A dual-target joint steering vector channel phase correction method

Abstract

This invention provides a channel phase correction method based on a dual-target joint steering vector, comprising using singular value features based on the covariance matrix of array sampled signals for single-source identification. A dual-target joint search method is employed for the selected single sources, considering single sources from two directions. By combining these two single sources and dividing the signals from the same antenna, the amplitude-phase inconsistency vector of the array can be deducted, resulting in a definite joint signal. The joint signal model eliminates the amplitude-phase inconsistency of the array, and the two directions of the single source can be determined through a two-dimensional azimuth search. After determining these two azimuths, the amplitude-phase inconsistency vector of the array can be determined. As many single sources as possible are obtained, and multiple sets of phase correction values ​​are obtained for each set of single-source signals. Finally, the mode of the multiple phase correction values ​​is taken as the final phase correction value. This invention does not require the introduction of new equipment, increasing the complexity of equipment and signal processing, and is a more economical channel phase correction solution.

Description

Technical Field

[0001] This invention belongs to the field of radar signal processing, and particularly relates to a channel phase correction method for a joint steering vector of two targets. Background Technology

[0002] Ground-wave radar utilizes the low attenuation and long propagation distance of vertically polarized high-frequency electromagnetic waves at the sea surface to detect ships, aircraft, missiles, and other objects below the line of sight at sea level. By employing the first and second-order scattering mechanisms of high-frequency electromagnetic waves with the sea surface, wind, wave, and current field information can be extracted from radar echoes, enabling large-scale, high-precision, and all-weather detection of the marine environment. Because ground-wave radar operates in the high-frequency band (3-30MHz), its corresponding wavelength (300-30m) is relatively long. To obtain sufficient array gain and angular resolution, the array length is typically hundreds or even thousands of meters. Accurate radar array manifolds are required when using the Multiple Signal Classification (MUSIC) algorithm for angle of arrival (DOA) estimation. However, in practical engineering applications, various errors and disturbances are unavoidable, causing deviations in the array manifold matrix elements, which in turn affect the accuracy of the spatial spectrum estimation results. In severe cases, this can lead to estimated DOA results deviating significantly from the true value. Therefore, amplitude and phase calibration of the array channels is necessary.

[0003] Channel correction typically involves knowing the information of the cooperating source, i.e., knowing the signal source with the azimuth of the incoming wave from the target beforehand. While using cooperating sources for correction yields reliable results, the introduction of new equipment increases the complexity of ground wave radar systems. Ground wave radar exhibits strong first-order echoes due to Bragg scattering. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of array channel phase calibration in high-frequency ground wave radar and to provide a channel phase correction method for dual-target joint steering vector.

[0005] The present invention adopts the following technical solution:

[0006] A method for channel phase correction of a dual-target joint steering vector includes the following steps:

[0007] Step 1. Use the singular value features based on the covariance matrix of the array sampled signal to determine the single source.

[0008] Step 2. Use a dual-target joint search method for the selected single information sources, considering single information sources from two directions.

[0009] Step 3. By combining the two single signal sources and dividing the signals from the same antenna, the amplitude-phase inconsistency vector of the receiving array can be subtracted, thus obtaining a definite joint signal.

[0010] Step 4. The joint signal model eliminates the amplitude and phase inconsistency of the array, and the two directions of a single signal source can be determined by a two-dimensional orientation search.

[0011] Step 5. After determining these two orientations, the amplitude-phase inconsistency vector of the receiving array can be determined.

[0012] Step 6. Obtain as many single signal sources as possible, obtain multiple phase correction values ​​for each single signal source, and finally take the mode of multiple phase correction values ​​as the final phase correction value.

[0013] The beneficial effects of this invention are:

[0014] Compared to direct wave correction, this invention uses first-order spectrum correction, eliminating the need for external equipment and providing an economical solution. Unlike previous methods that obtain channel phase correction values ​​based on a single source's first-order echo, this invention employs a dual-target joint search scheme. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the implementation of the present invention;

[0016] Figure 2 The phase correction values ​​are for the Dongshan direct wave, the Chihu direct wave, and the first-order spectrum;

[0017] Figure 3 (a) is the phase correction value of the direct wave from Dongshan during the No. 8 antenna experiment;

[0018] Figure 3 (b) is the phase correction value of the direct wave to Chihu Lake during the experiment with antenna No. 8;

[0019] Figure 3 (c) represents the first-order spectrum phase correction value during the experiment of antenna No. 8. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] like Figure 1 As shown, a channel phase correction method for a dual-target joint steering vector includes the following steps:

[0022] Step 1. Use singular value features based on the covariance matrix of the array sampled signal to determine the single source;

[0023] Assumption The coordinates of the elementary planar matrix are as follows:

[0024] (1)

[0025] (2)

[0026] for The coordinates of antenna number are defined in the EN coordinate system. Let represent the transpose of the matrix. Then the ideal received signal of the receiving array is...

