. The center of each surface is the mechanical zero position. Moreover, the connection line of the mechanical zero positions of surface A and surface C is perpendicular to the connection line of the mechanical zero positions of surface B and surface D, and both pass through the turntable center O. The azimuth rotation accuracy of the selected turntable is higher than the required surface pointing accuracy, and the theoretical position of the beam pointing of the surface under test is simulated through the turntable;

[0011] The surfaces are electrically scanned in the azimuth direction. The azimuth scanning range of each surface is ±45°. The four surfaces of the device under test cover 360° in the azimuth direction. The normal direction of surface A is the azimuth angle of 0°, and the clockwise direction is the angle increasing direction. Therefore, the azimuth scanning range of surface A is from -45° to 45°, the azimuth scanning range of surface B is from 45° to 135°, the azimuth scanning range of surface C is from 135° to 225°, and the azimuth scanning range of surface D is from 225° to 315°;

[0012] The signal source device is fixed within the effective range with an open field of view and no obstruction, and cooperates with the device under test to complete the interrogation and response work of the secondary radar, providing the target direction for the four surfaces A, B, C, and D of the device under test. The radiation surface E in the signal source is directly opposite to the turntable center O;

[0013] The angle measurement central unit analyzes the radar echo data to obtain the tracking angle α of the device under test tracking the signal source target, that is, the current surface beam pointing angle; the angle value α of the turntable is read by the angle measurement central unit from the turntable data line between the angle measurement central unit and the turntable 真 ; at the same time, the angle measurement central unit controls the rotation of the turntable in real time through the turntable control line;

[0014] Step 2: The centrifugal azimuth error caused by the rotation of the turntable needs to be eliminated through modeling;

[0015] L is the measured value of the distance between the surface and the signal source. The azimuth angle of the signal source relative to the device under test is α, and the azimuth angle measured by the angle measurement system is θ. α = θ - β, where β is the centrifugal azimuth error caused by the distance between the antenna surface and the turntable center. Therefore, the target azimuth angle α after eliminating the centrifugal azimuth error is as follows:

[0016]

[0017] After eliminating the centrifugal azimuth error, the obtained angle measurement value is the actual angle measurement value α of the array surface. By comparing the actual angle value α at the current position with the beam pointing angle value α simulated by the turntable 真 , the compensation value e corresponding to the current pointing angle is obtained as e = α 真 -α;

[0018] Step 3: Adopt the step-by-step PID method to gradually adjust the beam pointing parameters, accumulate the pointing adjustment values, and automatically obtain the pointing error value corresponding to the current beam pointing angle;

[0019] There is a deviation e = α between the filtered output angle α and the true beam pointing α simulated by the turntable 真 The deviation is connected to the PID controller. Before calling the PID controller, first judge the set value e, and then use the result of this function as the set value for the PID controller. By building a closed-loop system for automatically obtaining the pointing error, the pointing error value that needs to be compensated for the current pointing angle is obtained; the essence of this step-by-step method is to perform a smooth change process on the set value to prevent fluctuations in the angle measurement system caused by jumps in the set value; 真

[0020] Step 4: Load the pointing error compensation value and verify the effectiveness of the automatic pointing error compensation;

[0021] According to the current working frequency point i and the beam pointing angle j, search for the automatic compensation value F of the beam pointing error value n , add the obtained current compensation value to the output angle of the monopulse angle measurement system before filtering for pointing error compensation. After filtering, the system angle can be output. At the same time, verify the effectiveness and accuracy of the pointing error compensation method by calculating whether the difference between the beam pointing angle simulated by the turntable and the system output angle is less than the error precision Δ.

