A beam scanning method for conical radar

Abstract

The present invention belongs to the technical field of phased array radar, and specifically relates to a beam scanning method of a conical radar, wherein the radar beam scans in the azimuth dimension and the pitch dimension; in the azimuth dimension, the radar has a total of 4N TRs, and the formation of each azimuth beam requires N TRs, N being greater than or equal to 12, so as to achieve simultaneous retention of 4 beams; according to the azimuth dimension, the beam width is divided into a wide beam emission and a narrow beam emission, the wide beam is used for target search, recorded as a search beam, and the narrow beam is used for target tracking, recorded as a tracking beam, and the azimuth beam achieves 360° all-round scanning; in the pitch dimension, each TR of the radar contains M array elements, M being greater than or equal to 6, and is divided into 4 search beams, recorded as L, M1, M2, and H, according to the pitch center pointing of the search beam, and the tracking beam achieves beam retention at any pitch angle of ‑5 to +55 degrees. The present invention can simultaneously perform multi-beam and multi-angle search and tracking; and has a higher elevation detection capability.

Description

Technical Field

[0001] The invention belongs to the technical field of phased array radars, and in particular relates to a beam scanning method of a conical radar. Background Art

[0002] With the gradual opening of the country's low-altitude aviation field, the application of DMX equipment is rapidly becoming popular. At the same time, the problem of illegal flying of DMX equipment has gradually begun to threaten the safety of the public. The use of radar technology to effectively detect DMX targets is of great significance in defending DMX equipment.

[0003] At present, the phased array or the combination of the array and the servo is usually used to detect DMX targets such as drones. It is difficult to achieve a rapid response to 360-degree all-round warnings during the detection process. Therefore, it is necessary to invent a low-altitude detection radar with all-round and rapid response. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a beam scanning method for a conical radar.

[0005] The specific technical solutions are:

[0006] A beam scanning method for a conical radar, wherein the beam can be scanned in an azimuth dimension and an elevation dimension.

[0007] In the azimuth dimension, the radar has a total of 4N TRs. The formation of each azimuth beam requires N (greater than or equal to 12) TRs, and 4 beams can be stationed at the same time. According to the azimuth dimension, the beam width can be divided into transmitting wide beams and transmitting narrow beams. The wide beam is used for target search and is recorded as the search beam. The narrow beam is used for target tracking and is recorded as the tracking beam. The azimuth beam realizes 360° full-range scanning.

[0008] In the pitch dimension, each TR of the radar contains M (greater than or equal to 6) array elements, which are divided into four search beams according to the pitch center direction of the search beam, denoted as L, M1, M2, and H. The tracking beam can achieve beam retention at any pitch angle between -5 and +55 degrees.

[0009] Furthermore, each array element on the radar TR of the present invention contains a phase shifter, and a beam is formed by changing the TR used and the phase shifter matching value. When selecting the TR used, the beam pointing azimuth angle is ensured to be the center, and N / 2 TRs are used on the left and right. The wide beam phase control value is formed by the beam widening algorithm and solidified in the program, and the narrow beam is calculated in real time according to the required pointing angle, and the calculation formula is.

[0010]

[0011] Where m is the column number and n is the row number. It can be expressed as:

[0012]

[0013] Among them, is the azimuth and elevation angle to be pointed.

[0014] is the radius of the nth row, which can be expressed as:

[0015]

[0016] Where is the radius of the bottom antenna, is the array spacing, which is determined by the actual array antenna installed, is the semi-cone angle of the array antenna,

[0017] is the array element azimuth, which can be expressed as:

[0018]

[0019] Furthermore, 5 receiving beams are used when transmitting a wide beam, and 2 receiving beams are used when transmitting a narrow beam, and digital beams with different pointing angles are formed by changing the DBF value. The radar contains one or more signal acquisition and preprocessing boards to realize ADC, DDC and DBF processing of analog signals, and DBF data is transmitted to the server via high-speed optical fiber for subsequent radar signal processing.

