阅读说明：本技术 一种基于图信号处理的雷达目标距离估计方法 (Radar target distance estimation method based on graph signal processing ) 是由 廖可非 余泽锐 蒋俊正 谢宁波 王海涛 欧阳缮 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种基于图信号处理的雷达目标距离估计方法,该方法对所有阵元进行图信号构建,使两两阵元之间的相位信息能够在图傅里叶变换中起更好的特征分解的作用从而获得更好的目标距离估计结果,并使用多个单频信号完成频率分集宽带信号的合成,完成了多目标距离估计,降低了系统复杂度。采用全连接的邻接矩阵As图信号的方式进行目标距离估计,时间和空间复杂度与稀疏连接图信号目标距离估计方法一样,得到的结果归一化结果更好,引入图信号处理的方法用于目标距离估计中,得到新的目标距离估计方法,通过加入阵元排列下阵元之间的位置差关系对方位向进行估计,达到联合估计的效果。(The invention discloses a radar target distance estimation method based on graph signal processing, which constructs graph signals for all array elements, enables phase information between every two array elements to play a better characteristic decomposition role in graph Fourier transform so as to obtain a better target distance estimation result, completes synthesis of frequency diversity broadband signals by using a plurality of single-frequency signals, completes multi-target distance estimation and reduces system complexity. The target distance estimation is carried out by adopting a fully-connected adjacent matrix As image signal mode, the time and space complexity is the same As that of a sparse connection image signal target distance estimation method, the obtained result normalization result is better, an image signal processing method is introduced to be used in the target distance estimation to obtain a new target distance estimation method, the azimuth is estimated by adding the position difference relation between array elements under array element arrangement, and the effect of joint estimation is achieved.)

1. A radar target distance estimation method based on graph signal processing is characterized by comprising the following steps:

1) radar generation f_iStepped frequency signalAnd transmitting the signal to the target, wherein I is 1,2 … I, I is the number of frequency points, f_i＝f_c+ i.Deltaf parallel time array elements are transmitted simultaneously, i is the frequency point number, f_cAs a single-frequency baseband signal, Δ f is a fixed frequency increment;

2) after radar signals are reflected by a target, a receiving antenna receives a reflected echo signal of the target, the reflected echo signal is collected by a data acquisition card, and the target echo signal is expressed as follows:

wherein delta_mM is 1,2 … M for the scattering coefficient of each target, wherein M is the number of targets, noise (t-tau) represents additive noise after time delay, and tau represents echo phase difference caused by different distances in multiple targetsc represents the speed of light, R_iRepresents the distance of the mth target;

3) arranging the phase information of different frequencies of the received target echo signals into a matrix to obtain an adjacent matrix A_s：

Wherein Δ f_i,jArray element for representing ith frequency point and jth frequency pointThe step frequency difference of the array element;

4) according to the orthogonality of echo signals and noise subspaces, the adjacent matrix A is reversely solved_sExpression (c): a. the_sx is x to obtain A_sElements of each row of the diagram signal

5) According to the theorem of feature decomposition, the adjacent matrix A_sPerforming subspace decomposition to obtain a graph Fourier operator

6) Echo signal S of the pair of image Fourier operators_m(t) performing a Fourier transform of the image to obtain a Fourier form of the image of the echo signal

7) Method function F for estimating target distance by minimizing map signal_GSP(R), removing M +1 minimum values, and taking the reciprocal of the two-norm to obtain the final distance direction estimation result as follows:

Technical Field

The invention relates to the technical field of radar signal processing, in particular to a radar target distance estimation method based on graph signal processing.