[0022] The steps of judgment and compensation in step 3 are as follows:

[0023] Step 3.1: Calculate the difference e = α between the current beam theoretical pointing (turntable angle value) and the filtered output system angle 真 -α;

[0024] ​Step 3.2: Determine the magnitude relationship between the difference e and the error precision Δ. When |e(k)| < Δ, it indicates that the pointing error meets the pointing precision index requirements, and this pointing angle does not require compensation. When |e(k)| ≥ Δ, for e(k) > 0, the compensation value is compensated by doubling the error precision Δ per beat, and then participates in the monopulse angle measurement closed-loop tracking. After n beats, it is measured that the pointing error meets the pointing precision index requirements. At this time, after n beats of compensation, the beam pointing error compensation value α buchang (i, j) = n·Δ, where i represents the current frequency and j represents the current compensation angle; similarly, for e(k) ≤ 0, after m beats of compensation, the beam pointing error compensation value α buchang (i, j) = -m·Δ;

[0025] Step 3.3: Let the turntable stay at an integer angle for several seconds at the current beam pointing angle to ensure that the system can stably track at each frequency point; set the rotation mode of the turntable, with a rotation step of 1° and a rotation range of 0 to 360°. Use Step 3.2 to automatically obtain the pointing error compensation value α buchang (i, j) at the current frequency point, then switch to the next frequency point i + 1 that needs to obtain the compensation value, repeat Step 3.2 to complete the pointing error compensation for all frequency points, and then the angle measurement central unit commands the turntable upper computer to turn to the next angle j + 1 to obtain the pointing error compensation values corresponding to each frequency point at each integer angle N represents the number of frequency points;

[0026] Step 3.4: The compensation values between integer degrees are used to calculate the compensation data corresponding to each point through linear interpolation. The linear interpolation formula is as follows: Finally, the obtained azimuth pointing error compensation data F n for each linear array, F n is an N*M matrix, where N represents the number of frequency points and M represents the number of angles. When linear interpolation is applied to the compensation of the pointing error of the phased array antenna, only integer angles need to be tested, and the pointing errors of other angles are interpolated and calculated based on the measured pointing errors, reducing the workload of testing.

[0027] The beneficial effect of the present invention lies in the proposed automatic compensation method for the pointing error of the one-dimensional phased array antenna. Verified by a certain type of actual installed radar, it can reduce the pointing error of all phased array antennas of this type by about 10 times to meet the index requirements, and can also adjust the null points at different frequencies together. With a high degree of automation programming, the pointing error correction process does not require manual operation, is suitable for large-scale pointing correction work, and saves the time and personnel input for correcting the pointing error. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the composition diagram of the automatic compensation system for the beam pointing error of the one-dimensional active phased array radar of the present invention.

[0029] Figure 2 It is a schematic diagram of the centrifugal azimuth error model of the present invention.

[0030] Figure 3 It is a schematic diagram of the automatic compensation principle of the beam pointing error of the one-dimensional active phased array radar of the present invention.

[0031] Figure 4 It is a flowchart of the automatic compensation of the beam pointing error of the present invention.

[0032] Figure 5 It is a compensation position diagram of the beam pointing error value of the present invention. Specific implementation mode

[0033] The present invention will be further described below in conjunction with the drawings and embodiments.

[0034] Step 1: Build an automatic compensation system for the beam pointing error of the one-dimensional active phased array radar. The automatic compensation system consists of the device under test, a signal source, and an angle measurement central unit.

[0035] Step 2: Given that in the test site, the signal source and the device under test cannot be far enough apart, during the measurement of the azimuth angle of the device under test, the error caused by the distance between the array surface and the center of the turntable cannot be ignored. The centrifugal azimuth error caused by the rotation of the turntable is eliminated through modeling.

[0036] Step 3: Adopt the step-by-step PID method to gradually adjust the beam pointing parameters, accumulate the pointing adjustment values, and automatically obtain the pointing error value corresponding to the current beam pointing angle.

[0037] Step 4: Load the pointing error compensation value and verify the effectiveness of the automatic compensation of the pointing error.

[0038] Based on the one-dimensional phased array radar system, the present invention proposes an automatic compensation method for the pointing error of the one-dimensional phased array antenna in view of the causes of the phased array antenna pointing error and the characteristics of the antenna pointing error.

[0039] Step 1: Build an automatic compensation system for the beam pointing error of the one-dimensional active phased array radar. The automatic compensation system consists of the device under test, a signal source, and an angle measurement central unit.

