Radar target accurate tracking method based on pointing control bias

Abstract

The invention relates to a pointing control bias radar target accurate tracking method, and belongs to the technical field of tracking radars. The method comprises the steps of forming an angle measurement signal and forming a pointing control offset. The angle measurement signal forming step comprises the following steps: carrying out four-quadrant subarray division on an antenna plane, and respectively carrying out receiving, AD sampling, DDC and sum and difference signal forming. The pointing offset forming step comprises the steps of dividing an area within the beam width into a low signal-to-noise ratio area and a high signal-to-noise ratio area, and selecting the pointing offset according to the area division position. Accurate tracking is realized by adjusting, aligning and pointing bias in tracking angle measurement, and the method is a process integrating closed-loop control and measurement and has the advantages of high iteration speed and high convergence precision. According to the method, the problems that the angle measurement precision of the tracking radar becomes poor under the existing low signal-to-noise ratio condition, and even the angle measurement numerical value periodically turns over and jumps around the true value are solved.

Description

Technical Field

[0001] The invention relates to the technical field of tracking radars, and in particular to a radar target precise tracking method based on pointing control bias. Background Art

[0002] Tracking radar is a radar that can continuously track a target and measure the target's coordinates. Tracking radar can be used to obtain accurate measurement parameters of the target's continuous motion trajectory. Based on the coordinate measurement results of the tracked target, the antenna beam of the tracking radar can always point to the target, thus providing continuous target coordinate measurement information. Angle measurement accuracy performance is an important indicator of tracking radar, and it is also an important factor that affects the construction of more advanced systems.

[0003] The two-dimensional sum and difference angle measurement method is commonly used for target angle measurement. The general practice is to divide the antenna array into four beams, and use these four beams to form the sum channel, azimuth difference channel, and elevation difference channel. The signals of these channels are observed and calculated to obtain the deviation angle of the target from the center of the beam. This method has high calculation accuracy and small amount of calculation, and is widely used in engineering. However, due to the limitation of signal-to-noise ratio, especially as the target gets closer and closer to the center of the radar antenna, the signal strength of the difference channel becomes smaller and smaller, and the signal-to-noise ratio on which the angle measurement depends becomes worse and worse, which not only affects the target angle measurement accuracy, but also causes the radar antenna to be unable to accurately point to the target under low signal-to-noise ratio conditions, and even causes the angle measurement value to periodically flip and jump around the true value. Summary of the invention

[0004] The technical problems to be solved by the present invention are:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides a radar target precise tracking method based on pointing control bias, so as to solve the problem that the angle measurement accuracy of the existing tracking radar under low signal-to-noise ratio conditions deteriorates, and even causes the angle measurement value to periodically flip and jump around the true value.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A radar target accurate tracking method based on pointing control bias, characterized by comprising:

[0008] Acquire the sum channel, pitch difference channel, and azimuth difference channel signals;

[0009] The ratio of the pitch difference channel to the sum channel is calculated based on the sum channel and the pitch difference channel; the pitch angle measurement value of the target deviating from the beam center is calculated based on the ratio of the pitch difference channel to the sum channel; the pitch angle measurement value of the target in the radar antenna coordinate system is calculated based on the pitch angle measurement value of the target deviating from the beam center;

[0010] Based on the sum channel and the azimuth difference channel, the ratio of the azimuth difference channel to the sum channel is calculated; based on the ratio of the azimuth difference channel to the sum channel, the azimuth angle measurement value of the target deviating from the beam center is calculated; based on the azimuth angle measurement value of the target deviating from the beam center, the azimuth angle measurement value of the target in the radar antenna coordinate system is calculated;

[0011] The pointing offset is performed according to the pitch angle measurement value and azimuth angle measurement value of the target in the radar antenna coordinate system, and the offset amount is selected as 0.2 beam width; the control pointing position is:

[0012]

[0013] Among them, ele is the pitch control direction, is the measured elevation angle of the target in the radar antenna coordinate system, θ ele_3dB is the 3dB elevation beam width, azi is the azimuth control pointing position, θ azi_3dB is the azimuth measurement value of the target in the radar antenna coordinate system, is the 3dB azimuth beamwidth.

[0014] A further technical solution of the present invention is to perform a pointing bias according to the pitch angle measurement value and the azimuth angle measurement value of the target in the radar antenna coordinate system, through 2-3 iterations.

[0015] A further technical solution of the present invention: the acquisition of the sum channel, the pitch difference channel, and the azimuth difference channel signals comprises:

[0016] The antenna plane is divided into four quadrants, namely: sub-array 1, sub-array 2, sub-array 3, and sub-array 4;

[0017] The RF signal outputted from the antenna plane is received and converted into corresponding 4-channel intermediate frequency signals after passing through the receiver;

[0018] The 4-channel intermediate frequency signals are sampled by AD sampling to obtain the corresponding 4-channel digital intermediate frequency signals;

[0019] The 4-channel digital intermediate frequency signals are digitally down-converted by digital down-conversion to output corresponding 4-channel digital baseband signals;

[0020] Perform sum and difference operations on these four digital baseband signals to obtain sum channel, elevation difference channel, and azimuth difference channel signals.

