CN101726730A - Self-adaption anti-coherent interference technology based on characteristic component rejection - Google Patents

Abstract

The invention discloses a self-adaption anti-coherent interference technology based on characteristic component rejection. Firstly, characteristic decomposition is carried out on an antenna multichannel receiving data covariance matrix to judge the number of a big characteristic value; then, the characteristic vector corresponding to signals and coherent interference is searched in a characteristic vector group corresponding to the big characteristic value so as to subtract the characteristic vector from the covariance matrix; finally, diagonal loading is carried out on the covariance matrix removing signals and coherent interference components, and the loaded matrix is used for calculating a self-adaption weight, data is weighed, and specific steps are disclosed in the drawing. The method of the invention avoids cancellation of desired signals while inhibiting incoherent interference, does not have array aperture loss and does not need to master the direction priori information of coherent interference. The method only relates to characteristic decomposition and inversion operation but does not relate to high-order cumulant operation, so that the method has simple steps and small calculation amount; the device is simple and has low cost. In addition, the method of the invention receives and utilizes the coherent interference as a wanted signal so as to improve the receiving gain of a target signal, thus owning better receiving performance. The method of the invention can be realized only by downloading a program to a general signal processing board, is easy to popularize and only needs to programme on a programmable signal processing board; thus, the system is convenient to upgrade while the system structure is not changed. The method of the invention can be widely applied to a system with various kinds of receiving channel structures and has popularization and application value.

Description

Self-adaption anti-coherent interference technology based on characteristic component rejection

Technical field

The present invention relates to a kind of adaptive coherent interference mitigation technology in the signal Processing field, be applicable to signal processing system with a plurality of spatial domains passage, as the phased-array radar signal processing system with adopt the communication system etc. of array antenna, can be used for incoherent interference and coherent interference and have target detection under the environment simultaneously, realize to the inhibition of incoherent interference with to the utilization of coherent interference.

Background technology

In adaptive array signal is handled, often there is coherent interference, as multipath reflection, intelligence interference etc., this moment, conventional adaptive beam formation method can cause that wanted signal disappears mutually, caused wave beam to form the serious decline of performance.Therefore, how to suppress coherent interference effectively is the interior difficult point of correlative technology field always.Under this background, often adopt Search Space Smoothing to handle, promptly utilize the space of subarray to slide and reduce the coherence, carry out interference cancellation then, but this technology is a cost to reduce effective array aperture, and only is applicable in the uniform line-array class array.This has all seriously limited performance and application that adaptive beam forms.

In order to improve the shortcoming of above-mentioned background technology, need incoherent interference of identification and coherent interference, to cause that coherent interference and incoherent interference separation that expectation disappears mutually come out, this has two class methods to utilize: the one, seek the difference of undesired signal in unconventional parameter field, as adopting optimal blind beam-forming technology based on semi-invariant; The 2nd, the direction of arrival information of extraction wanted signal and coherent interference is distinguished it from the spatial domain, as is split phase inversion de-correlation technique, multiple constraint Minimum Variance method and householder transformation Minimum Variance method etc.Yet, before a kind of method can only be used for that wanted signal and coherent interference belong to skewed distribution and other disturbs and noise belongs to the special occasions of normal distribution, and this technology is owing to will carry out the Higher Order Cumulants estimation, therefore also have the shortcoming that required hits is many, operand is very big, using with engineering practice still has a segment distance; A kind of method in back needs to be grasped the direction of arrival priori of wanted signal and coherent interference, under most of situation, these prioris are impossible known, must be estimated, and coherent signal is carried out the direction of arrival estimation itself is exactly a focus, difficult point problem, all the more so under complex environment.Therefore, a kind of can simple, adaptive differentiation coherent interference and the technology of incoherent interference become the key of application self-adapting beam-forming technology under the coherent interference environment.

Summary of the invention

The objective of the invention is to overcome the deficiency in the above-mentioned background technology, do not change under the situation of the existing channel architecture of service system, overcome the expectation phenomenon that disappears mutually, realize the reservation of signal and the inhibition of incoherent interference.

In order to realize above-mentioned goal of the invention, the invention provides a kind of self-adaption anti-coherent interference technology based on characteristic component rejection, comprise the steps:

(1) utilize the individual receiving cable of the intrinsic M of system (M＞1), M * N dimension is received data X send into signal processing system, N is a hits;

(2) signal processing system is carried out covariance matrix to the channel data that receives, thereby obtains the covariance matrix R of multi channel signals:

$R=\frac{1}{N}{\mathrm{XX}}^H$

(3) covariance matrix R is carried out feature decomposition, the eigenvalue of being arranged by size ₁〉=λ ₂〉=... 〉=λ _MWith character pair set of vectors u ₁, u ₂..., u _M

(4) judge big eigenwert number P according to the information theory criterion, P is the signal number that estimation obtains, and comprises and disturbing and target;

(5) in big eigenwert characteristic of correspondence set of vectors, find out expectation and coherent interference character pair vector u according to following formula _l:

$u_l=\arg \underset{\underset{1\≤m\≤P}{u_m}}{\max }{\left|u_m^{H}a\left({\mathrm{\θ}}_0\right)\right|}^2$

A (θ in the formula ₀) being expectation signal guide vector, it is known;

(6) in covariance matrix R, deduct expectation and coherent interference character pair set of vectors correlation matrix, obtain R ':

$R^{\′}=R-{\mathrm{\λ}}_l{u}_l{u}_l^H$

(7) R ' is carried out an amount of diagonal angle and loads,

$\hat{R}=R^{\′}+\mathrm{LI}$

L is a heap(ed) capacity in the formula, rule of thumb determines;

(8) obtain adaptive weight:

$w=\underset{w^{H}a\left({\mathrm{\θ}}_0\right)=1}{\arg \min }{w}^H\hat{R}w={\mathrm{\μ}}^{\′}{\hat{R}}^{-1}a\left({\mathrm{\θ}}_0\right)$

μ ' in the formula=1/[a ^H(θ ₀) (R '+LI) ^-1A (θ ₀)], be a constant, to the multi-channel data weighting, the result send subsequent treatment with the adaptive weight that obtains.

Wherein, R ' also can a reservation be arranged in u in the step (6) _lEigenvector correlation matrix before: $R^{\′}=\underset{i=1}{\overset{l-1}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{u}_i{u}_i^H.$

The calculating of heap(ed) capacity also can be adopted by the little eigenwert mean value of R and calculate in the step (7): $L=\underset{i=P+1}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\λ}}_i/(M-P).$

The invention has the advantages that:

(1) the present invention has rejected the contribution of wanted signal and coherent interference in the covariance matrix adaptively, when suppressing uncorrelated interference, has avoided disappearing mutually of wanted signal, and has not had the array aperture loss.

(2) the present invention need not grasp the direction prior imformation of coherent interference, has avoided the coherent interference direction is estimated and error effect that step is simple.

(3) processing procedure of the present invention only relates to feature decomposition and inversion operation, does not relate to the Higher Order Cumulants computing, and calculated amount is little.Equipment is simple, and is with low cost.

(4) the present invention is received utilization to coherent interference as useful signal, has improved the gain that echo signal is received.Therefore has better receptivity.

(5) the present invention only need download to program on the universal signal disposable plates and can realize, therefore is easy to promote, and only need programmes on the general programmable signal-processing board, so when not changing system architecture, system upgrade is convenient.

Description of drawings

Fig. 1 is the structured flowchart of embodiments of the invention.

With reference to Fig. 1, embodiments of the invention are removed unit 6, diagonal angle loading unit 7 and weights calculating by antenna multichannel receiving element 1, covariance matrix unit 2, characteristic value decomposition unit 3, big eigenwert judging unit 4, signal and coherent interference eigenvector judging unit 5, coherent interference and signal and are formed with weighted units 8.Realization that above-mentioned covariance estimation, feature decomposition, eigenwert judgement greatly, signal and the judgement of coherent interference eigenvector, coherent interference and signal are removed, the diagonal angle is airborne, weights calculate and weighting all can be programmed on the general programmable signal-processing board.

Embodiment

It is as follows to implement principle of the present invention:

Often much larger than wanted signal and these characteristics of coherent interference, the present invention proposes a kind of new self-adaption anti-coherent interference technology based on characteristic component rejection at incoherent interference in the actual environment.This technology estimates the pairing eigenvector of composite signal of wanted signal and coherent interference earlier, abandons in covariance matrix after the contribution of this part signal, carries out self-adaptation again and asks power and offset processing.The reasonable part of this way is, at signal (comprising wanted signal and undesired signal) when there is difference in power, exist one-to-one relationship between data covariance matrix big eigenwert character pair vector and the signal guide vector, this moment, eigenvector can reflect the respective signal steering vector respectively, and was not subjected to the influence of other signal guide vectors.

Supposing the system has M hyperchannel, and hits is N, M=8 among the embodiment, N=100.The detailed step of whole invention once is described below in conjunction with drawings and Examples:

(1) by the single unit 1 of receiving of antenna multichannel the digital signal data that receives is stored in the system, this part is identical with original system to the accuracy requirement of the size of storer, sampling.

(2) covariance matrix unit 2 N sampling that receiving element 1 is sent here carried out covariance and estimated that formula is as follows:

R＝XX ^H/N

X is the data matrix that receives in the formula, and its dimension is M * N, and R is a data covariance matrix.

(3) the data covariance matrix R that sends here of 3 pairs of unit 2, characteristic value decomposition unit carries out feature decomposition, the eigenvalue of being arranged by size ₁λ ₂λ _MWith character pair set of vectors u ₁u ₂... u _M

(4) eigenvalue of utilizing unit 3 to send here ₁λ ₂λ _M, judging characteristic value number P+1.This can select to utilize AIC, MDL and HQ information theory criterion to judge big eigenwert number according to eigenwert relative size and hits, adopts the HQ criterion to carry out the judgement of big eigenwert number among the embodiment.