[0040] The device under test consists of four one-dimensional active phased array surfaces to be pointed and compensated. The active phased array surfaces include surface A, surface B, surface C, and surface D. The four surfaces are all fixed on the turntable flat plate. The distance from the center (mechanical zero position) of each surface to the turntable center O is the same, which is R. Moreover, the connection line of the mechanical zero positions of surface A and surface C is perpendicular to the connection line of the mechanical zero positions of surface B and surface D, and both pass through the turntable center O. The selected azimuth rotation accuracy of the turntable is higher than the required surface pointing accuracy. The turntable is used to simulate the theoretical position of the beam pointing of the surface under test;

[0041] The surfaces are electrically scanned in the azimuth direction. The azimuth scanning range of each surface is ±45°. The four surfaces of the device under test cover 360° in the azimuth direction. The normal direction of surface A is the azimuth angle of 0°, and the clockwise direction is the angle increasing direction. Therefore, the azimuth scanning range of surface A is from -45° to 45°, the azimuth scanning range of surface B is from 45° to 135°, the azimuth scanning range of surface C is from 135° to 225°, and the azimuth scanning range of surface D is from 225° to 315°.

[0042] The signal source device is fixed within the effective range with an open field of view and no obstruction, and cooperates with the device under test to complete the interrogation and response work of the secondary radar, providing the target direction for the four surfaces A, B, C, and D of the device under test. The radiation surface E in the signal source is directly facing the turntable center O;

[0043] The angle measurement central unit analyzes the radar echo data to obtain the tracking angle α of the device under test tracking the signal source target, that is, the current surface beam pointing angle; the angle measurement central unit reads the angle value α of the turntable through the turntable data line between the angle measurement central unit and the turntable 真 ; at the same time, the angle measurement central unit controls the rotation of the turntable in real time through the turntable control line;

[0044] Step 2: Given that within the test site, the signal source and the device under test cannot be far enough apart. During the measurement of the azimuth angle of the device under test, the angle measurement error caused by the distance between the surface and the turntable center cannot be ignored. The centrifugal azimuth error caused by the rotation of the turntable needs to be eliminated through modeling.

[0045] The schematic diagram of the centrifugal azimuth error model is as Figure 2 shown. The value of the turntable centrifugal azimuth error is related to the distance r between the surface and the turntable center O, and is also related to the distance R between the signal source and the turntable center O. L is the measured value of the distance between the surface and the signal source; the azimuth angle of the signal source relative to the device under test is α, but the azimuth angle measured by the angle measurement system is θ, α = θ - β, and β is the centrifugal azimuth error caused by the distance between the antenna surface and the turntable center Therefore, the target azimuth angle α after eliminating the centrifugal azimuth error is:

[0046] After eliminating the centrifugal azimuth error, the obtained angle measurement value is the actual angle measurement value α of the array surface. By comparing the actual angle value α at the current position with the beam pointing angle value α simulated by the turntable 真 , the compensation value e corresponding to the current pointing angle is obtained as e = α 真 - α.

[0047] Step 3: Adopt the step-by-step PID method to gradually adjust the beam pointing parameters, accumulate the pointing adjustment values, and automatically obtain the pointing error value corresponding to the current beam pointing angle;

[0048] The schematic diagram of the automatic compensation for the beam pointing error of the one-dimensional active phased array radar is shown in Figure 3 . Due to the existence of the pointing error of the linear array, there is a deviation e = α between the output angle α after filtering and the true beam pointing α simulated by the turntable 真 - α. The deviation is connected to the PID controller. Before calling the PID controller, first judge the set value e, and then use the result of this function as the set value for the PID controller. Through the built closed-loop system for automatically obtaining the pointing error, the pointing error value that needs to be compensated for the current pointing angle is obtained; the essence of this step-by-step method is to perform a smooth change process on the set value to prevent fluctuations in the angle measurement system caused by jumps in the set value. The specific flowchart of judgment and compensation is shown in 真 . Figure 4 .

