Method for measuring target direction of arrival of array radar

Abstract

The invention discloses a target direction of arrival measurement method of an array radar, which relates to the technical field of direction measurement and comprises the steps of configuring IP address information of a remote control area server of the array radar, entering an environment early warning end, monitoring environment parameters in real time and detecting whether array errors occur in electromagnetic characteristics of array elements in an antenna array or not. The method comprises the following steps: detecting whether an antenna array is abnormal, identifying when the antenna array is abnormal, sending out an early warning prompt in real time, entering an independent distribution end, monitoring snapshot data in a short-time burst signal environment in real time, carrying out independent identical distribution classification, realizing independent distribution of the antenna array, entering a multi-path adjustment end, and detecting whether a scatterer exists around the array antenna in real time. According to the target direction-of-arrival measurement method of the array radar, the condition of array errors caused by inconsistency of electromagnetic characteristics of array elements in an antenna array due to factors such as environment temperature and humidity is avoided, large error or rank loss of estimation of a covariance matrix is avoided, and shielding or blurring of a measurement direction and a sight line is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of direction measurement, and in particular to a method for measuring the target arrival direction of an array radar. Background Art

[0002] Array radar is a radar system that uses an array composed of multiple antenna units to transmit and receive electromagnetic waves. It forms a scanning beam by controlling the signal phase on these units. Array radar uses advanced antenna arrays and digital technology to achieve efficient and flexible electromagnetic wave scanning and multi-target tracking capabilities. Different types of array radars each have unique advantages and application scenarios, and play an important role from strategic early warning to meteorological monitoring.

[0003] At present, with the increasing popularity of array radars, there are also some corresponding shortcomings: 1. The electromagnetic characteristics of each element in the antenna array may be inconsistent due to factors such as ambient temperature and humidity, resulting in array errors, which causes the direction-finding performance of the spatial spectrum estimation algorithm to drop sharply; 2. Although the multiple signal classification subspace method can break through the Rayleigh limit, it is difficult to obtain sufficient independent and identically distributed snapshot data in short-term burst signal environments such as high speed and high maneuverability, resulting in large errors in the estimated covariance matrix or rank loss; 3. In the actual propagation environment of array radars, signals reach the receiving antenna through multiple paths. These multipath signals will form multiple spectral peaks on the DOA spectrum, thereby affecting the direction-finding accuracy. Especially in shipborne and airborne platform applications, due to installation space limitations, there may be scatterers next to the array antenna. These scatterers cannot be detected in real time, resulting in the multipath signals generated. The generated spectral peaks will form interference peaks on the DOA spectrum, and even cause blurring.

[0004] Therefore, a new target radar direction measurement method of array radar is proposed to solve the above problems. Summary of the invention The main purpose of the present invention is to provide a method for measuring the target direction of arrival of an array radar to solve the problems raised in the above background.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for measuring the direction of arrival of a target by an array radar, the method comprising the following implementation steps: Step 1: Configure the IP address information of the array radar remote control area server; Step 2: Enter the environmental warning terminal, monitor environmental parameters in real time, detect whether the electromagnetic characteristics of each element in the antenna array have array errors, mark them when abnormal, and issue warning reminders in real time; Step 3: Enter the independent distribution end, monitor the snapshot data in the short-term burst signal environment in real time, and perform independent and identically distributed classification to achieve independent distribution of the antenna array; Step 4: Enter the multipath adjustment terminal to detect in real time whether there are scatterers around the array antenna, determine whether the phase of the multipath signal and the direct signal is close to the dangerous value, and ensure that the multipath signal direction is clear.

[0006] The environmental early warning terminal includes an array distribution module, an information acquisition module and a characteristic detection module; The array distribution module is used to transmit and receive electromagnetic wave radar through an array composed of several antenna units, form a scanning beam by controlling the signal phase on the antenna unit, set the equidistant array size and array distributed signal receivers, and realize the equidistant distribution of the radar array.