[0020] Furthermore, the search and tracking beam dwell times can be flexibly modified according to the electromagnetic environment in which the radar is used, allowing the search and tracking cycles to be flexibly adjusted while meeting the target detection capability.

[0021] Furthermore, the search beam and the tracking beam are switched according to the beam scheduling algorithm. When the radar detects a target, it is divided into three working modes: TWS, TAS, and CTT. In TWS mode, the radar uses a wide beam to search for targets. In CTT mode, the radar uses a tracking mode to track targets. In TAS mode, the radar searches for targets and tracks targets, and inserts several search frames after tracking all targets. The three modes of TWS, TAS, and CTT can be switched alternately.

[0022] In TWS mode, the radar performs search tasks according to the wave position number;

[0023] In CTT mode, the rule for determining the tracking times of all targets is:

[0024] When the number of targets is 1, set the tracking times to 1;

[0025] When there are two targets, calculate the azimuth angle difference between the targets. If it is greater than or equal to 90°, set the tracking number to 1 (two targets are tracked simultaneously using different beams). If it is less than 90°, set the tracking number to 2 (two targets need to be tracked using different beams in different time periods).

[0026] When the number of targets is 3, calculate the azimuth angle difference between any two targets. If both are greater than or equal to 90°, set the tracking number to 1 (three targets are tracked using different beams at the same time). If both differences are greater than or equal to 90°, set the tracking number to 2 (two targets are tracked using different beams at the same time, and one target needs to be tracked using different beams in different time periods). If both differences are less than 90°, set the tracking number to 3 (three targets need to be tracked using different beams in different time periods).

[0027] When the number of targets is 4, calculate the azimuth angle difference between any two targets. When all are greater than or equal to 90°, set the tracking number to 1 (4 targets are tracked using unused beams at the same time); when 3 are greater than or equal to 90°, set the tracking number to 2 (3 targets are tracked using unused beams at the same time, and 1 target needs to be tracked using unused beams in a time-sharing manner); when 2 are greater than or equal to 90°, set the tracking number to 3 (2 targets are tracked using unused beams at the same time, and 2 targets need to be tracked using unused beams in a time-sharing manner); when all are less than 90°, set the tracking number to 4 (4 targets need to be tracked using unused beams in a time-sharing manner).

[0028] The overall process of the radar's TAS mode is similar to that of the CTT mode, but the tracking cycle is longer than the actual tracking time, and several frame scans are performed after the tracking is completed. After receiving the tracking instruction (including the list of tracking targets, the accumulated points of each target, and the set tracking cycle), the main control board schedules and allocates the beam. The main control board determines the targets to be tracked simultaneously based on the pitch angle, azimuth, and accumulated points of each target, arranges the tracking of each target into several tracking frames, and calculates the time required to complete the tracking of all targets. At this time, the set tracking cycle should be greater than the next tracking time. The scanning time is obtained by subtracting the actual tracking time from the set tracking cycle, and the scanning frames are arranged in the scanning time to calculate the next tracking time (to ensure that the actual TAS time is less than or equal to the tracking cycle at the end of the last scanning frame). After obtaining the next tracking time, send it to the display and control software.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] It can conduct multi-beam, multi-angle search and tracking simultaneously;

[0031] The antenna array is conical in shape, which allows for higher elevation angle detection capabilities while retaining the ability to detect ground targets;

[0032] The search waveforms and beam dwell times are different at different elevation angles, and the dwell time can be flexibly adjusted to adapt to different usage environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the installation of the conical array radar array of the present invention;

[0034] Figure 2 It is a schematic diagram of four-beam simultaneous scanning of the present invention;

[0035] Figure 3 It is a schematic diagram of a wide beam in the pitch dimension of the present invention;

[0036] Figure 4 This is a schematic diagram of TR numbering and acquisition board numbering of the present invention;

[0037] Figure 5 The beamforming flow chart of the present invention;

[0038] Figure 6 The radar mode switching flow chart of the present invention;

[0039] Figure 7 This is the tracking number calculation process of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Conical array radar antenna installation diagram Figure 1 As shown, it is assumed that a conical array radar consists of 48 TRs, each TR contains 6 array elements.