[0021] A further technical solution of the present invention is as follows: the pitch angle measurement value of the target deviating from the beam center is calculated based on the ratio of the pitch difference channel to the sum channel, using the following formula:

[0022]

[0023] Among them, F is the functional relationship, It is the ratio of the pitch difference channel to the sum channel.

[0024] A further technical solution of the present invention is as follows: the pitch angle measurement value of the target in the radar antenna coordinate system is calculated based on the pitch angle measurement value of the target deviating from the beam center, using the following formula:

[0025]

[0026] in, It is the measured value of the target's elevation angle in the radar antenna coordinate system.

[0027] A further technical solution of the present invention is as follows: the azimuth angle measurement value of the target deviating from the beam center is calculated based on the ratio of the azimuth difference channel to the sum channel, using the following formula:

[0028]

[0029] Among them, G is the functional relationship, is the ratio of the azimuth difference channel to the sum channel.

[0030] A further technical solution of the present invention is as follows: the azimuth angle measurement value of the target in the radar antenna coordinate system is calculated based on the azimuth angle measurement value of the target deviating from the beam center, using the following formula:

[0031]

[0032] in, It is the azimuth measurement value of the target in the radar antenna coordinate system.

[0033] A computer system, characterized in that it comprises: one or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method.

[0034] A computer-readable storage medium, characterized in that it stores computer-executable instructions, which are used to implement the above method when executed.

[0035] A computer program product, characterized by comprising computer executable instructions, wherein the instructions are used to implement the above method when executed.

[0036] The beneficial effects of the present invention are:

[0037] The radar target precise tracking method based on pointing control bias provided by the present invention has the following advantages compared with the prior art:

[0038] 1. The angle measurement signal formation process uses common radar sub-array division, which is easy to implement;

[0039] 2. The pointing control bias enables the radar antenna to stably provide angle measurement values ​​with a high signal-to-noise ratio, thus ensuring the accuracy of angle measurement;

[0040] 3. The selected fitting straight line intersects with the theoretical curve at the offset position, which greatly reduces the amount of calculation and storage while ensuring accurate angle measurement;

[0041] 4. The tracking angle measurement of the present invention achieves accurate tracking by adjusting the alignment pointing bias. It is a process that combines closed-loop control and measurement, and has the advantages of fast iteration speed and high convergence accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0043] Figure 1 Schematic diagram of the automatic test method and equipment composition for phase balancing of phased array antennas of the present invention

[0044] Figure 2 This is the offset interval division of the target tracking angle of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] The invention provides a radar target precise tracking method based on pointing control bias, and the implementation contents involved include: forming an angle measurement signal and forming a pointing control bias.

[0048] The step of forming the angle measurement signal includes dividing the antenna plane into four quadrant sub-arrays, and performing reception, AD sampling, DDC (digital down conversion), and forming sum and difference signals respectively. The step of forming the pointing bias includes dividing the area within the beam width into a low signal-to-noise ratio area and a high signal-to-noise ratio area, and selecting the pointing bias according to the area division position.

[0049] Preferably, the system controls to perform multiple angle measurements according to the angle measurement results, and after 2 to 3 iterations, it can stably converge on the pointing bias position to ensure the signal-to-noise ratio of the angle measurement.

[0050] Preferably, in order to reduce the amount of calculation, the present invention can reduce the amount of calculation while ensuring the angle measurement accuracy by selecting the fitting straight line to intersect the theoretical curve at the position of the pointing offset.

[0051] In order to enable those skilled in the art to better understand the present invention, the present invention is described in detail below in conjunction with specific embodiments.

[0052] refer to Figure 1 As shown, this embodiment provides a method for obtaining an input signal for angle measurement, and the equipment involved in the method includes: an antenna plane 10, a receiver 20, an AD sampling 30, a digital down-conversion 40, and a channel 50, a pitch difference channel 60, and an azimuth difference channel 70.

[0053] refer to Figure 2 As shown, the tracking convergence point selection involved in the method includes: a theoretical angle measurement curve 80, a selected angle measurement straight line 90, a low signal-to-noise ratio area 100, and a high signal-to-noise ratio area 110.