(5) big eigenwert characteristic of correspondence set of vectors u is calculated in big eigenwert number P+1 that draws according to big eigenwert judging unit 4 ₁u ₂... u _P+1With wanted signal steering vector a (θ ₀) inner product, select signal and coherent interference characteristic of correspondence vector u according to size _l:

$u_l=\arg \underset{\underset{1\≤m\≤P+1}{u_m}}{\max }{\left|u_m^{H}a\left({\mathrm{\θ}}_0\right)\right|}^2$

(6) the eigenvector u that selects in the computing unit 5 _lApposition, multiply by character pair value λ _l, from covariance matrix R, deduct, do not contained the covariance matrix R ' of signal and coherent interference:

$R^{\′}=R-{\mathrm{\λ}}_l{u}_l{u}_l^H$

(7) the covariance matrix R ' that unit 6 is provided carries out the diagonal angle loading:

$\hat{R}=R^{\′}+\mathrm{LI}$

I is a unit matrix in the formula, and L is a heap(ed) capacity.It mainly is that R ' is directly inverted matrix morbid state can occur, and can avoid this problem after loading because R ' handles the contraction of R that the diagonal angle loads.Therefore, heap(ed) capacity L can calculate according to matrix R eigenwert:

$L=\underset{i=P+2}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\λ}}_i/(M-P-1)$

(8) utilize covariance matrix R ' calculating weights after the loading of unit 7 output:

$w=\underset{w^{H}a\left({\mathrm{\θ}}_0\right)=1}{\arg \min }{w}^H\hat{R}w={\mathrm{\μ}}^{\′}{\hat{R}}^{-1}a\left({\mathrm{\θ}}_0\right)$

μ ' in the formula=1/[a ^H(θ ₀) (R '+LI) ^-1A (θ ₀)], be a constant.Utilize this weights weight data, obtain exporting y:

y＝w ^HX

Send subsequent treatment with y at last.

Though described embodiments of the present invention in conjunction with the accompanying drawings, those of ordinary skills can make various distortion or modification within the scope of the appended claims.

Claims (3)

1. self-adaption anti-coherent interference technology based on characteristic component rejection comprises following technical step:

(1) utilize the individual receiving cable of the intrinsic M of system (M＞1), M * N dimension is received data X send into signal processing system, N is a hits;

(2) signal processing system is carried out covariance matrix to the channel data that receives, thereby obtains the covariance matrix R of multi channel signals:

$R=\frac{1}{N}{\mathrm{XX}}^H$

(3) covariance matrix R is carried out feature decomposition, the eigenvalue of being arranged by size ₁〉=λ ₂〉=... 〉=λ _MWith character pair set of vectors u ₁, u ₂..., u _M

(4) judge big eigenwert number P according to the information theory criterion, P is the signal number that estimation obtains, and comprises and disturbing and target;

(5) in big eigenwert characteristic of correspondence set of vectors, find out expectation and coherent interference character pair vector u according to following formula _l:

$u_l=\arg \underset{1\≤m\≤P}{\underset{u_m}{\max }}{\left|u_m^{H}a\left({\mathrm{\θ}}_0\right)\right|}^2$

A (θ in the formula ₀) being expectation signal guide vector, it is known;

(6) in covariance matrix R, deduct expectation and coherent interference character pair set of vectors correlation matrix, obtain R ':

$R^{\′}=R-{\mathrm{\λ}}_l{u}_l{u}_l^H$

(7) R ' is carried out an amount of diagonal angle and loads,

$\hat{R}=R^{\′}+\mathrm{LI}$

L is a heap(ed) capacity in the formula, rule of thumb determines;

(8) obtain adaptive weight:

$w=\underset{w^{H}a\left({\mathrm{\θ}}_0\right)=1}{\arg \min }{w}^H\hat{R}w={\mathrm{\μ}}^{\′}{\hat{R}}^{-1}a\left({\mathrm{\θ}}_0\right)$

μ ' in the formula=1/[a ^H(θ ₀) (R '+LI) ^-1A (θ ₀)], be a constant, to the multi-channel data weighting, the result send subsequent treatment with the adaptive weight that obtains.

2. the self-adaption anti-coherent interference technology based on characteristic component rejection according to claim 1 is characterized in that, when deducting expectation with coherent interference character pair vector in covariance matrix R, R ' also can a reservation be arranged in u _lEigenvector correlation matrix before:

$R^{\′}=\underset{i=1}{\overset{l-1}{\mathrm{\Σ}}}{\mathrm{\λ}}_i{u}_i{u}_i^H$

3. the self-adaption anti-coherent interference technology based on characteristic component rejection according to claim 1 is characterized in that, the calculating of heap(ed) capacity also can be adopted by the little eigenwert mean value of R and calculate in the R ' diagonal angle loading procedure:

$L=\underset{i=P+2}{\overset{M}{\mathrm{\Σ}}}{\mathrm{\λ}}_i/(M-P-1)$

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