[0042] like Figure 2 As shown, the azimuth width of the transmitted wide beam is 30°, and during the four-wave position search, 4*30=120° azimuth dimension detection can be performed per CPI.

[0043] like Figure 3 As shown, a schematic diagram of the four search beam positions in the pitch dimensions L, M1, M2, and H; the four beams are switched sequentially when searching for targets.

[0044] In this embodiment, the radar N=12, M=48, the column number m ranges from 0 to 47, the row number ranges from 0 to 5, and the azimuth angle corresponding to each TR is as follows: Figure 4 shown.

[0045] like Figure 5As shown in the beamforming flow chart, when performing a search task, first calculate the 12 consecutive TRs that need to be used. The TRs used are determined according to the search beam center angle to ensure that 6 TRs are used on the left and right. After all TRs are confirmed, the phase shifters of the TRs used can be matched to change the direction of the transmit beam. The matching angle is calculated according to the beam widening algorithm, which is solidified in the program and the corresponding angle can be directly issued.

[0046] When performing the tracking task, the TR used is the same as the search task, and the phase shifter phase value is calculated according to the following formula:

[0047]

[0048] Where m is the column number and n is the row number. mn (It can be expressed as:

[0049]

[0050] Where θ is the azimuth and elevation angle to be pointed.

[0051] is the radius of the nth row, which can be expressed as:

[0052] r n =r b -nΔdsinφ0

[0053] Where is the radius of the bottom antenna, is the array spacing, which is determined by the actual array antenna installed, is the semi-cone angle of the array antenna,

[0054] is the array element azimuth, which can be expressed as:

[0055]

[0056] After determining the TR used and the array element phase value of TR, the required digital DBF coefficient is calculated. In this embodiment, 5 receiving beams are used in the search frame, numbered 0 to 4. The pitch dimensions of the 5 receiving beams are the same as the direction of the transmitting beam, and the receiving beam width in the azimuth dimension is recorded as θ B , the five receiving beams are pointed to -2θ in sequence B , -θ B , 0, θ B , 2θ B ,

[0057] In this embodiment, two receiving beams are used in the tracking frame, numbered 0 to 1, and the elevation dimensions of the two receiving beams are the same as the direction of the transmitting beam. The two receiving beams are sequentially pointed to -0.5θ B , 0.5θ B .

[0058] In this embodiment, the number of PRTs is configured by the host computer and can be adjusted at any time according to the electromagnetic environment of the radar station.

[0059] TWS, CTT, TAS Figure 6 The process shown in the figure is switched. When the radar is working, the upper computer first issues a monitoring command, and the lower computer enters the TWS mode to search for the target. After the target is found, the upper computer switches between modes according to the target threat level. When there is no threat, the TWS mode is maintained, when there is a medium threat, the TAS mode is entered, and when there is a high threat, the CTT mode is directly entered. The number of target tracking times in CTT mode is calculated by Figure 7 The calculation process is shown.