[0007] The information acquisition module includes an environment monitoring unit and a standard value unit; The environmental monitoring unit is used to monitor the environmental parameters of the antenna unit in real time through environmental monitoring equipment, and the environmental monitoring equipment includes imaging laser radar, temperature sensor, humidity sensor, geological radar, network analyzer, plane wave synthesizer, spectrum analyzer, vector network analyzer, signal generator, oscilloscope, thermal imager, radio detection equipment and flow velocity sensor; The standard value unit is used to set the standard phase of the antenna array at the current moment, the waveform and amplitude of the array element output signal, the frequency response, coupling degree, isolation degree and scattering parameters of the array element. The standard value of the array element needs to meet the conditions of S11<-10dB and S21>-0.5dB within the -10dB bandwidth.

[0008] The characteristic detection module includes an array error unit, an error identification unit, an error warning unit and a identification positioning unit; The array error unit is used to calculate the error of the electromagnetic characteristic parameters of the antenna array at the current moment. The calculation formula is as follows:

[0009] in, and They are The amplitude and phase errors of each channel are calculated by calculating the difference between the parameter values ​​monitored by the device at the current moment and the standard parameters. If the difference = 0, the array is judged to be accurate; if the difference ≠ 0, the array is judged to be abnormal. The error identification unit is used to identify the abnormal parameters by color identification, and the error identification is represented by a colored identification point; The error warning unit is used to report abnormal parameters to the system through a voice announcer and issue a voice reminder; The identification and positioning unit is used to locate abnormal parameters in real time through a locator.

[0010] The independent distribution terminal includes a short-time monitoring module, an independent distribution module and a signal classification module; The short-time monitoring module includes a signal snapshot unit and a snapshot recording unit; The signal snapshot unit is used to realize short-time snapshot through single snapshot technology; The snapshot recording unit is used to record the signal data of the short-time snapshot in real time through a data recorder.

[0011] The independent distribution module includes a spatial spectrum estimation unit, which is used to detect the spatial spectrum of the array radar at the current moment in real time through a backward smoothing algorithm. The detection steps are as follows: Step 1: Calculate the sub-definition. The calculation formula is as follows:

[0012] in, is the number of array elements, is the number of signals, Indicates The phase difference of the signals; Step 2: Calculate the correlation matrix, the formula is as follows:

[0013] in, is the number of sub-arrays, It is The covariance of the sub-matrices, when the test result is or When is a full rank matrix, thus avoiding the rank loss problem.

[0014] The signal classification module includes an array independent unit and an independent display unit; The array independent unit is used to reconstruct the covariance matrix of the received data through iterative super-resolution technology, detect the estimated spatial spectrum in real time, and quickly process the single snapshot data through array independent distribution; The independent display unit is used to visually display the single snapshot data in real time through the multi-source data channel.

[0015] The multipath adjustment end includes a scatterer detection module, a phase judgment module and a direction finding and tracking module; The scatterer detection module is used to calculate the radiation field of any point other than the center of the antenna unit. The calculation method is as follows: The antenna array is divided into several small areas with equal diameters in a spherical shape. Each small area is regarded as a single radiation unit. The electromagnetic field amplitude and phase data of each point are measured by scanning at a distance of 3λ to 5λ from the antenna surface.

[0016] in, is in the distance ,angle and The electric field strength at is the expansion coefficient, which contains the amplitude and phase information of the point. is a spherical Hankel function of the second kind, describing radial dependence, is the companion Legendre polynomial, describing Direction dependency, is an exponential term, describing Direction dependency, is the wave number, .

[0017] The phase judgment module includes a multipath phase judgment unit, and the multipath phase judgment unit is used to calculate the phase deviation value. The calculation formula is as follows:

[0018] in, is the multipath signal phase difference at the current moment, is the frequency, It's the time difference.

[0019] The direction finding and tracking module includes a direction finding and tracking unit, an angle adjustment unit and a resolution detection unit; The direction finding and tracking unit is used to track the phase difference at the current moment in real time through a data tracker; The angle adjustment unit is used to automatically adjust the radar measurement angle according to the calculated phase difference; The resolution detection unit is used to calculate the antenna angle resolution at the current moment, and the calculation formula is as follows:

[0020] in, is the angular resolution at the current moment, is the number of receiving antennas at the current moment, is the spacing of the antenna units at the current moment.