[0027] (3)

[0028] This indicates the angle at which the target rotates northward relative to the due east direction. It is the real-time amplitude of the signal. It is the real-time phase of the signal. Represents the imaginary unit. Let be the spatial wavenumber of the electromagnetic wave. The amplitude-phase inconsistency vector of the receiving array is defined as .

[0029] (4)

[0030] The task of channel correction is to solve Using antenna number one as a reference, and Let the amplitude ratio and phase difference of the signal received with antenna 1 as the standard be respectively. and Considering the amplitude-phase inconsistency of the receiving array, the vector signal received by the receiving array can be expressed as:

[0031] (5)

[0032] This is the ideal signal received by the receiving array.

[0033] An array signal with amplitude and phase errors can be represented as follows:

[0034] (6)

[0035] in, for 3D data vector; express 3D amplitude phase error matrix; Indicates from Direction Dimensional signal; express 3D spatial array guide vector; express 3D noise signal;

[0036] The array covariance matrix is ​​represented as follows:

[0037] (7).

[0038] in, Indicates signal power; Indicates noise power. It is a unit vector; This indicates the calculation of the expected value. Indicates conjugate transpose;

[0039] Eigenvalue decomposition of the array covariance matrix R yields the eigenvector corresponding to the largest eigenvalue. The relationship between the signal steering vector and the signal steering vector is as follows:

[0040] (8)

[0041] in Let be an unknown complex constant, from the above equation we get ,

[0042] This allows us to determine if there is a single source in the echo.

[0043] Step 2. Apply a dual-objective joint search method to the selected single information sources, considering single information sources from two directions. and The single source receives signals as follows:

[0044] (9)

[0045] (10)

[0046] in, For the receiving array received from Ideal signal reception direction For the receiving array received from Ideal signal reception in the direction.

[0047] (11)

[0048] (12)

[0049] in, and This indicates the angle at which the target rotates northward relative to the due east direction. and It is the real-time amplitude of the signal. and It is the real-time phase of the signal. Represents the imaginary unit. is the spatial wavenumber of electromagnetic waves.

[0050] Step 3. By combining the two single signal sources and dividing the signals from the same antenna, the amplitude-phase inconsistency vector of the receiving array can be subtracted. The determined joint signal model is as follows:

[0051] (13)

[0052] Step 4. The joint signal model eliminates the amplitude-phase inconsistency of the array, and the two directions of a single signal source can be determined through a two-dimensional orientation search. and .

[0053] Step 5. After determining these two orientations, the amplitude-phase inconsistency vector of the receiving array can be determined. Subtracting the ideal steering vector, the amplitude-phase inconsistency vector can then be solved.

[0054] (14)

[0055] in, To receive the vector signal received by the receiving array, This indicates the angle at which the target rotates northward relative to due east. and The coordinates of antenna 1 are defined in the EN coordinate system.

[0056] It is important to note that In the replacement (13) ,at the same time In the replacement (13) The joint signal model remains unchanged. This indicates that there is ambiguity in using a dual-objective joint search, and the angle... and There are two fuzzy angles of "translation-exchange". and Ground-wave radar is usually located on the shore, and the radar's field of view is often smaller than that of land-based radar. This ambiguity can be avoided by limiting the search range of angles.

[0057] Step 6. The floating platform ground wave radar has echoes in all directions, and the ambiguity problem can be solved by the mode estimation of multiple sets of measurement results.

[0058] Phase correction using first-order spectral signals differs from amplitude correction. Amplitude correction does not require the selected first-order spectral signal to be a single source, but phase correction does. Single-source identification is performed using singular value features based on the covariance of the array sampled signal. Using the selected single sources, channel phase correction can be performed using the dual-objective joint search theory. In practical signal processing, the number of single sources should be as large as possible. For each set of single-source signals, multiple phase correction values ​​can be obtained, and the mode of these multiple phase correction values ​​is used as the final phase correction value.

[0059] Instance verification

[0060] In January 2016, the Oceanographic Laboratory of Wuhan University conducted a ground-to-surface radar network experiment in Wuhan, Hubei Province, and Longhai, Chihu, and Dongshan, Fujian Province. The ground-to-surface receiving stations were located in Longhai, Chihu, and Dongshan, Fujian Province. The measured data analysis utilized radar data received in Dongshan and Chihu during the experiment, with a single-field coherent accumulation time of 5 minutes.

[0061] As attached Figure 2 The phase correction values ​​of all eight antennas during the experiments at Dongshan and Chihu were statistically analyzed. The maximum error of the two direct wave correction results was... The maximum error between the first-order spectrum and the Dongshan direct wave correction value is... The minimum error is The maximum error between the first-order spectrum and the correction value of the direct wave from Chihu Lake is... The minimum error is The first-order spectrum can yield phase correction results close to those of the direct wave, but its error is larger compared to the direct wave. The phase correction values ​​of the direct wave and the first-order spectrum were statistically analyzed throughout the experiment, and their frequency distribution histograms were obtained as follows. Figure 3 (a)- Figure 3 As shown in (c), the correction results for the Chihu direct wave and the Dongshan direct wave are highly concentrated, and their consistency is good. The correction results for the first-order spectrum are basically unbiased compared to the correction results for the direct wave, but their distribution range is larger. Although the correction stability and reliability of the direct wave are higher than those of the first-order spectrum, the first-order spectrum does not require the introduction of external equipment, providing an economical solution. Unlike previous methods for obtaining channel phase correction values ​​based on optimization schemes of single-source first-order echoes, the dual-target joint search scheme is an analytical method.