Claims

1. A beam scanning method for a conical radar, characterized in that: The radar beam scans in the azimuth and elevation dimensions; In the azimuth dimension, the radar has a total of 4N TRs. Each azimuth beam requires N TRs, where N is greater than or equal to 12, to achieve simultaneous stationary 4 beams. The beam width in the azimuth dimension is divided into a wide beam and a narrow beam. The wide beam is used for target search and is recorded as a search beam. The narrow beam is used for target tracking and is recorded as a tracking beam. The azimuth beam achieves 360° all-round scanning. In the elevation dimension, each TR of the radar contains M array elements, M is greater than or equal to 6. According to the elevation center direction of the search beam, it is divided into 4 search beams, denoted as L, M1, M2, and H. The tracking beam can achieve beam dwell at any elevation angle from -5 to +55 degrees. The search beam and tracking beam are switched according to the beam scheduling algorithm. When the radar detects a target, it is divided into three working modes: TWS, TAS, and CTT. In TWS mode, the radar uses a wide beam to search for targets. In CTT mode, the radar uses a tracking mode to track targets. In TAS mode, the radar searches for targets and tracks targets. After tracking all targets, several search frames are inserted. The three modes of TWS, TAS, and CTT are switched alternately. In TWS mode, the radar performs search tasks according to the wave position number; In CTT mode, the rule for determining the tracking times of all targets is: When the number of targets is 1, set the tracking times to 1; When there are two targets, the azimuth angle difference between the targets is calculated. When it is greater than or equal to 90°, the tracking number is set to 1, and the two targets are tracked simultaneously using different beams; when it is less than 90°, the tracking number is set to 2, and the two targets need to be tracked using different beams in different time periods. When there are 3 targets, calculate the azimuth angle difference between any two targets. If both are greater than or equal to 90°, set the tracking number to 1, and all three targets will be tracked using different beams at the same time. When both differences are greater than or equal to 90°, set the tracking number to 2, and both targets will be tracked using different beams at the same time, and one target will need to be tracked using different beams in different time periods. When both differences are less than 90°, set the tracking number to 3, and all three targets will need to be tracked using different beams in different time periods. When there are 4 targets, calculate the azimuth angle difference between any two targets. If all of them are greater than or equal to 90°, set the tracking number to 1, and all 4 targets will be tracked using unused beams at the same time; if all of them are greater than or equal to 90°, set the tracking number to 2, and all 3 targets will be tracked using unused beams at the same time, and 1 target will need to be tracked using unused beams in a time-sharing manner; if all of them are greater than or equal to 90°, set the tracking number to 3, and all 2 targets will be tracked using unused beams at the same time, and all 2 targets will need to be tracked using unused beams in a time-sharing manner; if all of them are less than 90°, set the tracking number to 4, and all 4 targets will need to be tracked using unused beams in a time-sharing manner; The overall process of the radar's TAS mode is the same as that of the CTT mode, but the tracking cycle is longer than the actual tracking time, and several frame scans are performed after the tracking is completed; after receiving the tracking command, the main control board schedules and allocates the beam; The main control board determines the targets to be tracked simultaneously according to the pitch angle, azimuth angle and accumulated points of each target, arranges the tracking of each target into several tracking frames, and calculates the time required to complete the tracking of all targets; at this time, the tracking cycle should be set to be greater than the next tracking time; the scanning time is obtained by subtracting the actual tracking time from the set tracking cycle, and the scanning frames are arranged in the scanning time to calculate the next tracking time; After getting the next tracking time, send it to the display and control software.

2. The beam scanning method of a conical radar according to claim 1, characterized in that: Each array element on the TR contains a phase shifter. The beam is formed by changing the TR used and the phase shifter matching value. When selecting the TR to be used, ensure that the beam pointing azimuth is the center, and use N / 2 TRs on the left and right. The wide beam phase control value is formed by the beam widening algorithm and solidified in the program. The narrow beam is calculated in real time according to the required pointing angle. The calculation formula is: Where m is the column number, n is the row number; the path difference of each array element is It is expressed as: Among them, is the azimuth and elevation angle to be pointed; r n is the radius of the nth row, expressed as: r n =r b -nΔd sinφ0 where r b is the radius of the bottom antenna, Δd is the array spacing, which is determined by the actual array antenna installed, and φ0 is the semi-cone angle of the array antenna; θ m is the array element azimuth, expressed as:

3. The beam scanning method of a conical radar according to claim 1, characterized in that: The receiving beam is a digital multi-beam. Five receiving beams are used when transmitting a wide beam, and two receiving beams are used when transmitting a narrow beam. Digital beams with different pointing angles are formed by changing the DBF value. The radar contains one or more signal acquisition and preprocessing boards to realize ADC, DDC and DBF processing of analog signals. The DBF data is transmitted to the server via high-speed optical fiber for subsequent radar signal processing.

4. The beam scanning method of a conical radar according to claim 1, characterized in that: The dwell time of search and tracking beams at different elevation angles can be flexibly modified according to the electromagnetic environment in which the radar is used. The search and tracking cycle can be flexibly adjusted while meeting the target detection capability. The dwell time is achieved by changing the number of PRTs per frame.

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