阅读说明：本技术 一种同频干扰抑制方法 (Same frequency interference suppression method ) 是由 李思博 李玉娟 侯晓迁 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种同频干扰抑制方法,包括以下步骤：S1、通过所用的阵列得到阵列的接收信号,计算数据的相关矩阵R；S2、求取接收信号；S3、采用LCMV空间滤波重新计算干扰附近波束形成参数,在干扰方向上形成零陷,而在其他方向上则采用常规波束形成方法保持全通；S4、利用常规波束形成和线性约束最小方差波束形成的权矢量对第k个快拍的接收信号进行加权处理以实现波束形成,达到干扰抑制的目的。本发明将常规波束形成和线性约束最小方差结合,既保证了除干扰抑制方位外其他方位信号的无失真输出,又对干扰方位达到抑制效果,且干扰方位处的零陷效果自然不突兀,不会过分凹陷。(The invention discloses a same frequency interference suppression method, which comprises the following steps: s1, obtaining the receiving signals of the array through the array, and calculating a correlation matrix R of the data; s2, obtaining a received signal; s3, recalculating beam forming parameters near interference by LCMV spatial filtering, forming nulls in the interference direction, and keeping full pass in other directions by adopting a conventional beam forming method; s4, using the weight vector formed by the conventional beam forming and the linear constraint minimum variance beam to carry out weighting processing on the received signal of the kth snapshot so as to realize the beam forming and achieve the purpose of interference suppression. The invention combines the conventional beam forming and the linear constraint minimum variance, thereby not only ensuring the undistorted output of other azimuth signals except the interference suppression azimuth, but also achieving the suppression effect on the interference azimuth, and the null trap effect at the interference azimuth is naturally unobtrusive and cannot be excessively depressed.)

1. A co-channel interference suppression method is characterized by comprising the following steps:

s1, obtaining the receiving signal of the array through the array, using the obtained receiving signal X (k), calculating the correlation matrix R of the data,

s2, obtaining an array flow pattern vector of the received signal, including the expected signal and the interference signal, and including the following steps:

s21, obtaining the array popular vector of the target signal,

wherein, tau_mFor each array element signal time delay, according to the array type, M is 1,2, … M, M is the number of array elements, theta₀Is the target signal bearing;

s22, obtaining array popular vector of interference signal,

wherein, theta_rIs the target signal bearing;

s23, the received signal may be expressed as:

X(k)＝X_s(k)+X_r(k)+n(k)＝a_ss(k)+a_gr(k)+n(k)，

wherein, M is array element number, s (k) is target signal, r (k) is interference signal, n (k) is noise signal, k represents fast beat number; a is_sAnd a_rArray prevalence vectors for the target signal and the interference signal, respectively;

s3, recalculating beam forming parameters near interference by LCMV spatial filtering, forming nulls in the interference direction, and keeping full pass in other directions by adopting a conventional beam forming method;

s4, using the weight vector formed by conventional beam forming and linear constrained minimum variance beam forming to weight the received signal of the kth snapshot to realize beam forming, so as to achieve the purpose of interference suppression, and finally outputting the result as y (t) ═ w_CBF(X_s(t)+n(t))+w_LCMVX_r(t)。

2. The co-channel interference suppressing method as claimed in claim 1, wherein the LCMV criterion in step S3 is that a specific constraint is satisfied and the power is minimized, i.e., min [ w ]^HRw]The constraints can be expressed as follows: w is a^Ha ═ F, where F is a constraint; the method specifically comprises the following steps:

s31, the received signal is first processed by conventional beam forming, the conventional beam forming device weight vector is expressed as w_CBFA is a general name of the array popular vector;

s32, LCMV null filtering is adopted at the interference signal position, the weighting coefficient is recalculated, and the beams form nulls near the interference position; its beamformer weight vector is represented as:

wherein the content of the first and second substances,

Technical Field

The invention belongs to the technical field of underwater acoustic processing, and particularly relates to a same frequency interference suppression method.

