Method and device for estimating arrival angle of high-robustness floating high-frequency ground wave radar point targetTechnical Field
The invention belongs to the technical field of radar array signal processing, and particularly relates to a method and a device for estimating an arrival angle of a high-robustness floating high-frequency ground wave radar point target.
Background
Due to the beyond-the-horizon detection characteristic of the high-frequency ground wave radar, all-weather and high-precision monitoring of an economic exclusive area within the range of 200 sea can be realized. In order to further expand the application scenario of the radar, making it go to deep blue, it is extremely necessary to develop a floating high-frequency ground wave radar. The floating high-frequency ground wave radar has no coastline constraint, has wider detection range and can save precious coastal travel and cultivation land resources. The floating high-frequency ground wave radar can also be used as a dynamic node of a high-frequency ground wave radar networking system, and the detection capability of the existing high-frequency ground wave radar networking system can be further improved. However, yaw rotation of the floating high frequency ground wave radar over a generally relatively long period of several minutes of coherent integration time can result in reduced accuracy in estimating the angle of arrival of the point target.
K.w.gurgel (1989), tian Yingwei (2013) and Xie Junhao (2016) all control the floating platform to advance at a uniform speed to avoid yaw rotation. Wu Xiong (2016) attempted to anchor a floating platform at sea, uncontrollable yaw rotation became a key factor limiting the accuracy of angle-of-arrival estimation. For yaw compensation, the subject set performs adaptive beamforming in combination with measured yaw angles so that the real-time beam and the reference beam can be kept consistent as yaw rotates. The method can effectively compensate yaw rotation and improve the accuracy of arrival angle estimation, but with the existence of different array types and antenna pattern distortion, the arrival angle estimation of a target point after yaw compensation still has deviation, and the signal-to-noise ratio of a signal after compensation is reduced, so that the robustness is difficult to guarantee.
Disclosure of Invention
The method aims at the problem that when adaptive beam forming is used for carrying out yaw compensation on the floating high-frequency ground wave radar, the robustness of arrival angle estimation is difficult to guarantee when array type differences and antenna pattern distortion exists. Firstly, determining an angle focusing length and an angle focusing center to determine an angle constraint range of self-adaptive beam forming, secondly, obtaining a self-adaptive weight vector of balanced focusing by considering the balance of a noise power gain and a beam maintaining factor in the angle constraint range, secondly, restraining the noise power gain to be lower than 0dB to obtain the self-adaptive weight vector without signal-to-noise ratio loss and with smaller angle constraint range, finally, performing yaw compensation by using the self-adaptive weight vector through beam forming, obtaining an arrival angle estimation result after performing yaw compensation through a MUSIC (MultipleSignalClassification) algorithm of a beam space, and gradually iterating to obtain a point target arrival angle estimation result with high robustness by taking the estimated arrival angle as a new angle focusing center and reducing the angle focusing length.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method for estimating an arrival angle of a point target of a high-robustness floating high-frequency ground wave radar, comprising the steps of:
(1) Determining angle focusing length thetal and angle focusing center thetac in the iterative process, wherein the angle focusing length is 360° in the first iteration, the angle focusing center is the arrival angle estimation result obtained by using conventional beam forming, and the angle focusing length is 360 in the second iterationThe angle focusing center takes the angle focusing length asThe arrival angle estimation result after time compensation is T is the iteration number;
Wherein, the
K denotes the kth beam channel, K is the number of beam channels, K is also the number of antenna channels, k=1, 2,..k, w0k is the reference weight vector,For a real-time yaw angle,For a reference yaw angle over a coherent integration time, ζ is a balance factor describing noise power gain and beam-holding factor contribution weights, θ is azimuth,As a reference beam,For a real-time array steering vector,The vector is directed for the reference array,AndThe following are listed below
Wherein, the
K0 is the wave number of the working electromagnetic wave,Is a unit guiding vector in the theta direction, Ar0 is a coordinate matrix of a receiving antenna array, ar0k is a three-dimensional coordinate vector of a k-number antenna, Xr0k is an X-axis coordinate, Yr0k is a Y-axis coordinate, Zr0k is a Z-axis coordinate,To describe the rotation matrix of the real-time yaw rotation,A rotation matrix describing a reference yaw rotation;
(3) The values of the noise power gain and the beam holding factor corresponding to different balance factors are calculated, and the noise power gain calculation method is as follows:
The method for calculating the beam holding factor is as follows:
Wherein, the
Selecting a balance factor value range with noise power gain smaller than 0dB for self-adapting wave beam to avoid signal-to-noise ratio loss, then determining balance factor xiD with minimum wave beam holding factor in the value range, and self-adapting weight vectorThe adaptive weight vector with high robustness is obtained;
(4) And carrying out beam forming on the sampling data of the antenna channel by using the obtained high-robustness self-adaptive weight vector to obtain compensation data of the beam channel, and estimating the arrival angle of the floating high-frequency ground wave radar point target through a MUSIC algorithm of a beam space. The point target arrival angle after yaw compensation is used as a new angle focusing center, the angle focusing length is further reduced, and the whole process is repeated to obtain a point target arrival angle estimation result with higher robustness.
In one embodiment of the present invention, the step (4) specifically includes:
a total of K reference beams are determined as follows:
computing a corresponding highly robust adaptive weight vector for each reference beamAnd then carrying out arrival angle estimation on the beam channel compensation data by using a MUSIC angle searching method based on the beam channel, wherein the method comprises the following steps:
UBN is a KXMn matrix formed by using eigenvectors corresponding to noise subspaces of beam channel compensation data, Mn is the dimension of the noise subspaces, Mn is more than or equal to 1 and less than or equal to K-1, the peak value of PMUSIC (theta) is searched to obtain an arrival angle estimation result of the yaw compensated signal, all the steps are repeatedly executed, and the arrival angle estimation result output by the T-th repeated execution is a final arrival angle estimation result.