[0021] The present invention has the following beneficial effects: 1. In the present invention, by setting an environmental early warning terminal, when measuring the target wave arrival direction of the array radar, by calculating the error of the antenna array parameters in real time, it is detected whether the electromagnetic characteristics of each array element in the antenna array have array errors, so as to avoid the situation where the electromagnetic characteristics of each array element in the antenna array are inconsistent due to factors such as environmental temperature and humidity, causing array errors, and ensure the accuracy of the target wave arrival direction measurement; 2. In the present invention, by setting an independent distribution end, when measuring the target arrival direction of the array radar, by real-time monitoring of snapshot data in a short-term burst signal environment, and combining a backward smoothing algorithm to detect the spatial spectrum of the array radar at the current moment in real time, sufficient independent and identically distributed snapshot data can be obtained when measuring the target arrival direction, avoiding large errors in the estimated covariance matrix or rank loss, and performing real-time detection of the estimated spatial spectrum, thereby increasing the convenience of measuring the target arrival direction; 3. In the present invention, by setting a multipath adjustment end, when measuring the target wave arrival direction of the array radar, by real-time detection of whether there are scatterers around the array antenna, real-time calculation of the phase deviation value, and real-time calculation of the current angular resolution, the generated multipath signal will not form multiple spectral peaks on the DOA spectrum, which can directly avoid rank loss. At the same time, scatterers can be detected in real time to avoid the generated multipath signal from forming spectral peaks with interference properties on the DOA spectrum, thereby preventing the measurement direction and line of sight from being blocked or blurred. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an overall flow chart of a target arrival direction measurement method of an array radar of the present invention; Figure 2 A schematic diagram of the structure of an environment warning end of a target wave arrival direction measurement method of an array radar of the present invention; Figure 3 It is a schematic diagram of the architecture of an independent distribution end of a target arrival direction measurement method of an array radar according to the present invention; Figure 4 The present invention is a schematic diagram of the architecture of a multipath adjustment end of a target arrival direction measurement method of an array radar. DETAILED DESCRIPTION

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0024] Embodiment 1 Please refer to Figure 1-2 As shown: A method for measuring the target direction of arrival of an array radar, the method comprises the following implementation steps: Step 1: Configure the IP address information of the array radar remote control area server; Step 2: Enter the environmental warning terminal, monitor environmental parameters in real time, detect whether the electromagnetic characteristics of each element in the antenna array have array errors, mark them when abnormal, and issue warning reminders in real time; Step 3: Enter the independent distribution end, monitor the snapshot data in the short-term burst signal environment in real time, and perform independent and identically distributed classification to achieve independent distribution of the antenna array; Step 4: Enter the multipath adjustment terminal to detect in real time whether there are scatterers around the array antenna, determine whether the phase of the multipath signal and the direct signal is close to the dangerous value, and ensure that the multipath signal direction is clear.

[0025] The environmental early warning terminal includes an array distribution module, an information acquisition module and a characteristic detection module; The array distribution module is used to transmit and receive electromagnetic wave radar through an array composed of several antenna units, form a scanning beam by controlling the signal phase on the antenna unit, set the equidistant array size and array distributed signal receivers, and realize the equidistant distribution of the radar array.

[0026] The information acquisition module includes an environmental monitoring unit and a standard value unit; The environmental monitoring unit is used to monitor the environmental parameters of the antenna unit in real time through environmental monitoring equipment, and the environmental monitoring equipment includes imaging laser radar, temperature sensor, humidity sensor, geological radar, network analyzer, plane wave synthesizer, spectrum analyzer, vector network analyzer, signal generator, oscilloscope, thermal imager, radio detection equipment and flow velocity sensor; The standard value unit is used to set the standard phase of the antenna array at the current moment, the waveform and amplitude of the array element output signal, the frequency response, coupling degree, isolation degree and scattering parameters of the array element. The standard value of the array element needs to meet the conditions of S11<-10dB and S21>-0.5dB within the -10dB bandwidth.

[0027] The characteristic detection module includes an array error unit, an error identification unit, an error warning unit and an identification positioning unit; The array error unit is used to calculate the error of the electromagnetic characteristic parameters of the antenna array at the current moment. The calculation formula is as follows:

[0028] in, and They are The amplitude and phase errors of each channel are calculated by calculating the difference between the parameter values ​​monitored by the device at the current moment and the standard parameters. If the difference = 0, the array is judged to be accurate; if the difference ≠ 0, the array is judged to be abnormal. The error identification unit is used to identify the abnormal parameters by color identification, and the error identification is represented by a colored identification point; The error warning unit is used to report abnormal parameters to the system through the voice announcer and issue a voice reminder; The identification and positioning unit is used to locate abnormal parameters in real time through a locator.