[0049] Step 3.1: Calculate the difference e = α between the theoretical pointing of the current beam (turntable angle value) and the system angle output after filtering 真 - α;

[0050] Step 3.2: Judge the size of the difference e and the error precision Δ. When |e(k)| < Δ, the pointing error meets the requirements of the pointing precision index, and this pointing angle does not need to be compensated; when |e(k)| ≥ Δ, for e(k) > 0, the compensation value is compensated by doubling the error precision Δ per beat, and then participates in the monopulse angle measurement closed-loop tracking. After n beats, the measured pointing error meets the requirements of the pointing precision index. At this time, after n beats of compensation, the beam pointing error compensation value α buchang (i, j) = n·Δ, where i represents the current frequency and j represents the current compensation angle; similarly, for e(k) ≤ 0, after m beats of compensation, the beam pointing error compensation value α buchang (i, j) = -m·Δ;

[0051] Step 3.3: Let the turntable stay at an integer angle for several seconds. At the current beam pointing angle, ensure that the system can stably track at each frequency point; set the rotation mode of the turntable, the rotation step is 1°, and the rotation range is 0 - 360°. Use Step 3.2 to automatically obtain the pointing error compensation value α at the current frequency point buchang(i, j), then switch to the next frequency point i + 1 for which the compensation value needs to be obtained, repeat step 3.2, complete the pointing error compensation for all frequency points, and then the angle measurement central unit commands the upper computer of the turntable to turn to the next angle j + 1. Obtain the pointing error compensation values corresponding to each frequency point at each integer angle. N represents the number of frequency points;

[0052] Step 3.4: The compensation values between integer degrees are used to find the compensation data corresponding to each point through linear interpolation. The linear interpolation formula is as follows: Finally, the obtained azimuth pointing error compensation data F for each linear array n , F n is an N * M matrix, where N represents the number of frequency points and M represents the number of angles. When linear interpolation is applied to the compensation of the phased array antenna pointing error, only the integer angles need to be tested, and the pointing errors of other angles are interpolated and calculated based on the measured pointing errors, reducing the workload of testing.

[0053] Step 4: Load the pointing error compensation value and verify the effectiveness of the automatic pointing error compensation.

[0054] According to the current operating frequency point i and the beam pointing angle j, find the automatic compensation value F of the beam pointing error value n , and add the found current compensation value to the output angle of the monopulse angle measurement system before filtering for pointing error compensation. As Figure 5 shown, after filtering, the system angle can be output. At the same time, verify the effectiveness and accuracy of the pointing error compensation method by calculating whether the difference between the beam pointing angle simulated by the turntable and the system output angle is less than the error precision Δ.

Claims

1. An automatic compensation method for pointing error of a one-dimensional phased array antenna, characterized in that It includes the following steps: Step 1: Build an automatic compensation system for the beam pointing error of a one-dimensional active phased array radar. The automatic compensation system consists of a device under test, a signal source, and an angle measurement central unit; The device under test consists of four one-dimensional active phased array surfaces to be pointed and compensated. The active phased array surfaces include surface A, surface B, surface C, and surface D. The four surfaces are all fixed on the turntable flat plate. The distance from the center of each surface to the turntable center O is the same, which is R. The center of each surface is the mechanical zero position. Moreover, the connection line of the mechanical zero positions of surface A and surface C is perpendicular to the connection line of the mechanical zero positions of surface B and surface D, and both pass through the turntable center O. The selected turntable has an azimuth rotation accuracy higher than the required surface pointing accuracy, and the theoretical position of the beam pointing of the measured surface is simulated through the turntable; The surfaces are in an electrically scanned mode in the azimuth direction. The azimuth scanning range of each surface is ±45°. The four surfaces of the device under test cover 360° in the azimuth direction. The normal direction of surface A is the azimuth angle of 0°, and the clockwise direction is the angle increasing direction. Therefore, the azimuth scanning range of surface A is from -45° to 45°, the azimuth scanning range of surface B is from 45° to 135°, the azimuth scanning range of surface C is from 135° to 225°, and the azimuth scanning range of surface D is from 225° to 315°; The signal source device is fixed within the effective range with an open field of view and no obstruction, and cooperates with the device under test to complete the interrogation and response work of the secondary radar, providing the target direction for the four surfaces A, B, C, and D of the device under test. The radiation surface E in the signal source faces the turntable center O; The angle measurement central unit analyzes the radar echo data to obtain the tracking angle α of the device under test tracking the signal source target, that is, the current front beam pointing angle; the angle measurement central unit reads the angle value α of the turntable through the turntable data line between the angle measurement central unit and the turntable. 真 At the same time, the angle measurement central unit controls the rotation of the turntable in real time through the turntable control line; Step 2: The centrifugal azimuth error caused by the rotation of the turntable needs to be eliminated through modeling; L is the measured value of the distance between the array face and the signal source. The azimuth angle of the signal source with respect to the device under test is α, and the azimuth angle measured by the angle measurement system is θ. α = θ - β, where β is the centrifugal azimuth error caused by the distance between the antenna array face and the center of the turntable. Therefore, the target azimuth angle α after eliminating the centrifugal azimuth error is: After eliminating the centrifugal azimuth error, the obtained angle measurement value is the actual angle measurement value α of the array surface. By comparing the actual angle value α at the current position with the beam pointing angle value α simulated by the turntable 真 , the compensation value e corresponding to the current pointing angle is obtained as e = α 真 - α; Step 3: Adopt the stepwise PID method to gradually adjust the beam pointing parameters, accumulate the pointing adjustment values, and automatically obtain the pointing error value corresponding to the current beam pointing angle; The output angle α after filtering and the true beam pointing α simulated by the turntable 真 There is a deviation e = α 真 -α. The deviation is connected to the PID controller. Before calling the PID controller, the set value e is first judged, and then the result of this function is used as the set value for the PID controller. By building a closed-loop system for automatically obtaining the pointing error, the pointing error value that needs to be compensated for the current pointing angle is obtained; the essence of the stepped PID method is to perform a smooth change process on the set value to prevent fluctuations in the angle measurement system caused by jumps in the set value; Step 4: Load the pointing error compensation value and verify the effectiveness of the automatic compensation of the pointing error; According to the current working frequency point i and the beam pointing angle j, look up the automatic compensation value F of the beam pointing error value n , add the obtained current compensation value to the output angle of the monopulse angle measurement system before filtering for pointing error compensation. After filtering, the system angle can be output. At the same time, verify the effectiveness and accuracy of the pointing error compensation method by calculating whether the difference between the beam pointing angle simulated by the turntable and the system output angle is less than the error accuracy Δ.