[0062] This paper demonstrates the approach and theoretical basis for channel amplitude correction using antenna statistical energy, and successfully obtains stable antenna amplitude correction results using first-order spectral data. Simultaneously, the dual-target joint search theory is introduced into ground wave radar channel correction, and channel phase correction is achieved using first-order ocean echoes. Furthermore, it points out that using the mode of multiple sets of measurements can effectively solve the "translation-commutation" angle ambiguity problem in the azimuth search phase of this method. The proposed method has the potential to provide stable correction results within a short time of five minutes.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for channel phase correction of a dual-target joint steering vector, characterized in that, Includes the following steps: Step 1. Use singular value features based on the covariance matrix of the array sampled signal to determine the single source; Step 2. For the selected single information sources, employ a dual-objective joint search method, considering single information sources from two directions. and The received signals from the single source are as follows: （9） （10） in, For the receiving array received from Ideal signal reception direction For the receiving array received from Ideal signal reception direction （11） （12） in, and This indicates the angle at which the target rotates northward relative to due east. and It is the real-time amplitude of the signal. and It is the real-time phase of the signal. Represents the imaginary unit. is the spatial wave number of electromagnetic waves; Step 3. Combine the two single signal sources and divide the signals from the same antenna to subtract the amplitude-phase inconsistency vector of the receiving array. The determined joint signal model is as follows: （13） Step 4. The joint signal model eliminates the amplitude-phase inconsistency of the array, and the two directions of a single signal source are determined through a two-dimensional orientation search. and ; Step 5. After determining these two orientations, the amplitude-phase inconsistency vector of the array is determined. After subtracting the ideal steering vector, the amplitude-phase inconsistency vector of the receiving array is solved: （14） in, To receive the vector signal received by the receiving array, This indicates the angle at which the target rotates northward relative to due east. and The coordinates of antenna No. 1 are defined in the EN coordinate system. Step 6. The floating platform ground wave radar has echoes in all directions. The ambiguity problem is solved by the mode estimation of multiple sets of measurement results.

2. The channel phase correction method for the dual-target joint steering vector according to claim 1, characterized in that, Step 1 is as follows: Assumption The coordinates of the primitive planar matrix are as follows: （1） （2） for The coordinates of antenna number are defined in the EN coordinate system. Let the transpose of the matrix be represented, then the ideal received signal of the receiving array is: （3） This indicates the angle at which the target rotates northward relative to due east. It is the real-time amplitude of the signal. It is the real-time phase of the signal. Represents the imaginary unit. Let the spatial wavenumber of the electromagnetic wave be denoted as the amplitude-phase inconsistency vector of the receiving array: （4） The task of channel correction is to solve Using antenna number one as a reference, and Let the amplitude ratio and phase difference of the signal received with antenna 1 as the standard be respectively. and Considering the inconsistency between amplitude and phase of the receiving array, the vector signal received by the receiving array is represented as: （5） For the ideal received signal of the receiving array; An array signal with amplitude and phase errors is represented as follows: （6） in, for 3D data vector; express 3D amplitude phase error matrix; Indicates from Direction Dimensional signal; express 3D spatial array guide vector; express 3D noise signal; The array covariance matrix is ​​represented as follows: （7） in, Indicates signal power; Indicates noise power. It is a unit vector; This indicates the calculation of the expected value. Indicates conjugate transpose; Eigenvalues ​​corresponding to the largest eigenvalues ​​are obtained by performing eigenvalue decomposition on the array covariance matrix R. The relationship between the signal steering vector and the signal steering vector is as follows: （8） in, Let be an unknown complex constant, from the above equation we get , This indicates a single source in the echo.

3. The channel phase correction method for the dual-target joint steering vector according to claim 1, characterized in that, Step 5 also includes: It is important to note that In the replacement (13) ,at the same time In the replacement (13) The joint signal model remains unchanged, indicating that there is ambiguity in using a dual-objective joint search. and There are two fuzzy angles of "translation-exchange". and Ground wave radars are usually located on the shore, and the field of view of shore-based radars is often smaller than that of ground wave radars. This avoids such ambiguity by limiting the search range of angles.

4. The channel phase correction method for the dual-target joint steering vector according to claim 1, characterized in that, Step 6 specifically involves using a first-order spectral signal for phase correction, which differs from amplitude correction. Amplitude correction does not require the selected first-order spectral signal to be a single source, but phase correction does. Singular value features based on the covariance of the array sampled signal are used to determine the single source. Using the selected single source, channel phase correction is performed using the dual-objective joint search theory. In the actual signal processing, the number of single sources should be as large as possible. Multiple phase correction values ​​are obtained for each set of single source signals, and the mode of the multiple phase correction values ​​is used as the final phase correction value.

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