CN101388656A - Polarized filtering method based on inclined projection without needs of interference polarization parameter - Google Patents

Abstract

The invention relates to a polarization filtering method which is based on oblique projection and does not need to disturb polarization parameters, wherein the method comprises: determining the polarization parameters of a target signal, estimating the noise power, building a polaron space of the target signal by the polarization parameters of the target signal, calculating an oblique projector and a filter operator which are corresponding to the polaron space of the target signal and the noise power, accurately distilling the target signal by the filter operator, and filtering an interference signal. The polarization filtering method can carry out polarization filtering under the conditions of a cartesian coordinate system and an elliptic coordinate system, and can accurately distill the target signal.

Description

Polarized filtering method based on inclined projection without needs of interference polarization parameter

Technical field

The present invention relates to a kind of signal processing technology, particularly utilize shadow casting technique and polarized signal treatment technology to implement the method for polarization filtering.

Background technology

As the supplementary form of time-domain signal processing, frequency-region signal processing and spatial domain signal processing, the polarizing field signal processing technology more and more is subjected to people's attention, has obtained using more widely in radar and communication system.In Anti-Jamming Technique, the anti-interference anti-interference and jamproof distinguishing feature in spatial domain of the frequency domain of being different from that has polarizes, it is to utilize interference signal and echo signal to suppress to disturb and extract signal, the restriction of factors such as therefore interference-free frequency and space incident direction in the difference of polarized state.As long as there is difference in the polarized state of interference and target, even both other characteristics are all identical, also can it be separated by Polarization Filtering Technology, perhaps interference is suppressed.

Though the conventional polar filtering method can suppress to disturb preferably, but because it is to be based upon on the basis of rectangular projection, therefore when the polarized state of target and interference is nonopiate, can the amplitude and the phase place of echo signal be exerted an influence when suppressing to disturb, it is very difficult that expectation is eliminated these influences by direct compensation.

The zero phase-shift polarization filtering is transformed into 90 degree by linear polarization vector conversion (LPVT) with the polarizing angle of echo signal, carry out polarization filtering then, and then adopt amplitude/phase compensation (A/PCD) to recover the amplitude and the phase information of echo signal, realized accurate reduction to echo signal.This method is more influential algorithm in present polarized filtering method, also is a kind of algorithm of comparative maturity.Yet, polarizing angle identical when the polarizing angle of echo signal and interference differs under difference or the ellipticity angle is identical, the azimuth the is different condition, and the zero phase-shift polarization filtering has also suppressed echo signal when suppressing to disturb, can't finish the purpose of polarization filtering.

Conventional polar filtering and zero phase-shift polarization filtering need simultaneously the polarized state of echo signal and interference to be estimated, exist the high problem of system complexity, simultaneously, interference signal polarization parameter estimated bias can limit the performance of polarization filtering, therefore, further improve and the theory of development polarization filtering and the method for designing of polarization filtering, finding a kind of simple, amount of calculation method little, that be easy to realize is very to be necessary.

Summary of the invention

The invention provides a kind of polarized filtering method based on oblique projection, this method does not need to estimate that the polarized state disturbed also can suppress simultaneously the amplitude and the phase place of echo signal are not exerted an influence to interference, simply, amount of calculation is little and be easy to realize, solve exist in the prior art when suppressing to disturb, also to target signal generating influence or system complex degree height, technical problem that amount of calculation is big.

The method that the present invention solves the problems of the technologies described above is: a kind of polarized filtering method based on inclined projection without needs of interference polarization parameter comprises following steps:

A. determine the polarization parameter of echo signal;

B. estimate the power of noise, set up echo signal polaron space by the polarization parameter of echo signal in the steps A;

C. pairing oblique projection operator of echo signal polaron space of setting up among the calculation procedure B and noise power and filter operator;

D. the filter operator that is obtained by step C accurately extracts echo signal, filtering interference signals.

Under the situation that adopts cartesian coordinate system, the parameter value of echo signal is that polarizing angle and polarizing angle differ.Under the situation that adopts elliptical coordinate system, the parameter value of echo signal is ellipticity angle and azimuth.