[0029] By real-time monitoring of environmental parameters and antenna array parameter errors, the electromagnetic characteristics of each element in the antenna array are detected to see if there is an array error, and abnormalities are marked to avoid array errors caused by inconsistent electromagnetic characteristics of each element in the antenna array due to factors such as environmental temperature and humidity, thereby ensuring the accuracy of target wave arrival direction measurement.

[0030] Embodiment 2 Please refer to Figure 3 As shown: Based on the first embodiment, the independent distribution terminal includes a short-time monitoring module, an independent distribution module and a signal classification module; The short-term monitoring module includes a signal snapshot unit and a snapshot recording unit; The signal snapshot unit is used to realize short-time snapshot through single snapshot technology; The snapshot recording unit is used to record the short-time snapshot signal data in real time through a data recorder.

[0031] The independent distribution module includes a spatial spectrum estimation unit, which is used to detect the spatial spectrum of the array radar at the current moment in real time through a backward smoothing algorithm. The detection steps are as follows: Step 1: Calculate the sub-definition. The calculation formula is as follows:

[0032] in, is the number of array elements, is the number of signals, Indicates The phase difference of the signals; Step 2: Calculate the correlation matrix, the formula is as follows:

[0033] in, is the number of sub-arrays, It is The covariance of the sub-matrices, when the test result is or When is a full rank matrix, thus avoiding the rank loss problem.

[0034] The signal classification module includes an array independent unit and an independent display unit; The array independent units are used to reconstruct the covariance matrix of the received data through iterative super-resolution technology, detect the estimated spatial spectrum in real time, and quickly process the single snapshot data through array independent distribution; The independent display unit is used to visualize the single snapshot data in real time through the multi-source data channel.

[0035] By real-time monitoring of snapshot data in a short-term burst signal environment and performing independent and identically distributed classification, the independent distribution of the antenna array is realized. The spatial spectrum of the array radar at the current moment is detected in real time in combination with the backward smoothing algorithm. When measuring the direction of the target radar, sufficient independent and identically distributed snapshot data can be obtained in a short-term burst signal environment such as high speed and high maneuverability, thus avoiding large errors in the estimated covariance matrix or rank loss.

[0036] Embodiment 3 Please refer to Figure 4 As shown: Based on the first embodiment, the multipath adjustment end includes a scatterer detection module, a phase judgment module and a direction finding and tracking module; The scatterer detection module is used to calculate the radiation field of any point other than the center of the antenna unit. The calculation method is as follows: The antenna array is divided into several small areas with equal diameters in a spherical shape. Each small area is regarded as a single radiation unit. The electromagnetic field amplitude and phase data of each point are measured by scanning at a distance of 3λ to 5λ from the antenna surface.

[0037] in, is in the distance ,angle and The electric field strength at is the expansion coefficient, which contains the amplitude and phase information of the point. is a spherical Hankel function of the second kind, describing radial dependence, is the companion Legendre polynomial, describing Direction dependency, is an exponential term, describing Direction dependency, is the wave number, .

[0038] The phase judgment module includes a multipath phase judgment unit, which is used to calculate the phase deviation value. The calculation formula is as follows:

[0039] in, is the multipath signal phase difference at the current moment, is the frequency, It's the time difference.

[0040] The direction finding and tracking module includes a direction finding and tracking unit, an angle adjustment unit and a resolution detection unit; The direction finding and tracking unit is used to track the phase difference at the current moment in real time through the data tracker; The angle adjustment unit is used to automatically adjust the radar measurement angle according to the calculated phase difference; The resolution detection unit is used to calculate the antenna angle resolution at the current moment. The calculation formula is as follows:

[0041] in, is the angular resolution at the current moment, is the number of receiving antennas at the current moment, is the spacing of the antenna units at the current moment.

