A technology for improving height measurement accuracy based on antenna array calibration

Abstract

The invention relates to a height measurement accuracy improvement technology based on antenna array calibration, which adopts a theodolite, a static level and a dynamic level; the theodolite calibrates the true level, and by using the true level calibrated by the theodolite, the structural error is corrected in the data of the static level; the dynamic level is installed on the array surface, and the theodolite is used to calibrate the system error of the dynamic level. The theodolite of the invention is used to calibrate the true level, and the calibration true value of the theodolite is used to correct the measurement values ​​of the static level and the dynamic level, and the system errors of the static level and the dynamic level can be corrected to a very small level, so that the level accuracy is improved, thereby effectively improving the height measurement accuracy of the radar.

Description

Technical Field

[0001] The present invention relates to the technical field of radar systems, and in particular to a technology for improving height measurement accuracy based on antenna array calibration. Background Art

[0002] Modern warfare requires radar to have three-coordinate function, which can measure the distance, azimuth and elevation of the target, so as to obtain more target information. Altitude measurement is one of the important tactical indicators of three-coordinate radar. The accuracy of target altitude information directly affects the tactical effect of air defense combat command system.

[0003] The radar target height calculation formula is:

[0004]

[0005] Where is the radar antenna height, R is the slant distance from the radar station to the target, β is the elevation angle, and is the equivalent earth radius. The height error can be derived as

[0006]

[0007] In the formula, can be ignored, σ R is the ranging accuracy, σ β is the pitch angle measurement error.

[0008] In summary, the target distance, azimuth, and elevation angle of the three-coordinate radar are directly measured values, while the target height is a secondary measurement value obtained by comprehensively calculating the target distance and elevation angle. Therefore, the factors affecting the accuracy of height measurement mainly include ranging error and elevation angle measurement error. Distance measurement is generally achieved by measuring the time difference between the received echo and the transmitted echo, multiplied by half the speed of light, and the ranging accuracy is relatively high. Angle measurement is generally achieved by sum / difference ratio angle measurement. Due to the wide beam, insensitive angular sensitivity function, poor stability of the measurement platform, etc., the actual angle measurement accuracy is generally worse than the ranging accuracy.

[0009] Mobile vehicle-mounted radar has many advantages such as high mobility, strong position adaptability, and high battlefield survivability, and is one of the important directions of modern radar development. However, vehicle-mounted radar also has the characteristics of complex structure and high requirements on chassis.

[0010] The mobile vehicle-mounted radar uses a mobile vehicle platform, and the hydraulic leveling legs, antenna lifting mechanism and turntable in the servo control system are used to realize the inversion, azimuth rotation and locking of the antenna, so as to realize the azimuth sweep of the antenna array. The antenna lifting mechanism has system errors such as structural installation errors, which will cause the antenna array to have different tilt angles in different azimuths when scanning in azimuth, affecting the radar's height measurement accuracy.

[0011] In summary, height measurement accuracy is an important indicator for evaluating radar performance and an important factor affecting the working ability of radar. Height measurement accuracy is closely related to elevation angle accuracy, and the actual horizontality of the antenna array is closely related to the elevation angle measurement accuracy. Therefore, it is necessary to model a scientific, reasonable and feasible antenna array calibration scheme to eliminate radar system errors and improve height measurement accuracy. Summary of the invention

[0012] In order to solve the existing technical problems, the present invention provides a technology for improving height measurement accuracy based on antenna array calibration.

[0013] The specific contents of the present invention are as follows: a technology for improving the height measurement accuracy based on antenna array calibration, which adopts a theodolite, a static level and a dynamic level; the theodolite calibrates the true horizontality, and by using the true horizontality calibrated by the theodolite, the structural error is corrected in the data of the static level; the theodolite is used to calibrate the system error of the dynamic level, and the dynamic level is installed on the array surface.

[0014] Furthermore, the static level error calibration method includes: the static level is installed on the carrier, and several typical calibration positions are selected to obtain the static level measurement value and the calibration true value at the corresponding position. After correcting the measurement value with the calibration true value, the system error of the static level is corrected, and the system error includes the structural error.