Background

The interference suppression technology is to suppress the signal in the interference direction, so that the final processing result only contains the relevant information of the target echo, thereby realizing the extraction of the weak signal. The co-channel interference is interference caused by the fact that the center frequency of an interference signal is the same as that of a target signal and the interference signal and the target signal are received simultaneously. The purpose of co-channel interference suppression is to solve the problem of co-channel interference from the ship-friend under the formation combat condition and eliminate the white screen phenomenon caused by strong interference. Because the signal frequencies of the co-channel interference are consistent, a common frequency domain filter cannot be adopted to suppress the co-channel interference, and therefore the suppression of the co-channel interference is realized by utilizing a beam forming method in combination with spatial filtering. The spatial filtering is realized by filtering signals received by the array in a digital mode and weighting the received signals of each array element of the array with a certain shape in a certain mode. The beam control is carried out by utilizing a spatial filtering method, so that the spatial interference can be effectively inhibited, and the aim of enhancing useful signals is fulfilled.

For spatial filtering, usually, an anti-interference effect is achieved by using MVDR beam forming, but in the active sonar detection process, in order to improve concealment and interception resistance, the length of a transmitted signal is limited, so that the snapshot problem of limited-length data is generated, the MVDR has higher requirements on the snapshot number, when the snapshot number is less, the beam main lobe response cannot meet the requirements, and a beam pattern can be distorted.

Conventional beamforming has limited interference suppression capability, and cannot achieve suppression especially for strong interference. The LCMV can form nulls at the interference, but when less sampling data is adopted, the eigenvalue difference of the covariance matrix is too large, the matrix inversion is unstable, the sidelobe is increased, the interference suppression capability is affected, and when the sampling data is too large, the calculation amount is too high.

Therefore, there is a need for a co-channel interference suppression method that achieves interference suppression without reducing other signal strengths.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a same frequency interference suppression method.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a same frequency interference suppression method, which comprises the following steps:

s1, obtaining the receiving signal of the array through the array, using the obtained receiving signal X (k), calculating the correlation matrix R of the data,

s2, obtaining an array flow pattern vector of the received signal, including the expected signal and the interference signal, and including the following steps:

s21, obtaining the array popular vector of the target signal,

wherein, tau_mFor each array element signal time delay, according to the array type, M is 1,2, … M, M is the number of array elements, theta₀Is the target signal bearing;

s22, obtaining array popular vector of interference signal,

wherein, theta_rIs the target signal bearing;

s23, the received signal may be expressed as:

X(k)＝X_s(k)+X_r(k)+n(k)＝a_ss(k)+a_gr(k)+n(k)，

wherein, M is array element number, s (k) is target signal, r (k) is interference signal, n (k) is noise signal, k represents fast beat number; a is_sAnd a_rArray prevalence vectors for the target signal and the interference signal, respectively;

s3, recalculating beam forming parameters near interference by LCMV spatial filtering, forming nulls in the interference direction, and keeping full pass in other directions by adopting a conventional beam forming method;

s4, using the weight vector formed by conventional beam forming and linear constrained minimum variance beam forming to weight the received signal of the kth snapshot to realize beam forming, so as to achieve the purpose of interference suppression, and finally outputting the result as y (t) ═ w_CBF(X_s(t)+n(t))+w_LCMVX_r(t)。

As a preferred technical solution of the present invention, the LCMV criterion in the step S3 means that a specific constraint condition is satisfied and the power is minimized, i.e., min [ w [ ]^HRw]The constraints can be expressed as follows: w is a^Ha ═ F, where F is a constraint; the method specifically comprises the following steps:

s31, the received signal is first processed by conventional beam forming, the conventional beam forming device weight vector is expressed as w_CBFA is a general name of the array popular vector;

s32, LCMV null filtering is adopted at the interference signal position, the weighting coefficient is recalculated, and the beams form nulls near the interference position; its beamformer weight vector is represented as:

wherein the content of the first and second substances,

f is a random number with mean (X (k))/max (X (k)). The interference direction can be inhibited without distortion output in other direction signals for removing interference, and the null effect of interference inhibition can not be highlighted by selecting a constraint condition according to the signal intensity.