[0042] By real-time detection of whether there are scatterers around the array antenna, it is determined whether the phase of the multipath signal and the direct signal is close to the dangerous value, and the phase deviation value is calculated in real time, as well as the current angular resolution. When the target wave arrival direction is measured, the multipath signal generated will not form multiple spectral peaks on the DOA spectrum, which can directly avoid rank loss and improve the direction finding accuracy. At the same time, by real-time detection of scatterers around the antenna, the generated multipath signal can be prevented from forming spectral peaks with interference properties on the DOA spectrum.

[0043] In the present invention, a method for measuring the target arrival direction of an array radar comprises the following steps: firstly, configuring the IP address information of the remote control area server of the array radar; entering the environmental warning terminal, monitoring the environmental parameters in real time, detecting whether the electromagnetic characteristics of each array element in the antenna array have array errors, marking them when abnormal, and issuing a warning reminder in real time; when measuring the target arrival direction of the array radar, by monitoring the environmental parameters in real time and the errors of the antenna array parameters in real time, detecting whether the electromagnetic characteristics of each array element in the antenna array have array errors, and marking them when abnormal, avoiding the situation that the electromagnetic characteristics of each array element in the antenna array are inconsistent due to factors such as environmental temperature and humidity, thereby ensuring the accuracy of the target arrival direction measurement and increasing the direction finding performance of the spatial spectrum estimation algorithm; entering the independent distribution terminal, monitoring the snapshot data in a short-time burst signal environment in real time, and performing independent and identically distributed classification to realize the independent distribution of the antenna array; when measuring the target arrival direction of the array radar, by monitoring the snapshot data in a short-time burst signal environment in real time and performing independent and identically distributed classification to realize the independent distribution of the antenna array, combining the backward smoothing algorithm to detect the spatial spectrum of the array radar method at the current moment in real time, so that the target arrival direction measurement is accurate. When measuring, in a short-term burst signal environment such as high speed and high maneuverability, it is also possible to obtain sufficient independent and identically distributed snapshot data to avoid large errors in the estimated covariance matrix or rank loss, and to detect the estimated spatial spectrum in real time, and to quickly process the single snapshot data through the array independent distribution, thereby increasing the convenience of measuring the target arrival direction; entering the multipath adjustment end, it is possible to detect in real time whether there are scatterers around the array antenna, and to determine whether the phase of the multipath signal and the direct signal is close to the dangerous value, to ensure that the multipath signal direction finding is clear, and when measuring the target arrival direction of the array radar, by real-time detection of the array antenna around Whether there are scatterers, determine whether the phase of the multipath signal and the direct signal is close to the dangerous value, and calculate the phase deviation value in real time, as well as the current angular resolution in real time, so that when the target wave arrival direction is measured, the multipath signal generated will not form multiple spectral peaks on the DOA spectrum, which can directly avoid rank loss and thus improve the direction finding accuracy. At the same time, by real-time detection of scatterers around the antenna, an early warning broadcast is immediately issued when a scatterer is detected. Scatterers can be detected in real time to avoid the multipath signal from forming interference spectral peaks on the DOA spectrum, thereby preventing the measurement direction and line of sight from being blocked or blurred.

[0044] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for measuring the direction of arrival of a target using an array radar. It is characterized in that The method comprises the following implementation steps: Step 1: Configure the IP address information of the array radar remote control area server; Step 2: Enter the environmental warning terminal, monitor environmental parameters in real time, detect whether the electromagnetic characteristics of each element in the antenna array have array errors, mark them when abnormal, and issue warning reminders in real time; Step 3: Enter the independent distribution end, monitor the snapshot data in the short-term burst signal environment in real time, and perform independent and identically distributed classification to achieve independent distribution of the antenna array; Step 4: Enter the multipath adjustment terminal to detect in real time whether there are scatterers around the array antenna, determine whether the phase of the multipath signal and the direct signal is close to the dangerous value, and ensure that the multipath signal direction is clear.

2. The method according to claim 1, Features: The environmental early warning terminal includes an array distribution module, an information acquisition module and a characteristic detection module; The array distribution module is used to transmit and receive electromagnetic wave radar through an array composed of several antenna units, form a scanning beam by controlling the signal phase on the antenna unit, set the equidistant array size and array distributed signal receivers, and realize the equidistant distribution of the radar array.

