CN103837867B - A kind of AIS of utilization information carries out the method for higher-frequency radar antenna channels correction - Google Patents

Abstract

The present invention provides a method for correcting high-frequency radar antenna channels by using AIS information, using a large number of ship AIS information and ship echoes received in the radar coverage sea area, and by analyzing the signal relationship of their responses on different channels, a single Channel Correction for Pole Crossed Loop Antennas. The present invention does not need any artificial auxiliary signal source at all, only needs simple AIS receiving equipment, is a passive and convenient channel correction method, and can be extended to other antenna forms. The advantages of the present invention are: low cost, no need for a large number of complex equipment during active calibration; using a large number of widely distributed ship AIS signals, the channel correction value obtained has good accuracy and stability; the amount of calculation is small, and there is no influence on the shape of the antenna. requirements, a wide range of applications.

Description

A Method of Correcting High Frequency Radar Antenna Channel Using AIS Information

technical field

The invention relates to a method for correcting high-frequency radar antenna channels by using AIS information.

Background technique

High-frequency ground wave radar works in the high-frequency band of 3-30MHz, which can realize over-the-horizon detection of a large range of oceans. It has been widely used to detect sea state parameters, such as current velocity, current direction, and wave height. Since the wavelength of high-frequency signals is comparable to the scale of maneuvering targets (such as aircraft, ships, etc.), a larger scattering cross-section can be obtained, so it also has great potential in detecting hard targets.

High-frequency radars use arrayed or compact antennas to estimate target azimuths through spatial beamforming or direction scanning techniques. The traditional array antenna has the characteristics of high precision and convenient signal processing, but also has the disadvantages of high cost and inconvenient erection. The monopole crossed loop antenna is a compact antenna, which consists of a monopole antenna and two mutually perpendicular electric small loop antennas. It is easy to manufacture, easy to erect and has good performance. Ideally, the horizontal pattern of the monopole antenna is a circle, and the patterns of the two rings are sine and cosine curves respectively. The maximum amplitude responses of the three antennas should be consistent, and the phase responses should be exactly the same.

The principle of monopole cross-loop antenna direction finding is realized by using the target echo in the three channels with different amplitude responses, that is, the "ratio-amplitude" method, which has high requirements on the ideal characteristics of the antenna channel. In actual operation, due to various factors such as the differences in the hardware of each receiving channel and the influence of the surrounding environment, the amplitude and phase characteristics of the three antenna channels are easily changed, far from the ideal antenna characteristics, resulting in antenna channel mismatch . The direct consequence of channel mismatch is to bring significant errors to the direction finding and cause great difficulties to the subsequent processing of radar data. This has become an important factor limiting the popularization and use of monopole cross-loop antennas. In order to ensure the normal operation of the radar, this channel mismatch must be corrected to make the error as small as possible: on the one hand, try to improve the process in hardware production. Ensure that each channel is as consistent as possible; on the other hand, software means can be used to estimate channel mismatch parameters and perform amplitude and phase correction of the receiving channel.

The existing software channel correction methods can be divided into two types: active correction and passive correction. In active calibration, it is necessary to manually set the auxiliary signal source, transmit a reference signal at a sufficient distance from the antenna, and estimate the channel mismatch parameters of the antenna by measuring the amplitude and phase of the output signal of the known signal in each receiving channel. The US CODAR company uses this method to measure the antenna pattern, which requires a lot of extra equipment, is inconvenient to operate, and does not have long-term stability. Chinese patent CN101013147A, the name "high-frequency chirp radar pattern measurement method" provides a method of using a single-frequency continuous sinusoidal signal and utilizing time-frequency analysis to obtain an antenna pattern. Compared with traditional methods, this method greatly reduces the cost of measurement. The cost, but still need an additional signal source, the operation is more inconvenient.

The passive correction method does not require an additional signal source, and directly uses the received echo information together with other prior knowledge to estimate channel mismatch parameters. Compared with active correction, passive correction is a more suitable channel correction method because of its low cost and easy operation. Chinese patent CN1566983A, title "A Method for Array Channel Correction Using Ocean Echo" and Chinese Patent CN1847877A, title "A Passive Channel Correction Method Based on Non-linear Antenna Array" provide two The method of antenna channel correction by echo was applied in the array type high-frequency ground wave radar developed by Wuhan University in the early stage. However, these methods are limited by special array shapes, are not easy to be extended to compact antennas, and the calculation is slightly complicated, and the performance cannot reach the level of active calibration; A method for antenna array channel correction" provides a method for antenna correction using ionospheric echoes, which has a small amount of calculation and good performance, but it is dependent on the ionosphere and lacks sufficient stability; Chinese patent CN102707270A, titled "Automatic Estimation Method of Relative Antenna Pattern of High-frequency Ground Wave Radar" presents a method of calculating antenna pattern through software. This method requires a large amount of calculation, and its practicability needs further verification.