[0054] The radar target precise tracking method based on pointing control bias provided in this embodiment needs to divide the antenna plane 10 into four quadrants during implementation, namely: subarray 1, subarray 2, subarray 3, and subarray 4; the RF signal corresponding to the output of the antenna plane 10 is received, and converted into corresponding four intermediate frequency signals after passing through the receiver 20; the four intermediate frequency signals are subjected to intermediate frequency sampling by AD sampling 30 to obtain corresponding four digital intermediate frequency signals; the four digital intermediate frequency signals are subjected to digital down conversion by digital down conversion 40 to output corresponding four digital baseband signals; and the four digital baseband signals are subjected to sum and difference operations to obtain a sum channel 50, a pitch difference channel 60, and an azimuth difference channel 70.

[0055] Among them, the sum channel 50 corresponds to the sum of the four channels, marked as S(1+2+3+4) or S all , that is, the complex digital signals of each channel output by the digital down-converter 40 are subjected to the following operation: S1+S2+S3+S4; the pitch difference 60 corresponds to the difference between the synthesis of the upper two sub-arrays and the synthesis of the lower two sub-arrays, which is marked as S(1+2-3-4) or S ele, that is, the complex digital signals of each channel output by the digital down-converter 40 are subjected to the following operation: S1+S2-S3-S4; the azimuth difference 70 corresponds to the difference between the synthesis of the two left sub-arrays and the synthesis of the two right sub-arrays, which is marked as S(1-2-3+4) or S azi , that is, the complex digital signals of each channel output by the digital down-converter 40 are subjected to the following operation: S1-S2-S3+S4.

[0056] The deviation angle of the target from the beam center is related to S all , S ele , S azi There is a function mapping relationship, which will form a theoretical angle measurement curve 80. If the mechanical scanning method of the traditional antenna is used, the curve only corresponds to the deviation angle (Δ ele , Δ azi ) is related; if the electronic scanning method of the two-dimensional phased array antenna is adopted, if the curve has the deviation angle (Δ ele , Δ azi ), it is also related to the beam pointing (ele, azi). Here we consider the more complex electronic scanning method of two-dimensional phased array antenna.

[0057] The ratio of the pitch difference channel to the sum channel is expressed as R ele Indicates. Figure 1 The measured values ​​obtained by implementation are:

[0058]

[0059] The theoretical value is

[0060] R ele =F(Δ ele ,ele,azi)

[0061] Among them, F is the functional relationship.

[0062] In the above, ele,azi are known wave position control quantities, so Δ ele With R ele It is a one-to-one mapping relationship.

[0063] That is, we can use the inverse function to find out, Δ ele =F -1 (R ele ) ele,azi .

[0064] Corresponding to Figure 1 The measured value implemented can obtain the target's elevation angle measurement value from the center of the antenna beam as

[0065]

[0066] According to the above results, the measured pitch angle of the target in the radar antenna coordinate system can be calculated as follows:

[0067]

[0068] Similarly, the azimuth angle measurement value of the target in the radar antenna coordinate system can be obtained as:

[0069] in

[0070] in, is the azimuth angle measurement value of the target deviating from the center of the antenna beam, and G is the functional relationship.

[0071] refer to Figure 2 As shown, in order to solve the problem that the angle measurement accuracy of the existing tracking radar under low signal-to-noise ratio conditions deteriorates and may even cause the angle measurement value to periodically flip and jump around the true value, it is divided into a low signal-to-noise ratio area 100 and a high signal-to-noise ratio area 110 according to the degree of deviation of the target from the center of the beam.

[0072] When selecting, the region [-0.2, +0.2] of the normalized beam width away from the beam center is a low signal-to-noise ratio region 100; the region [-0.2, -0.5] and (+0.2, -0.5] of the normalized beam width away from the beam center is a high signal-to-noise ratio region 110.

[0073] When the target appears in the low SNR area 100, the target is facing the beam center. Although the SNR of the sum channel signal is the best, the SNR of the difference channel signal is the worst. When the SNR of the sum channel is weak, the difference channel signal will be submerged in the system noise and cannot be detected. Make accurate calculations.

[0074] When the target appears in the high signal-to-noise ratio area 110, the target deviates from the beam center. At this time, the signal-to-noise ratio of the difference channel signal is greatly improved in exchange for the attenuation of the sum channel signal by no more than 3dB. Accurate calculations are possible.

[0075] A key point of the present invention is that according to the target angle measurement value The pointing bias is selected to be 0.2 beam width. That is, the system controls the measured value Based on this, the beam is accurately controlled to point to a position that deviates from the center of the beam. The control direction is

[0076]

[0077] Among them, θ ele_3dB represents the 3dB elevation beam width, θ azi_3dB Indicates the 3dB azimuth beamwidth.

[0078] Under the pointing control bias condition, the system control can generally converge the beam pointing to a position with a bias of 0.2 beam width through 2 iterations of pointing. For some worse random situations, when the target randomly appears in the low signal-to-noise ratio area 100 once, the beam pointing can quickly leave the low signal-to-noise ratio area 100 due to the pointing bias of the system control, and thus converge into the high signal-to-noise ratio area 110. At this time, the cumulative number of system control iterations does not exceed 3.