3. The method according to claim 2, Features: The information acquisition module includes an environment monitoring unit and a standard value unit; The environmental monitoring unit is used to monitor the environmental parameters of the antenna unit in real time through environmental monitoring equipment, and the environmental monitoring equipment includes imaging laser radar, temperature sensor, humidity sensor, geological radar, network analyzer, plane wave synthesizer, spectrum analyzer, vector network analyzer, signal generator, oscilloscope, thermal imager, radio detection equipment and flow velocity sensor; The standard value unit is used to set the standard phase of the antenna array at the current moment, the waveform and amplitude of the array element output signal, the frequency response, coupling degree, isolation degree and scattering parameters of the array element. The standard value of the array element needs to meet the conditions of S11<-10dB and S21>-0.5dB within the -10dB bandwidth.

4. The method according to claim 3, Features: The characteristic detection module includes an array error unit, an error identification unit, an error warning unit and a identification positioning unit; The array error unit is used to calculate the error of the electromagnetic characteristic parameters of the antenna array at the current moment. The calculation formula is as follows: in, and They are The amplitude and phase errors of each channel are calculated by calculating the difference between the parameter values ​​monitored by the device at the current moment and the standard parameters. If the difference = 0, the array is judged to be accurate; if the difference ≠ 0, the array is judged to be abnormal. The error identification unit is used to identify the abnormal parameters by color identification, and the error identification is represented by a colored identification point; The error warning unit is used to report abnormal parameters to the system through a voice announcer and issue a voice reminder; The identification and positioning unit is used to locate abnormal parameters in real time through a locator.

5. The method according to claim 1, Features: The independent distribution terminal includes a short-time monitoring module, an independent distribution module and a signal classification module; The short-time monitoring module includes a signal snapshot unit and a snapshot recording unit; The signal snapshot unit is used to realize short-time snapshot through single snapshot technology; The snapshot recording unit is used to record the signal data of the short-time snapshot in real time through a data recorder.

6. The method according to claim 5, Features: The independent distribution module includes a spatial spectrum estimation unit, which is used to detect the spatial spectrum of the array radar at the current moment in real time through a backward smoothing algorithm. The detection steps are as follows: Step 1: Calculate the sub-definition. The calculation formula is as follows: in, is the number of array elements, is the number of signals, Indicates The phase difference of the signals; Step 2: Calculate the correlation matrix, the formula is as follows: in, is the number of sub-arrays, It is The covariance of the sub-matrices, when the test result is or When is a full rank matrix, thus avoiding the rank loss problem.

7. The method according to claim 6, Features: The signal classification module includes an array independent unit and an independent display unit; The array independent unit is used to reconstruct the covariance matrix of the received data through iterative super-resolution technology, detect the estimated spatial spectrum in real time, and quickly process the single snapshot data through array independent distribution; The independent display unit is used to visually display the single snapshot data in real time through the multi-source data channel.

8. The method according to claim 1, Features: The multipath adjustment end includes a scatterer detection module, a phase judgment module and a direction finding and tracking module; The scatterer detection module is used to calculate the radiation field of any point other than the center of the antenna unit. The calculation method is as follows: The antenna array is divided into several small areas with equal diameters in a spherical shape. Each small area is regarded as a single radiation unit. The electromagnetic field amplitude and phase data of each point are measured by scanning at a distance of 3λ to 5λ from the antenna surface. in, is in the distance ,angle and The electric field strength at is the expansion coefficient, which contains the amplitude and phase information of the point. is a spherical Hankel function of the second kind, describing radial dependence, is the companion Legendre polynomial, describing Direction dependency, is an exponential term, describing Direction dependency, is the wave number, .

9. The method according to claim 8, Features: The phase judgment module includes a multipath phase judgment unit, and the multipath phase judgment unit is used to calculate the phase deviation value. The calculation formula is as follows: in, is the multipath signal phase difference at the current moment, is the frequency, It's the time difference.

10. The method according to claim 9, Features: The direction finding and tracking module includes a direction finding and tracking unit, an angle adjustment unit and a resolution detection unit; The direction finding and tracking unit is used to track the phase difference at the current moment in real time through a data tracker; The angle adjustment unit is used to automatically adjust the radar measurement angle according to the calculated phase difference; The resolution detection unit is used to calculate the antenna angle resolution at the current moment, and the calculation formula is as follows: in, is the angular resolution at the current moment, is the number of receiving antennas at the current moment, is the spacing of the antenna units at the current moment.

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