Combining the existing passive correction methods, usually the calculation amount is large and not stable enough, and there is still a lack of widely used and high-performance passive correction methods.

This patent provides a new method for correcting high-frequency radar antenna channels by using AIS information. The automatic identification system (Automatic Idenfication System, AIS) is a new technology developed in the past ten years, which is used for ship traffic management services to identify ships and avoid collisions between ships. This standard was adopted at the General Assembly of the International Maritime Organization in 1998 and has since become a common standard for international ship communications at sea. AIS is based on the principle of self-organizing time division multiple access (SOTDMA) communication. Ships at sea use VHF channels to regularly broadcast their own ship's information to the surrounding area. AIS information is divided into four categories: static information, dynamic information, voyage-related information, and safety-related information. The information mainly utilized in the present invention is the position, speed and time information therein.

Contents of the invention

Aiming at the limitations of existing methods, the purpose of this invention is to provide a method for correcting high-frequency radar antenna channels using AIS information, and to provide a low-cost high-frequency ground wave radar by using the received AIS information and ship echoes. A passive channel correction method that is accurate and applicable to any antenna form.

Technical scheme of the present invention is:

A method for correcting high-frequency radar antenna channels using AIS information, by receiving AIS information from ships carrying AIS transmitters at sea and matching them with target echoes detected by radar, dividing the radar field of view into an angle network with a unit of 1 degree grid, to obtain an average of more than 10 targets per angle grid, and then perform weighted average processing on the matched targets and their amplitudes to correct channel amplitude and phase values; specifically, the following steps are included:

Step 1. On the radar range-Doppler spectrum, a three-level target detection algorithm based on constant false alarm CFAR is used to detect radar target traces;

Step 2, the received AIS data is displayed on the distance-Doppler spectrum correspondingly to the ship carrying the AIS transmitter through the coordinate conversion method from latitude and longitude to polar coordinates;

Step 3. Match the ship carrying the AIS transmitter with the point target detected by the radar on the radar range-Doppler spectrum, read the latitude and longitude of the corresponding ship from the AIS data, and calculate the angle of arrival of the target relative to the radar station ;

Step 4. Count the targets in the same angle grid, accumulate more than 10 targets in each angle grid on average, and weight the echo signal on the two-ring channel to the signal ratio amplitude of the single-pole sub-channel, so as to obtain the Angle channel amplitude correction parameters and phase correction parameters;

Step 5, integrating the entire angle range to obtain the array manifold of the antenna.

The specific implementation process of the step 1 is:

A three-level target detection algorithm based on constant false alarm (CFAR) is used to detect suspected radar target traces on the range Doppler spectrum of radar data obtained in real time, and eliminate targets with signal-to-noise lower than 10dB.

The concrete realization process of described step 2 is:

Use the relatively common simple AIS receiving device on the market to receive the AIS information of ships carrying AIS transmitters at sea, obtain the speed and position information of all ships carrying AIS transmitters in the corresponding time period of the radar field, and eliminate the stationary ships, and the remaining The ship is converted to the radar range-Doppler two-dimensional spectrum through the coordinate transformation method from latitude and longitude to polar coordinates.

The concrete realization process of described step 3 is:

Find the matching combination of the radar target and the AIS target. When the difference between the two is within one distance unit and two Doppler units, the matching is successful, and the matched radar target is used as the correction source.

The concrete realization process of described step 4 is:

Divide the sea area of interest in the radar field of view into M angle grids, put the correction sources with known azimuth angles into the set angle grids, and save the complex response values of each correction source in three channels, namely (X _1ij ,X _2ij ,X _3ij ), where 1, 2, and 3 represent the monopole antenna and the two loops, i represents the angle grid number, and j represents the correction source number that falls into the grid.

The concrete realization process of described step 5 is:

After accumulating more than 10 correction sources for each azimuth on average, perform a weighted average of the amplitude, phase and signal amplitude of all the correction sources in each distance grid to obtain the channel amplitude and phase correction value in this direction. The specific implementation steps include:

For the i-th grid, assuming that there are Ni correction sources, the monopole antenna is used as the reference channel, and the final amplitude correction parameters are:

$\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; kij</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span>}$

The phase correction parameters are:

Among them, i represents the i-th angle grid, k represents the channel number, j represents the correction source serial number of the angle grid, and Ni represents the total number of correction sources of the angle grid;

Combining the correction parameters of each angle grid, the antenna array manifold of the entire radar coverage area is obtained:

Among them, M represents the total number of angle grids.