The invention has the beneficial effects that: the invention combines Conventional Beam Forming (CBF) and Linear Constraint Minimum Variance (LCMV), thereby ensuring the undistorted output of other azimuth signals except the interference suppression azimuth, achieving the suppression effect on the interference azimuth, and having natural and unobtrusive null trap effect at the interference azimuth without excessive depression. The invention is not only applicable to linear arrays, but also applicable to co-frequency interference suppression of other arrays such as cylindrical arrays.

Drawings

FIG. 1 is a graph showing the results of treatment using only the CBF method and the LCMV method.

FIG. 2 is a schematic view showing the effect of combining CBF method and LCMV method according to the present invention.

Detailed Description

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

In order to achieve the object of the present invention, in one embodiment of the present invention, there is provided an intra-channel interference suppression method, including the steps of:

s1, obtaining the receiving signal of the array through the array, using the obtained receiving signal X (k), calculating the correlation matrix R of the data,

s2, obtaining an array flow pattern vector of the received signal, including the expected signal and the interference signal, and including the following steps:

s21, obtaining the array popular vector of the target signal,

wherein, tau_mFor each array element signal time delay, according to the array type, M is 1,2, … M, M is the number of array elements, theta₀Is the target signal bearing;

s22, obtaining array popular vector of interference signal,

wherein, theta_rIs the target signal bearing;

s23, the received signal may be expressed as:

X(k)＝X_s(k)+X_r(k)+n(k)＝a_ss(k)+a_gr(k)+n(k)，

wherein, M is array element number, s (k) is target signal, r (k) is interference signal, n (k) is noise signal, k represents fast beat number; a is_sAnd a_rRespectively target signal and interferenceAn array prevalence vector of signals;

s3, recalculating beam forming parameters near interference by LCMV spatial filtering, forming nulls in the interference direction, and keeping full pass in other directions by adopting a conventional beam forming method; the LCMV criterion refers to the satisfaction of certain constraints and minimizes the power, i.e., min [ w ]^HRw]The constraints can be expressed as follows: w is a^Ha ═ F, where F is a constraint; the method specifically comprises the following steps:

s31, the received signal is first processed by conventional beam forming, the conventional beam forming device weight vector is expressed as w_CBFA is a general name of the array popular vector;

s32, LCMV null filtering is adopted at the interference signal position, the weighting coefficient is recalculated, and the beams form nulls near the interference position; its beamformer weight vector is represented as:

wherein the content of the first and second substances,

f is a random number with mean (X (k))/max (X (k)), thus ensuring that signals in other directions without interference can be output without distortion and the interference directions are inhibited, and selecting constraint conditions according to the signal strength to ensure that the null effect of interference inhibition is not excessively prominent;

s4, using the weight vector formed by conventional beam forming and linear constrained minimum variance beam forming to weight the received signal of the kth snapshot to realize beam forming, so as to achieve the purpose of interference suppression, and finally outputting the result as y (t) ═ w_CBF(X_s(t)+n(t))+w_LCMVX_r(t)。

Fig. 1 shows the processing results of only using the CBF method and the LCMV method, and it can be seen from fig. 1 that the CBF method has no effect of suppressing the interference signal, and the LCMV can form a null at the interference position, but when less sampling data is used, the eigenvalue difference of the covariance matrix is too large, and the matrix inversion is unstable, which may cause the side lobe to be increased, thereby affecting the interference suppression capability.

Fig. 2 combines the CBF method and the LCMV method to form a deeper null at the interference position, thereby achieving a better interference suppression effect.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.