Background

The estimation of the direction of arrival is one of the most important tasks in the field of array signal processing in recent decades, with the continuous development and application of algorithm technology in decades, the estimation of the direction of arrival has made a great breakthrough and development, and particularly, MUSIC, ESPRIT and the like decompose algorithms in subspace, and the algorithms break through the Reynaud limit to meet the performance requirement of super resolution, thereby not only greatly improving the capability of radar searching for a target, but also providing a new field of subspace for DoA research, which is a milestone in the history of array signal processing. The DoA estimation of radar array signals can perform parameter estimation on targets in a space domain, such as distance, azimuth angle, pitch angle and the like, and is an extremely important target estimation method in both the military communication field and the traditional civil communication field. For example, the DoA estimation is not needed to be carried out when parameter information of an enemy target is obtained for reconnaissance or when the position of a user is obtained, the DoA estimation also becomes a spatial spectrum estimation, namely the total energy distribution performance of a signal in a space domain, namely the parameter information of a signal source is obtained by analyzing the spatial spectrum distribution and the structure of a received signal, the traditional MUSIC algorithm and the ESPRIT algorithm have large positioning error in the environment with low signal-to-noise ratio, the phase information of the received signal of each array element is not fully utilized, and the like, and people put more attention on the two directions of improving a subspace algorithm and an array structure to improve the performance of the DoA algorithm.

Disclosure of Invention

The invention aims to solve the problems of how to improve the performance of target distance estimation under low signal-to-noise ratio and how to increase the utilization rate of frequency point phase information, and provides a radar target distance estimation method based on graph signal processing.

The technical scheme for realizing the purpose of the invention is as follows:

a radar target distance estimation method based on graph signal processing comprises the following steps:

1) radar generation f_iStepped frequency signalAnd transmitting the signal to the target, wherein I is 1,2 … I, I is the number of frequency points, f_i＝f_c+ i.Deltaf parallel time array elements are transmitted simultaneously, i is the frequency point number, f_cAs a single-frequency baseband signal, Δ f is a fixed frequency increment;

2) after radar signals are reflected by a target, a receiving antenna receives a reflected echo signal of the target, the reflected echo signal is collected by a data acquisition card, and the target echo signal is expressed as follows:

wherein delta_mM is 1,2 … M for the scattering coefficient of each target, wherein M is the number of targets, noise (t-tau) represents additive noise after time delay, and tau represents echo phase difference caused by different distances in multiple targetsc represents the speed of light, R_iRepresents the distance of the mth target;

3) arranging the phase information of different frequencies of the received target echo signals into a matrix to obtain an adjacent matrix A_s：

Wherein Δ f_i,jThe step frequency difference of the array element of the ith frequency point and the array element of the jth frequency point is represented;

4) according to the orthogonality of echo signals and noise subspaces, the adjacent matrix A is reversely solved_sExpression (c): a. the_sx is x to obtain A_sElements of each row of the diagram signal

5) According to the theorem of feature decomposition, the adjacent matrix A_sPerforming subspace decomposition to obtain a graph Fourier operator

6) Echo signal S of the pair of image Fourier operators_m(t) performing a Fourier transform of the image to obtain a Fourier form of the image of the echo signal

7) Method function F for estimating target distance by minimizing map signal_GSP(R), removing M +1 minimum values, and taking the reciprocal of the two-norm to obtain the final distance direction estimation result as follows:

compared with the prior art, the radar target distance estimation method based on graph signal processing has the following beneficial effects:

(1) the method comprises the steps of constructing image signals for all array elements, enabling phase information between every two array elements to have a better characteristic decomposition effect in image Fourier transform so as to obtain a better target distance estimation result, completing synthesis of frequency diversity broadband signals by using a plurality of single-frequency signals, completing multi-target distance estimation, and reducing system complexity.

(2) Using fully-connected adjacency matrices A_sThe target distance estimation is carried out in a graph signal mode, the time and space complexity is the same as that of a sparse connection graph signal target distance estimation method, the obtained result normalization result is better, and compared with the sparse connection graph signal target distance estimation method, the method has steeper peak and larger-3 dB attenuation.

(3) The method of image signal processing is introduced to the target distance estimation, a new target distance estimation method is obtained, an estimation result compared with an MUSIC algorithm is obtained under the condition of low signal-to-noise ratio, the frequency difference relation among frequency points is more fully utilized to estimate the distance direction, the azimuth direction can be estimated by adding the position difference relation among array elements under array element arrangement, and the effect of joint estimation is achieved.