[0015] Furthermore, the static level calibration includes the following steps:

[0016] S11, the antenna is rotated to the maintenance position. In this state, the pitch and roll of the antenna array are measured with a theodolite, marked as -Dx and -Dy;

[0017] S12, the antenna is rotated to the calibration position. In this state, the pitch and roll of the antenna array are measured with a theodolite and marked as Dx and Dy;

[0018] S13, the antenna is rotated to the transport position. In this state, the pitch and roll of the antenna array are measured with a theodolite, marked as Dx and -Dy;

[0019] S14, the antenna is rotated to the reverse transport position. In this state, the pitch and roll of the antenna array are measured with a theodolite, which are marked as -Dx and Dy;

[0020] S15, taking the mean of the four sets of data;

[0021] S16, calculating the difference between the existing data of the static level and the mean value to obtain the correction data of the level;

[0022] S17, after filling the correction data into the main control module, re-leveling.

[0023] Furthermore, the error calibration method of the dynamic level includes: the dynamic level is installed on the array surface, and the calibration of the dynamic level is completed after the calibration of the static level is completed. After selecting several typical calibration positions, the dynamic level measurement value and the calibration true value at the corresponding position are obtained, and after the measurement value is corrected with the calibration true value, the system error of the dynamic level is corrected.

[0024] Furthermore, the dynamic level calibration includes:

[0025] S21, the antenna is rotated to the maintenance position, calibration position, transportation position, and transportation reverse position in steps S11-S14, and the pitch and roll of the array are measured by the theodolite in the corresponding states, which are marked as Dx and Dy;

[0026] S22, at the four angles of step S21, respectively read the dynamic level meter data on the system status table on the terminal interface, marked as DX and DY;

[0027] S23, taking the average of the four groups of measurement data and calculating the difference between the average and the dynamic level data to obtain the correction error;

[0028] S24, record the correction value and compensate it into the back-end processing file.

[0029] Furthermore, after step S17, the antenna horizontality data is re-measured according to steps S11-S17, and it is qualified if the error is less than 0.1 degree.

[0030] The theodolite of the present invention is used to calibrate the true horizontality and utilize the calibration true value of the theodolite to correct the measurement values ​​of the static horizontal meter and the dynamic horizontal meter, so that the system errors of the static horizontal meter and the dynamic horizontal meter can be corrected to a very small level, thereby improving the horizontality accuracy and thus effectively improving the height measurement accuracy of the radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specific implementation of the present invention will be further explained below in conjunction with the accompanying drawings.

[0032] Figure 1 This is a schematic diagram for antenna array calibration;

[0033] Figure 2 This is a schematic diagram for calibration of maintenance positions;

[0034] Figure 3 This is a schematic diagram of calibration position calibration;

[0035] Figure 4 This is a schematic diagram of the transport position calibration;

[0036] Figure 5 It is a schematic diagram of the transport reverse position calibration;

[0037] Figure 6 This is the calibration flow chart for static level instrument;

[0038] Figure 7 This is the calibration flow chart of the dynamic level;

[0039] Figure 8 This is a comparison chart of high-precision measurements before and after array calibration. DETAILED DESCRIPTION

[0040] Combination Figure 1-Figure 8 This embodiment discloses a technique for improving the height measurement accuracy based on antenna array calibration, including the following steps: using a theodolite to calibrate the system errors of a static level and a vehicle structure. The purpose of static level calibration is to correct the structural error in the data of the static level by using the true level calibrated by the theodolite, so as to ensure that the horizontal error of the antenna is relatively small after the antenna vehicle is leveled; using a theodolite to calibrate the system error of a dynamic level.