According to another aspect of the present invention, there is provided a device for estimating an arrival angle of a high-robustness floating high-frequency ground wave radar point target, including at least one processor and a memory, the at least one processor and the memory being connected by a data bus, the memory storing instructions executed by the at least one processor, the instructions, after being executed by the processor, being configured to complete the method for estimating an arrival angle of a high-robustness floating high-frequency ground wave radar point target.
In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:
(1) When the balance factor is zero and the angle constraint range is 360 degrees, the invention is the background technology for only constraining the beam maintaining factor, and is a scheme with stronger universality;
(2) The method can avoid the loss of signal to noise ratio caused by restraining the beam retention factor only, and is more suitable for estimating the arrival angle of the weak target echo of the floating high-frequency ground wave radar;
(3) The smaller angle constraint range enables the self-adaptive beam forming to have stronger control capability on the beam, and can improve the robustness of the estimation of the arrival angle of the target of the points such as an airplane, a ship and the like.
Drawings
Fig. 1 is a schematic flow chart of a method for estimating a target arrival angle of a high-robustness floating high-frequency ground wave radar point in the invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The invention aims to provide a high-robustness self-adaptive beam forming scheme which is applicable to yaw compensation of a floating high-frequency ground wave radar, wherein the technical problems to be solved include (1) determination of an angle focusing length and an angle focusing center in an iterative process of the high-robustness self-adaptive beam forming, (2) calculation of a self-adaptive weight vector for balanced focusing, (3) determination of a balance factor corresponding to the self-adaptive weight vector which has no signal to noise ratio loss and has a smaller angle constraint range, and (4) arrival angle estimation of a beam space.
In order to solve the technical problems, the invention provides a high-robustness floating high-frequency ground wave radar point target arrival angle estimation method, which comprises the following steps:
(1) Determining angle focusing length thetal and angle focusing center thetac in the iterative process, wherein the angle focusing length is 360 DEG in the first iteration, the angle focusing center is the arrival angle estimation result obtained by using conventional beam forming, and the angle focusing length is obtained when the steps are repeatedly executed againThe angle focusing center takes the angle focusing length asThe arrival angle estimation result after time compensation is T is the iteration number;
(2) According to the determined angle focusing length and angle focusing center, obtaining the self-adaptive weight vector of balanced focusing as
Wherein, the
K denotes the kth beam channel, K is the number of beam channels, K is also the number of antenna channels, k=1, 2,..k, w0k is the reference weight vector,For a real-time yaw angle,For a reference yaw angle over a coherent integration time, ζ is a balance factor describing noise power gain and beam-holding factor contribution weights, θ is azimuth,As a reference beam,For a real-time array steering vector,The vector is directed for the reference array,AndThe following are listed below
Wherein, the
K0 is the wave number of the working electromagnetic wave,Is a unit guiding vector in the theta direction, Ar0 is a coordinate matrix of a receiving antenna array, ar0k is a three-dimensional coordinate vector of a k-number antenna, Xr0k is an X-axis coordinate, Yr0k is a Y-axis coordinate, Zr0k is a Z-axis coordinate,To describe the rotation matrix of the real-time yaw rotation,A rotation matrix describing a reference yaw rotation;
(3) The values of the noise power gain and the beam holding factor corresponding to different balance factors are calculated, and the noise power gain calculation method is as follows:
The method for calculating the beam holding factor is as follows:
Wherein, the
Selecting a balance factor value range with noise power gain smaller than 0dB for self-adapting wave beam to avoid signal-to-noise ratio loss, then determining balance factor xiD with minimum wave beam holding factor in the value range, and self-adapting weight vectorThe high robustness self-adaptive weight vector is obtained;
(4) And carrying out beam forming on the sampling data of the antenna channel by using the obtained high-robustness self-adaptive weight vector to obtain compensation data of the beam channel, and estimating the arrival angle of the floating high-frequency ground wave radar point target through a MUSIC algorithm of a beam space. The point target arrival angle after yaw compensation is used as a new angle focusing center, the angle focusing length is further reduced, and the whole process is repeated to obtain a point target arrival angle estimation result with higher robustness.
Specifically, the arrival angle of a floating high-frequency ground wave radar point target is estimated through a MUSIC algorithm of a beam space, specifically, K reference beams are determined in total, and the method is as follows:
computing a corresponding highly robust adaptive weight vector for each reference beamAnd then carrying out arrival angle estimation on the beam channel compensation data by using a MUSIC angle searching method based on the beam channel, wherein the method comprises the following steps:
UBN is a KXMn matrix formed by using eigenvectors corresponding to noise subspaces of beam channel compensation data, Mn is the dimension of the noise subspaces, Mn is more than or equal to 1 and less than or equal to K-1, the peak value of PMUSIC (theta) is searched to obtain an arrival angle estimation result of the yaw compensated signal, all the steps are repeatedly executed, and the arrival angle estimation result output by the T-th repeated execution is a final arrival angle estimation result.
The invention further provides a high-robustness floating high-frequency ground wave radar point target arrival angle estimation device, which comprises at least one processor and a memory, wherein the at least one processor and the memory are connected through a data bus, the memory stores instructions executed by the at least one processor, and the instructions are used for completing the high-robustness floating high-frequency ground wave radar point target arrival angle estimation method after being executed by the processor.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.