The power of noise is the variance of white Gaussian noise among the described step B, and the pseudoinverse that target adds the correlation matrix of interference is:

R＝E{y(t)y ^H(t)}＝E{(s(t)+i(t)+n)(s(t)+i(t)+n) ^H}

＝E{(x(t)+n)(x(t)+n) ^H}＝E{x(t)x ^H(t)}+E{nn ^H}

＝R _xx+σ ²I

$R_{\mathrm{xx}}^{+}={(R-{\mathrm{\σ}}^{2}I)}^{+}.$

In the described steps A, the polarizing angle of echo signal is ε _s, polarizing angle differs and is δ _s, described echo signal polaron space is

$S={[\cos {\mathrm{\ϵ}}_S,\sin {\mathrm{\ϵ}}_S{e}^{j{\mathrm{\δ}}_S}]}^T.$

In the described steps A, the ellipticity angle of echo signal is τ _s, the azimuth is

, described echo signal polaron space is

Among the described step C, the pairing oblique projection operator in echo signal polaron space is

$E_{\mathrm{SI}}=S{\left(S^H{R}_{\mathrm{xx}}^{+}S\right)}^{-1}{S}^H{R}_{\mathrm{xx}}^{+}.$

Among the described step C, the pairing filter operator in echo signal polaron space is

$Q={E_{\mathrm{SI}}}^{T}P={E_{\mathrm{SI}}}^T\left[\begin{array}{c}\cos {\mathrm{\ϵ}}_s\\ \sin {\mathrm{\ϵ}}_s\end{array}\right]$ Or $Q={E_{\mathrm{SI}}}^{T}P={E_{\mathrm{SI}}}^T\frac{1}{\sqrt{2}}\left[\begin{array}{c}\sqrt{1+\sin \left(2{\mathrm{\τ}}_s\right)}\\ \sqrt{1-\sin \left(2{\mathrm{\τ}}_s\right)}\end{array}\right];$

Among the described step D, echo signal is

s(t)＝y(t) ^TQ。

Under the situation that adopts cartesian coordinate system, among the step C, received signal is the 2D signal with horizontal component and vertical component, become the one-dimensional signal that has only one-component by signal after the polarization filtering, through oblique projection operator operation back signal still is a 2D signal with horizontal component and vertical component, need through a projection this signal to be become the one-dimensional signal that has only one-component again, this projection operator is

P＝[cosε _s，sinε _s] ^T。

Under the situation that adopts elliptical coordinate system, among the step C, received signal is the 2D signal with horizontal component and vertical component, become the one-dimensional signal that has only one-component by signal after the polarization filtering, through oblique projection operator operation back signal still is a 2D signal with horizontal component and vertical component, need through a projection this signal to be become the one-dimensional signal that has only one-component again, this projection operator is

$P=\frac{1}{\sqrt{2}}{[\sqrt{1+\sin \left(2{\mathrm{\τ}}_s\right)},\sqrt{1-\sin \left(2{\mathrm{\τ}}_s\right)}]}^T.$

Compare with existing polarized filtering method, the present invention has the following advantages: 1, do not need to estimate the polarized state disturbed, as long as the polarized state of estimating target signal; 2, do not need to carry out to received signal the polarization vector conversion; 3, do not need to compensate the amplitude and the phase characteristic (see figure 2) that can keep echo signal; 4, identical, the polarizing angle of the polarizing angle in echo signal and interference differs under difference or the ellipticity angle is identical, the azimuth the is different condition and also can carry out polarization filtering, realize separating of echo signal and interference easily, perhaps the inhibition of Gan Raoing (is seen Fig. 3, wherein amplitude is 1, centre frequency is that the sinusoidal signal of 1GHz is an echo signal, two amplitudes are 2, and centre frequency also is that the different sinusoidal signal of 1GHz but initial phase is for disturbing signal to noise ratio 10dB condition).Realize the accurate recovery of echo signal, and had little, simple, the practical advantage of amount of calculation.

Description of drawings:

Fig. 1 is a steps flow chart of the present invention.

Fig. 2 the present invention is based on the comparison to the echo signal phase effect of the polarized filtering method of inclined projection without needs of interference polarization parameter and conventional polar filtering method.

Fig. 3 is the comparison that the present invention is based on the polarized filtering method and the conventional polar filtering method filter effect of inclined projection without needs of interference polarization parameter.

Embodiment:

In conjunction with top description of drawings specific embodiments of the present invention.

The present invention can implement under cartesian coordinate system and two kinds of coordinate system conditions of elliptical coordinate system, and the embodiment of method disclosed by the invention comprises four steps as shown in Figure 1.