[0079] Preferably, in order to reduce the amount of calculation and storage in implementation, a straight line 90 with a slope of k can be used to fit the theoretical angle measurement curve 80. Another key point of the present invention is that the selected fitting angle measurement straight line 90 should be able to overlap with the theoretical angle measurement curve 80 within 0.2 beam width. The significant benefit of this is that even if the selected angle measurement straight line 90 has different degrees of deviation from the theoretical angle measurement curve 80, since the curve is monotonic, the results of multiple iterations will still fall within the designed 0.2 beam width.

[0080] The angle measurement result of the converged position is designed as above, so there is no obvious deviation from the theoretical angle measurement true value, thus ensuring the accuracy of radar tracking angle measurement.

[0081] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A radar target accurate tracking method based on pointing control bias, characterized in that: include: Acquire the sum channel, pitch difference channel, and azimuth difference channel signals; The ratio of the pitch difference channel to the sum channel is calculated based on the sum channel and the pitch difference channel, and the pitch angle measurement value of the target deviating from the beam center is calculated based on the ratio of the pitch difference channel to the sum channel; Calculate the target's elevation angle measurement value in the radar antenna coordinate system based on the target's elevation angle measurement value that deviates from the beam center; The ratio of the azimuth difference channel to the sum channel is calculated based on the sum channel and the azimuth difference channel, and the azimuth angle measurement value of the target deviating from the beam center is calculated based on the ratio of the azimuth difference channel to the sum channel; Calculate the azimuth angle measurement value of the target in the radar antenna coordinate system based on the azimuth angle measurement value of the target deviating from the beam center; The pointing offset is performed according to the pitch angle measurement value and azimuth angle measurement value of the target in the radar antenna coordinate system, and the offset amount is selected as 0.2 beam width; the control pointing position is: Among them, ele is the pitch control direction, is the measured elevation angle of the target in the radar antenna coordinate system, θ ele_3dB is the 3dB elevation beam width, azi is the azimuth control pointing position, θ azi_3dB is the azimuth measurement value of the target in the radar antenna coordinate system, is the 3dB azimuth beamwidth.

2. The radar target precise tracking method based on pointing control bias according to claim 1, characterized in that: The pointing bias is performed based on the target’s elevation angle measurement value and azimuth angle measurement value in the radar antenna coordinate system, through 2-3 iterations.

3. The radar target precise tracking method based on pointing control bias according to claim 1, characterized in that: The obtaining of the sum channel, the pitch difference channel, and the azimuth difference channel signals includes: The antenna plane is divided into four quadrants, namely: sub-array 1, sub-array 2, sub-array 3, and sub-array 4; The RF signal outputted from the antenna plane is received and converted into corresponding 4-channel intermediate frequency signals after passing through the receiver; The 4-channel intermediate frequency signals are sampled by AD sampling to obtain the corresponding 4-channel digital intermediate frequency signals; The 4-channel digital intermediate frequency signals are digitally down-converted by digital down-conversion to output corresponding 4-channel digital baseband signals; Perform sum and difference operations on these four digital baseband signals to obtain sum channel, elevation difference channel, and azimuth difference channel signals.

4. The radar target precise tracking method based on pointing control bias according to claim 1, characterized in that: The pitch angle measurement value of the target deviating from the beam center is calculated based on the ratio of the pitch difference channel to the sum channel, using the following formula: Among them, F is the functional relationship, It is the ratio of the pitch difference channel to the sum channel.

5. The radar target precise tracking method based on pointing control bias according to claim 4 is characterized in that: The pitch angle measurement value of the target in the radar antenna coordinate system is calculated based on the pitch angle measurement value of the target deviating from the beam center, using the following formula: in, It is the measured value of the target's elevation angle in the radar antenna coordinate system.

6. The radar target precise tracking method based on pointing control bias according to claim 1, characterized in that: The azimuth angle measurement value of the target deviating from the beam center is calculated based on the ratio of the azimuth difference channel to the sum channel, using the following formula: Among them, G is the functional relationship, is the ratio of the azimuth difference channel to the sum channel.

7. The radar target precise tracking method based on pointing control bias according to claim 6 is characterized in that: The azimuth angle measurement value of the target in the radar antenna coordinate system is calculated based on the azimuth angle measurement value of the target deviating from the beam center, using the following formula: in, It is the azimuth measurement value of the target in the radar antenna coordinate system.

8. A computer system, characterized in that include: One or more processors, and a computer-readable storage medium for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors are enabled to implement the method of claim 1.

9. A computer-readable storage medium, characterized in that Computer executable instructions are stored, and when the instructions are executed, they are used to implement the method of claim 1.

10. A computer program product, characterized in that The invention comprises computer executable instructions, which are used to implement the method of claim 1 when being executed.

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