[0041] Among them, the error calibration method of the static level is as follows: the static level is installed on the carrier, and after selecting several typical calibration positions, the static level measurement value and calibration true value at the corresponding position are obtained. After the calibration true value is used to correct the measurement value, the system error of the static level (including the structural error) can be corrected to a very small level. The error calibration method of the dynamic level is as follows: the dynamic level is installed on the array surface, and the calibration of the dynamic level is completed after the static level calibration is completed. After selecting several typical calibration positions, the dynamic level measurement value and calibration true value at the corresponding position are obtained. After the calibration true value is used to correct the measurement value, the system error of the dynamic level can be corrected to a very small level.

[0042] The technical solution of this embodiment is described in detail below with reference to the accompanying drawings:

[0043] like Figure 1 As shown, the horizontal waveguide of the antenna array is defined as X toward the high-frequency box (i.e., facing the antenna, the direction of human sight), which represents the pitch of the antenna. The upward sight line is a positive angle, which means that the antenna array is tilted downward.

[0044] The horizontal waveguide coaxial transformation of the antenna array is defined as Y towards the load direction, which represents the roll of the antenna. The load is at a positive angle upward relative to the coaxial transformation, which means that the antenna array is tilted to the right.

[0045] The direction from the rear of the vehicle platform to the front of the vehicle is defined as Y', and the front of the vehicle tilting upward is a positive angle;

[0046] Define the direction from the left side of the front of the vehicle to the right side of the front of the vehicle when looking down as X'. The right side of the front of the vehicle is higher than the left side of the front of the vehicle, which is a positive angle.

[0047] Define the X and Y axis directions of the dynamic level to be the same as the antenna array direction.

[0048] Based on the above definition, the implementation process steps are as follows:

[0049] Static level calibration includes the following steps:

[0050] S11, the antenna rotates to Figure 2 Maintenance position (X and Y' directions are opposite, Y and X' directions are opposite), with the normal direction of the maintenance position array as the azimuth zero position, in this state, the pitch and roll of the antenna array are measured with a theodolite, marked as -Dx and -Dy. At this time, the -Dx data matches the Y' data, and the -Dy data matches the X' data.

[0051] S12, the antenna rotates to Figure 3 Calibrate the position (X and Y' directions are the same, Y and X' directions are the same), and use the theodolite to measure the pitch and roll of the antenna array in this state, marked as Dx and Dy. At this time, the Dx data matches the Y' data, and the Dy data matches the X' data.

[0052] S13, the antenna rotates to Figure 4 Transport position (X and X' directions are the same, Y and Y' directions are opposite). In this state, the pitch and roll of the antenna array are measured with a theodolite and marked as Dx and -Dy.

[0053] S14, the antenna rotates to Figure 5 Transport reverse position (X and X' directions are opposite, Y and Y' directions are the same), in this state, use the theodolite to measure the pitch and roll of the antenna array, marked as -Dx and Dy.

[0054] S15, fill in the four sets of data into Table 1 according to the prompts (where δ is the inclination angle of the antenna array, the level meter has a high sensitivity, and it is necessary to wait for it to stabilize before reading the value), and take the average.

[0055] S16, calculating the difference between the existing data of the static level and the mean value to obtain the correction data of the level.

[0056] S17, after filling the correction data into the main control module, re-leveling.

[0057] Re-measure the antenna horizontality data according to steps S11-S17. If the error value is less than 0.1 degree (6 points), it is considered qualified.

[0058] Table 1 Static level data calibration table

[0059]

[0060]

[0061] Dynamic level calibration includes:

[0062] S21, the antenna rotates to Figure 2 , Figure 3, Figure 4 , Figure 5 The position of the array is measured with a theodolite in the corresponding state, and the pitch and roll of the array are marked as Dx and Dy.

[0063] S22, at the four angles of step S21, the dynamic level meter data is read from the system status table on the terminal interface respectively, marked as DX and DY.

[0064] S23, as shown in Table 2, take the average of the four groups of measurement data, and calculate the difference with the dynamic level data to obtain the corrected error.

[0065] S24, record the correction value and compensate it into the back-end processing file.