When the present invention described as if the employing cartesian coordinate system, this polarized state is expressed as polarizing angle and polarizing angle differs, and in order to realize the foregoing invention purpose, the step of the present invention in the enlightening cartesian coordinate system is:

First step: determine that the polarizing angle of echo signal and polarizing angle differ;

Second step: estimate the power of noise, promptly estimate the variances sigma of white Gaussian noise ²The setting received signal is y (t), and echo signal and interference are respectively s (t), i (t), and n is an additive white Gaussian noise, calculates the pseudoinverse that target adds the correlation matrix of interference thus

R＝E{y(t)y ^H(t)}＝E{(s(t)+i(t)+n)(s(t)+i(t)+n) ^H}

＝E{(x(t)+n)(x(t)+n) ^H}＝E{x(t)x ^H(t)}+E{nn ^H}

＝R _xx+σ ²I

$R_{\mathrm{xx}}^{+}={(R-{\mathrm{\σ}}^{2}I)}^{+};$

The conjugate transpose of H representing matrix wherein, the pseudoinverse of+representing matrix; R represents the autocorrelation matrix of received signal in the above-mentioned formula, and I is a unit matrix;

By the echo signal polarization parameter that draws in the first step, set up echo signal polaron space S

$S={[\cos {\mathrm{\ϵ}}_s,\sin {\mathrm{\ϵ}}_s{e}^{j{\mathrm{\δ}}_s}]}^T;$

T is transpose of a matrix, ε in the above-mentioned formula _sBe the polarizing angle of the echo signal determined, δ _sFor the echo signal polarizing angle of determining differs;

Third step: at first calculate by the pairing oblique projection operator in echo signal polaron space that obtains in second step, computing formula is as follows:

$E_{\mathrm{SI}}=S{\left(S^H{R}_{\mathrm{xx}}^{+}S\right)}^{-1}{S}^H{R}_{\mathrm{xx}}^{+};$

Obtain filter operator Q by following computing based on the polarized filtering method of oblique projection:

$Q={E_{\mathrm{SI}}}^{T}P={E_{\mathrm{SI}}}^T\left[\begin{array}{c}\cos {\mathrm{\ϵ}}_s\\ \sin {\mathrm{\ϵ}}_s\end{array}\right];$

The 4th step: set received signal and be expressed as y (t), extract echo signal s (t) by following formula:

s(t)＝y(t) ^TQ；

When the present invention described as if the employing elliptical coordinate system, this polarized state was expressed as the ellipticity angle and the azimuth of polarization, and the embodiment under the elliptical coordinate system condition is:

First step: ellipticity angle and the azimuth of determining echo signal;

Second step: estimate the power of noise, promptly estimate the variances sigma of white Gaussian noise ²The setting received signal is y (t), and echo signal and interference are respectively s (t), i (t), and n is an additive white Gaussian noise, calculates the pseudoinverse that target adds the correlation matrix of interference thus

R＝E{y(t)y ^H(t)}＝E{(s(t)+i(t)+n)(s(t)+i(t)+n) ^H}

＝E{(x(t)+n)(x(t)+n) ^H}＝E{x(t)x ^H(t)}+E{nn ^H}

＝R _xx+σ ²I

$R_{\mathrm{xx}}^{+}={(R-{\mathrm{\σ}}^{2}I)}^{+};$

The conjugate transpose of H representing matrix wherein, the pseudoinverse of+representing matrix; R represents the autocorrelation matrix of received signal in the above-mentioned formula, and I is a unit matrix.

By the echo signal polarization parameter that draws in the first step, set up echo signal polaron space S

τ in the above-mentioned formula _sBe the ellipticity angle of the echo signal determined,

Be the echo signal azimuth of determining.

Third step: at first calculate by the pairing oblique projection operator in echo signal polaron space that obtains in second step, computing formula is as follows:

$E_{\mathrm{SI}}=S{\left(S^H{R}_{\mathrm{xx}}^{+}S\right)}^{-1}{S}^H{R}_{\mathrm{xx}}^{+}$

Obtain filter operator Q by following computing based on the polarized filtering method of oblique projection:

$Q={E_{\mathrm{SI}}}^{T}P={E_{\mathrm{SI}}}^T\frac{1}{\sqrt{2}}\left[\begin{array}{c}\sqrt{1+\sin \left(2{\mathrm{\τ}}_s\right)}\\ \sqrt{1-\sin \left(2{\mathrm{\τ}}_s\right)}\end{array}\right].$

The 4th step: set received signal and be expressed as y (t), extract echo signal s (t) by following formula:

s(t)＝y(t) ^TQ。

Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, can not assert that concrete enforcement of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.