The innovation of the present invention lies in the first introduction of AIS information into the correction method of the entire array manifold of high-frequency radar, and with the assistance of a large amount of AIS information, the array manifold with high precision can be obtained.

The advantages of the present invention are: there is no need to set additional signal sources, and the cost is low; the algorithm is simple and does not need to use complex iterative optimization algorithms like the previous correction methods; due to the large number of ships in coastal areas and sufficient correction sources, the obtained channel correction parameters Stable and reliable; the correction source comes from a large angle range, so the correction values can be obtained separately for the entire angle range grid, instead of only one set of correction values to correct the ideal antenna characteristics; the correction method has no restrictions on the antenna form, completely Can be ported to other antenna systems.

Description of drawings

Fig. 1 is a working principle diagram of a high-frequency ground wave radar according to an embodiment of the present invention in the prior art.

Fig. 2 is a typical range-Doppler spectrogram of the embodiment of the present invention in the prior art.

Fig. 3 is a pattern diagram of a monopole crossed loop antenna in the prior art.

Fig. 4 is a flowchart of the present invention.

detailed description

Below in conjunction with accompanying drawing, the present invention is described in more detail.

The working principle of high-frequency ground wave radar is shown in Figure 1. High frequency ground wave radar usually consists of a transmitting antenna, a receiving antenna array, a transmitter, a receiver, etc., and the transmitting and receiving are usually co-located. The radar transmitting antenna is a vertical whip antenna whose length is 1/4 of the radar wavelength, and radiates electromagnetic waves outward in all directions. Electromagnetic waves propagate on the sea, and waves, ships, islands, etc. that encounter specific parameters will scatter the electromagnetic waves back and be received by radar receivers. Radar usually adopts a linear frequency modulation system, completes transmission and reception in each frequency sweep cycle, and performs amplification, filtering, frequency mixing, sampling and fast-time discrete Fourier transform after demodulation of the received signal to obtain range spectrum data. The data is uploaded to the PC through the USB bus for subsequent processing. By performing the second discrete Fourier transform on the range spectrum data of N frequency sweep cycles, the separation of velocity information is realized, and the range-Doppler two-dimensional spectrum is obtained, from which the sea state and target information can be extracted. The main strong echoes in the range-Doppler spectrum are sea clutter and target echoes, and sometimes ionospheric echoes and radio frequency interference echoes also exist. The sea clutter is the Bragg scattering caused by ocean waves with a specific wavelength and direction of motion, which is divided into a strong first-order peak and a second-order continuum distributed on both sides of it. Most of the target echoes are distributed between the two first-order peaks. Figure 2 is a typical radar range-Doppler two-dimensional spectrum. The displayed spectrum is from a monopole antenna, and the spectrum of the two rings is similar to it.

The ideal direction diagram of the monopole crossing ring is shown in Figure 3. When a target signal is incident from a certain angle of arrival, the angle can be solved by comparing the signal relationship on the three channels. However, due to the influence of hardware and surrounding environmental factors, the actual pattern of the antenna will deviate from the ideal situation, and corrections must be made. If the relationship between the echoes of the three channels at a certain angle is known in practice, the channel correction value for this angle can be obtained.

The key of the present invention is how to determine the angle information of a large number of target correction sources. The distance and speed of the target on the radar range-Doppler two-dimensional spectrum can be easily calculated, but the incoming wave direction cannot be directly known. However, adding AIS auxiliary information can provide the required angle information.

The schematic flow sheet of the present invention is shown in Fig. 4, and specific implementation steps are as follows:

Step 1. Using a three-level target detection algorithm based on constant false alarm (CFAR), detect suspected radar target spots on the range Doppler spectrum of radar data, and eliminate targets with low signal-to-noise ratios.

Step 2. Use a simple AIS receiving device to receive the AIS information of ships at sea, obtain the speed and position information of all ships in the time period corresponding to the radar field, eliminate the stationary AIS ships, and convert the remaining AIS targets to the radar through the method of coordinate transformation Range-Doppler two-dimensional spectrum.

Step 3. Find the matching combination of the radar target and the AIS target. When the difference between the two is within one distance unit and two Doppler units, the matching is considered successful, and the matched radar target can be used as a correction source.

Step 4. Divide the sea area of interest in the radar field of view into M angle grids, put the correction source of the known azimuth angle into the set angle grid, read and save from the range-Doppler spectrum of the radar The complex response values X _1ij , X _2ij , X _3ij of each calibration source on the three antenna channels, where 1, 2, and 3 represent the monopole antenna and the two loops, i represents the angle grid number, and j represents the The ordinal number of the correction source for the mesh.