2. The automatic compensation method for the pointing error of a one-dimensional phased array antenna according to claim 1, characterized in that: The steps of judgment and compensation in step 3 are as follows: Step 3.1: Calculate the system angular difference e = α 真 - α between the current beam's theoretical pointing and the filtered output; Step 3.2: Judge the magnitude of the difference e and the error accuracy Δ. When |e(k)| < Δ, the pointing error meets the requirements of the pointing accuracy index, and the current surface beam pointing angle does not need to be compensated; when |e(k)| ≥ Δ, for e(k) > 0, the compensation value is compensated by doubling the error accuracy Δ per beat, and then participates in the monopulse angle measurement closed-loop tracking. After n beats, it is measured that the pointing error meets the requirements of the pointing accuracy index. At this time, after n beats of compensation, the beam pointing error compensation value α buchang (i, j) = -n·Δ, where i represents the current frequency and j represents the current compensation angle; similarly, for e(k) ≤ 0, after m beats of compensation, the beam pointing error compensation value α buchang (i, j) = -m·Δ; Step 3.3: Let the turntable stay at an integer angle for several seconds. At the current beam pointing angle, ensure that the system can stably track at each frequency point. Set the rotation mode of the turntable with a rotation step of 1° and a rotation range of 0 to 360°. Use the value of the pointing error compensation α obtained automatically in Step 3.2 buchang (i, j), then switch to the next frequency point i + 1 for which the compensation value needs to be obtained, repeat Step 3.2 to complete the pointing error compensation for all frequency points. Then, the angle measurement central unit commands the turntable upper computer to turn to the next angle j + 1 to obtain the pointing error compensation values corresponding to each frequency point at each integer angle. N represents the number of frequency points; Step 3.4: The compensation values between integer degrees are used to find the compensation data corresponding to each point through linear interpolation. The linear interpolation formula is as follows: Finally, the azimuth pointing error compensation data F for each linear array is obtained n , F n is an N*M matrix, where N represents the number of frequency points and M represents the number of angles. When linear interpolation is applied to the compensation of the phased array antenna pointing error, only integer angles need to be tested, and the pointing errors of other angles are interpolated and calculated based on the measured pointing errors, reducing the workload of testing.

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