Compared with the existing target distance estimation method of sparse connection map signals, the method adopts a full connection method when the adjacent matrix map signals are established, reduces the noise influence of the target distance estimation result, and improves the target distance estimation resolution.

Drawings

FIG. 1 is a diagram of a relationship between radar array elements and echo signals;

FIG. 2 is a signal diagram of a radar frequency point array diagram;

FIG. 3 is a schematic flow chart of the method of the present invention;

FIG. 4 is a diagram illustrating a multi-target original distance;

fig. 5 is a diagram illustrating a multi-target distance estimation result.

Detailed Description

The following further describes the embodiments of the present invention with reference to the drawings, but the present invention is not limited thereto.

Example (b):

the relation between the radar array and the target echo signal is, as shown in fig. 1, composed of a single radar transceiver unit and the target echo signal, where a single radar transmits and receives single-frequency signals of M frequency points to synthesize a broadband single-frequency signal, where targets at different distances may generate different echo delays.

Fig. 2 shows a radar frequency array connection diagram model for constructing a diagram signal model in a distance estimation algorithm unit, wherein M array elements are single-frequency signals of a radar, all array element frequency points are connected two by two respectively, and values on the edges are phase delays caused by the frequency difference between two array elements multiplied by an estimation distance:where n deltaf is the difference in frequency between the two array elements,the delay for the two-way path of the signal.

Fig. 3 shows the flow of the method of the present invention, a target distance estimation method based on graph signal processing, comprising the following steps:

(1) radar generation f_iStepped frequency signalWhere I is 1,2 … I, I is the number of frequency points, f_i＝f_c+ i · Δ f simultaneous elements transmit: i is the frequency point number, f_cAs a single frequency baseband signal, Δ f is a fixed frequency increment, which the radar transmits to the target.

(2) After the target is reflected, the receiving antenna receives the reflected echo signal of the target, and the reflected echo signal is collected by the data acquisition card, and the target echo signal can be expressed as:

wherein delta_mM is 1,2 … M for the scattering coefficient of each target, wherein M is the number of targets, noise (t-tau) represents additive noise after time delay, and tau represents echo phase difference caused by different distances in multiple targetsc represents the speed of light, R_iRepresents the distance of the mth target;

(3) arranging the phase information of different frequencies of the received target echo signals into a matrix to obtain an adjacent matrix A_s：

Wherein Δ f_i,jThe step frequency difference of the array element of the ith frequency point and the array element of the jth frequency point is represented;

(4) the adjacency matrix A can be reversely solved according to the orthogonality of echo signals and noise subspaces_sExpression (c): a. the_sx is x to obtain A_sElements of each row of the diagram signal

(5) According to the theorem of feature decomposition, the adjacent matrix A_sPerforming subspace decomposition to obtain a graph Fourier operator

(6) Echo signal S of the pair of image Fourier operators_m(t) performing a Fourier transform of the image to obtain a Fourier form of the image of the echo signal

(7) Method function F for estimating target distance by minimizing map signal_GSP(R), removing M +1 minimum values, and taking the reciprocal of the two norms to obtain a final distance direction estimation result:

an experimental scene is as follows:

the radar signal range target estimation system uses the target and radar structure diagram as shown in fig. 1, the two targets are at 9750m and 10250m respectively, and the radar snapshot time is 128. Radar signal carrier frequency f_c10GHz, frequency increment f_c100kHz, 10 single-frequency signals.

Imaging area range: the distance direction is 9500m to 10500m, a 100 multiplied by 1 search area is divided at equal intervals in the area, and the distance length of stepping is 10 m. Now, 2 point targets are set at (9500,0), (10500,0), respectively, assuming that the target scattering coefficient is 1.

The experimental results are as follows:

fig. 5 shows a simulation result of radar target range estimation using the method of the present invention, where the simulation result accurately estimates range parameters of two targets and also accurately reconstructs relative scattering coefficients of the targets. Fig. 4 shows original position information of multiple targets, and it can be seen from fig. 5 that the target distance estimation method using map signals can effectively estimate distance information of multiple targets.