Step 5. After accumulating a large number of correction sources in different directions, statistically analyze all the correction sources in each distance grid to obtain the channel amplitude and phase correction values in this direction. The specific method is:

For the i-th grid, assuming that there are N _i correction sources, the monopole antenna is used as the reference channel, and the final amplitude correction parameters are:

$\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; kij</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; |</span>}$

The phase correction parameters are:

Where i represents the i-th angle grid, k represents the channel number, k=1 or 2 or 3, j represents the serial number of the correction source of the angle grid, and Ni represents the total number of correction sources of the angle grid.

Combining the correction parameters of each angle grid, the antenna array manifold of the entire radar coverage area is obtained:

where M represents the total number of angular meshes.

Claims (6)

1. A method utilizing AIS information to carry out high-frequency radar antenna channel correction is characterized in that: by receiving the AIS information of the AIS transmitter ship on the sea and matching with the target echo detected by the radar, the radar field of view is divided into 1 Degree as the unit of the angle grid, to obtain an average of more than 10 targets per angle grid, and then perform weighted average processing on the matched target and its amplitude to correct the channel amplitude and phase value; specifically, the following steps are included: Step 1. On the radar range-Doppler spectrum, a three-level target detection algorithm based on constant false alarm CFAR is used to detect radar target traces; Step 2, the received AIS data is displayed on the distance-Doppler spectrum correspondingly to the ship carrying the AIS transmitter through the coordinate conversion method from latitude and longitude to polar coordinates; Step 3. Match the ship carrying the AIS transmitter with the point target detected by the radar on the radar range-Doppler spectrum, read the latitude and longitude of the corresponding ship from the AIS data, and calculate the angle of arrival of the target relative to the radar station ; Step 4. Count the targets in the same angle grid, accumulate more than 10 targets in each angle grid on average, and weight the echo signal on the two-ring channel to the signal ratio amplitude of the single-pole sub-channel, so as to obtain the Angle channel amplitude correction parameters and phase correction parameters; Step 5, integrating the entire angle range to obtain the array manifold of the antenna. 2. a kind of method utilizing AIS information to carry out high-frequency radar antenna channel correction according to claim 1, is characterized in that: the concrete realization process of described step 1 is: A three-level target detection algorithm based on constant false alarm (CFAR) is used to detect suspected radar target traces on the range Doppler spectrum of radar data obtained in real time, and eliminate targets with signal-to-noise lower than 10dB. 3. a kind of method utilizing AIS information to carry out high-frequency radar antenna channel correction according to claim 2, is characterized in that: the specific realization process of described step 2 is: Use the AIS receiving device to receive the AIS information of ships carrying AIS transmitters at sea, get the speed and position information of all ships carrying AIS transmitters in the corresponding time period of the radar field, remove the stationary ships, and pass the remaining ships through latitude and longitude to pole The coordinate transformation method of the coordinates is converted to the radar range-Doppler two-dimensional spectrum. 4. a kind of method utilizing AIS information to carry out high-frequency radar antenna channel correction according to claim 3, is characterized in that: the concrete realization process of described step 3 is: Find the matching combination of radar target and AIS target, when the difference between the two is one range element, two Doppler Within the unit, that is, the matching is successful, and the matched radar target is used as the correction source. 5. a kind of method utilizing AIS information to carry out high-frequency radar antenna channel correction according to claim 4, is characterized in that: the concrete realization process of described step 4 is: Divide the sea area of interest in the radar field of view into M angle grids, put the correction sources with known azimuth angles into the set angle grids, read and save each correction source on the range-Doppler map The complex response values X _1ij , X _2ij , and X _3ij in the three channels, where 1, 2, and 3 represent channel numbers, i represents the number of the angle grid, and j represents the number of the calibration source falling into the grid. 6. a kind of method utilizing AIS information to carry out high-frequency radar antenna channel correction according to claim 5, is characterized in that: the concrete realization process of described step 5 is: After accumulating more than 10 correction sources for each angle grid on average, perform a weighted average of the amplitude, phase and signal amplitude of all the correction sources in each angle grid to obtain the channel amplitude correction parameters and phase correction parameters of the angle grid; The specific implementation steps include: For the i-th grid, assuming that there are Ni correction sources, the monopole antenna is used as the reference channel, and the final amplitude correction parameters are: $\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span>}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span>}$ The phase correction parameters are: Among them, i represents the number of the angle grid, k represents the channel number, j represents the number of the correction source falling into the grid, and Ni represents the total number of correction sources of the angle grid; Combining the correction parameters of each angle grid, the antenna array manifold of the entire radar coverage area is obtained: Among them, M represents the total number of angle grids.