[0066] Table 2 Dynamic level data calibration table

[0067]

[0068] from Figure 8 From the comparison of the height measurement accuracy before and after the array calibration, it can be seen that the height measurement accuracy is significantly improved after the array calibration, which can reduce the horizontal system error of the radar after calibration and the pitch angle measurement error, so that the height measurement error can be maintained at a level that meets the mission requirements.

[0069] The technology for improving the height measurement accuracy based on antenna array calibration of the present invention has a scientific, reasonable and feasible modeling method, a clear and definite method for testing the radar's ability to work in a complex electromagnetic environment, and a detailed and credible conclusion. By using theodolite, static level and dynamic level to calibrate the antenna array, the method is simple to implement, the effect is obvious and the result is reasonable. The method has obvious application effect in a certain type of intelligence radar, and can effectively correct the structural error of the antenna array in the experiment, improve the horizontality accuracy, and thus effectively improve the radar's height measurement accuracy. The method is easy to promote to other similar products because of its clear principle and simple operation.

[0070] Many specific details are described in the above description to facilitate a full understanding of the present invention. However, the above description is only a preferred embodiment of the present invention. The present invention can be implemented in many other ways different from those described herein, so the present invention is not limited to the specific implementation disclosed above. At the same time, any person familiar with the art can make many possible changes and modifications to the technical solution of the present invention using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A technology for improving height measurement accuracy based on antenna array calibration, characterized in that: Theodolite, static level and dynamic level are used; the theodolite is used to calibrate the true level. By using the true level calibrated by the theodolite, the structural error is corrected in the data of the static level. The dynamic level is installed on the array surface, and the theodolite is used to calibrate the system error of the dynamic level. The static level error calibration method includes: installing the static level on a vehicle, selecting several typical calibration positions, obtaining the static level measurement value and calibration true value at the corresponding position, correcting the measurement value with the calibration true value, and then correcting the system error of the static level, wherein the system error includes the structural error; The error calibration method of the dynamic level includes: the dynamic level is installed on the array surface, the calibration of the dynamic level is completed after the static level calibration is completed, several typical calibration positions are selected, the dynamic level measurement value and calibration true value at the corresponding position are obtained, and the measurement value is corrected with the calibration true value, and then the system error of the dynamic level is corrected.

2. The height measurement accuracy improvement technology based on antenna array calibration according to claim 1 is characterized in that: The static level calibration includes the following steps: S11, the antenna is rotated to the maintenance position. In this state, the pitch and roll of the antenna array are measured with a theodolite, marked as -Dx and -Dy; S12, the antenna is rotated to the calibration position. In this state, the pitch and roll of the antenna array are measured with a theodolite and marked as Dx and Dy; S13, the antenna is rotated to the transport position. In this state, the pitch and roll of the antenna array are measured with a theodolite, marked as Dx and -Dy; S14, the antenna is rotated to the reverse transport position. In this state, the pitch and roll of the antenna array are measured with a theodolite, which are marked as -Dx and Dy; S15, taking the mean of the four groups of data; S16, calculating the difference between the existing data of the static level and the mean value to obtain the correction data of the level; S17, after filling the correction data into the main control module, re-leveling.

3. The technique for improving height measurement accuracy based on antenna array calibration according to claim 1 is characterized in that: Dynamic level calibration includes: S21, the antenna is rotated to the maintenance position, calibration position, transportation position, and transportation reverse position in steps S11-S14, and the pitch and roll of the array are measured by the theodolite in the corresponding states, which are marked as Dx and Dy; S22, at the four angles of step S21, respectively read the dynamic level meter data on the system status table on the terminal interface, marked as DX and DY; S23, taking the average of the four groups of measurement data and calculating the difference between the average and the dynamic level data to obtain the correction error; S24, record the correction value and compensate it into the back-end processing file.

4. The technology for improving height measurement accuracy based on antenna array calibration according to claim 2 is characterized in that: After step S17, the antenna horizontality data is re-measured according to steps S11-S17, and it is qualified if the error is less than 0.1 degree.

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