Claims (9)

1. polarized filtering method based on inclined projection without needs of interference polarization parameter, it is characterized in that: the method includes the steps of:

A. determine the polarization parameter of echo signal;

B. estimate the power of noise, set up echo signal polaron space by the polarization parameter of echo signal in the steps A;

C. pairing oblique projection operator of echo signal polaron space of setting up among the calculation procedure B and noise power and filter operator;

D. the filter operator that is obtained by step C accurately extracts echo signal, filtering interference signals.

2. polarized filtering method according to claim 1 is characterized in that: in the described steps A, under the situation that adopts cartesian coordinate system, the parameter value of echo signal is that polarizing angle and polarizing angle differ.

3. polarized filtering method according to claim 1 is characterized in that: in the described steps A, under the situation that adopts elliptical coordinate system, the parameter value of echo signal is ellipticity angle and azimuth.

4. according to claim 2 or 3 described polarized filtering methods, it is characterized in that: the power of noise is the variance of white Gaussian noise among the described step B, and the pseudoinverse that target adds the correlation matrix of interference is:

R＝E{y(t)y ^H(t)}＝E{(s(t)+i(t)+n)(s(t)+i(t)+n) ^H}

＝E{(x(t)+n)(x(t)+n) ^H}＝E{x(t)x ^H(t)}+E{nn ^H}

＝R _xx+σ ²I

$R_{\mathrm{xx}}^{+}={(R-{\mathrm{\σ}}^{2}I)}^{+}.$

5. polarized filtering method according to claim 2 is characterized in that: in the described steps A, the polarizing angle of echo signal is ε _s, polarizing angle differs and is δ _s, described echo signal polaron space is

$S={[\cos {\mathrm{\ϵ}}_s,\sin {\mathrm{\ϵ}}_s{e}^{j{\mathrm{\δ}}_s}]}^T.$

6. polarized filtering method according to claim 3 is characterized in that: in the described steps A, the ellipticity angle of echo signal is τ _s, the azimuth is

Described echo signal polaron space is

7. according to claim 5 or 6 described polarized filtering methods, it is characterized in that: among the described step C, the pairing oblique projection operator in echo signal polaron space is

$E_{\mathrm{SI}}=S{\left(S^H{R}_{\mathrm{xx}}^{+}S\right)}^{-1}{S}^H{R}_{\mathrm{xx}}^{+}.$

8. polarized filtering method according to claim 7 is characterized in that: among the described step C, the pairing filter operator in echo signal polaron space is

Q＝E _SI ^T $P={E_{\mathrm{SI}}}^T\left[\begin{array}{c}\cos {\mathrm{\ϵ}}_s\\ \sin {\mathrm{\ϵ}}_s\end{array}\right]$ Or Q=ESI ^T $P={E_{\mathrm{SI}}}^T\frac{1}{\sqrt{2}}\left[\begin{array}{c}\sqrt{1+\sin \left(2{\mathrm{\τ}}_s\right)}\\ \sqrt{1-\sin \left(2{\mathrm{\τ}}_s\right)}\end{array}\right];$

Among the described step D, echo signal is

s(t)＝y(t) ^TQ。

9. polarized filtering method according to claim 2, it is characterized in that: among the step C, received signal is the 2D signal with horizontal component and vertical component, become the one-dimensional signal that has only one-component by signal after the polarization filtering, through oblique projection operator operation back signal still is a 2D signal with horizontal component and vertical component, need through a projection this signal to be become the one-dimensional signal that has only one-component again, this projection operator is

P＝[cosε _s，sinε _s] ^T。

10. polarized filtering method according to claim 3, it is characterized in that: it utilizes in the third step that elliptical coordinate system is described: received signal is the 2D signal with horizontal component and vertical component, become the one-dimensional signal that has only one-component by signal after the polarization filtering, through oblique projection operator operation back signal still is a 2D signal with horizontal component and vertical component, need through a projection this signal to be become the one-dimensional signal that has only one-component again, this projection operator is

$P=\frac{1}{\sqrt{2}}{[\sqrt{1+\sin \left(2{\mathrm{\τ}}_s\right)},\sqrt{1-\sin \left(2{\mathrm{\τ}}_s\right)}]}^T.$

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