CN103336269A - Cognitive waveform optimization processing method used for multi-transmission GMTI radar system - Google Patents

Abstract

The invention discloses a cognitive waveform optimization processing method used for a multi-transmission GMTI (Ground Moving Target Indication) radar system. The method comprises the steps that a distance unit to-be-detected is set as a desired signal; information of a distance unit adjacent to the distance unit to-be-detected is regarded as an interference signal; based on a weight of an initial pulse pressure filter, an initial time domain response output result is obtained; according to prior information, artificial interference is added to a sidelobe area of the initial time domain response output result; a weight of the pulse pressure filter next time is optimally designed by controlling power of the artificial interference; a time domain response diagram inversely matched with an environment is obtained after repeated iterations, that is a low sidelobe is formed in a place with stronger clutter interference; and a higher sidelobe is formed in a place with weaker or no clutter interference. The filter designed by the method takes a template designed according to environment prior knowledge as a reference, the low sidelobe is designed in a strong clutter area, and the high sidelobe is designed in a weak or no clutter area, so that the filter has the adaptive capability, and can inhibit clutter better.

Description

A kind of for multiple cognitive waveform optimization disposal route of penetrating the GMTI radar system

Technical field

The invention belongs to the Radar Technology field, relate to a kind of based on the adaptive pulse compression filter method for designing of priori environment knowledge in this field, the present invention can be applied to random waveform and the contrary process of pulse-compression of mating of any environment, also can be applicable to separate under the multiple ejected wave shape situation pulse compression information of each waveform.Wave filter is with reference to the stencil design of the contrary coupling of environment, thus therefore better clutter reduction improve the detection performance of target.

Background technology

Cognitive system is by the study for target and environment, the information feedback that to extract from echo is to transmitter, form closed-loop system, transmitter conforms it and reaches the purpose of improving radar performance according to new the transmitting of environmental information adaptive optimization design then.Environmental information is mainly derived from: the echo after the radar emission signal reflects in space environment, the knowledge of the enemy radar reconnaissance equipment that obtains based on our relevant device and the environment distributed intelligence that other sensors obtain.In multiple cognitive radar system of penetrating GMTI, suppressing could easier detection ground moving object from the echo of static target or ground clutter.Multichannel clutter rejection is relevant with the consistance of passage.Therefore, in multiple cognitive radar system of penetrating GMTI, not only require the contrary coupling of each passage (pulse compression result) and environmental information, also require to have high related coefficient between the isolated a plurality of passages of pulse pressure.

The tradition pulse compression filter does not have adaptive ability to environment, and the target detection ability tends to descend under the complex electromagnetic environment background.Existing least square method can the equally distributed secondary lobe of optimal design, but because energy constant, equally distributed sidelobe level has theoretical ultimate value, therefore not necessarily can access ideal results.And actual environment information is often fast changing and be not equally distributed, with the time the complicate adaptive Waveform Design of electromagnetic environment and handle more can realistic demand.

Summary of the invention

The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, propose a kind of with the time changing environment adaptive pulse compression filter method for designing.This method is reference with the template according to the design of environment priori, design and the contrary wave filter that mates of environment by iterative processing, improve the correlativity between the hyperchannel, thereby improved the difficult problem that detects of target under clutter and the jamming pattern, improved the detection performance of target.

Basic ideas of the present invention are: the echo data that at first receives multiple ejected wave shape; Environment is carried out cognition, designs and the pulse compression filter time domain response figure of the contrary coupling of environment, with it as the reference template; Design the pulse compression filter that is complementary with reference template at random waveform then; With the filter process list/multiple ejected wave shape echo data that designs, isolate the pulse compression information of each waveform, from different passage output; At last to the processing that disappears mutually of the output data of each passage, finish signal such as clutter inhibition and handle.

A kind of for multiple cognitive waveform optimization disposal route of penetrating the GMTI radar system, comprise the steps:

(1) echo data of the multiple ejected wave shape of reception;

(2) environment is carried out cognition, design and the contrary pulse compression reference template that mates of environment;

(3) with reference to the random waveform pulse compression filter of reference template design with the contrary coupling of environment;

3a) initiation parameter: constraint main lobe zone, expectation information matrix C and corresponding binding occurrence g, initial weighting coefficients matrix W, iterations K;

3b) calculate weighting time domain correlation matrix B;

3c) calculate filter weights h;

3d) pulse pressure result and the reference template that obtains compared.Judge whether the pulse pressure result then stops as if coupling with template matches, and the wave filter design finishes; If do not match, then find out the minimum peak level Pr of secondary lobe as the reference level, upgrade weighting coefficient matrix W, turning back to 3b) iteration finishes Filter Design K time after meeting the demands;

When (4) with the pulse compression filter of (3) design multiple ejected wave shape echo data being handled, obtain at multiple separation that each waveform carries out pulse pressure in the multiple ejected wave shape, guarantee to have similar main sidelobe performance as far as possible, namely require same pulse pressure reference template is adopted in different transmitted waveforms;

M transmitted waveform arranged in the multiple ejected wave shape, and the constraint matrix of each waveform is

, use

Replace the C in the design of random waveform wave filter in (3);

(5) to doing the clutter inhibition of finishing dealing with that disappears mutually between the multiple ejected wave shape pulse pressure data that obtain.

Described optimization process method, step (3) is specifically carried out following steps:

Initial parameter at first is set: given main lobe zone Ω, expectation information matrix C=span (x _i) i ∈ Ω and corresponding binding occurrence g; X wherein _iBe i the column vector that receives the echo data matrix, the vector that span () expression is opened by the bracket interior element; If the main lobe scope of constraint only comprises main peak point, a C=x so ₀And g=1; The initial weighting coefficients matrix W is set; The initial value of the artificial jamming power in secondary lobe district is 1, and the initial value of the artificial jamming power in main lobe district is 0, i.e. w (i)=0 when i ∈ Ω; When

The time w (i)=1, the iteration coefficient lambda is a constant;

Calculate initial weighting time domain correlation matrix B then:

B=XWX ^* (1)

Wherein () ^*Be transpose of a matrix in the bracket;

By solving the optimization problem of belt restraining $\left\{\begin{array}{c}\underset{h}{\min }h*\mathrm{Bh}\\ s.t{C}^{*}h=g\end{array}\right.$ Draw the optimum weights h of wave filter :

h=B ^-1C(C ^*B ^-1C) ^-1g (2)

Wherein, Expression is the minimum value that variable is got the bracket interior element with h, and s.t represents constraint condition symbol, () ^-1Inverse matrix for matrix in the bracket;

Calculate time domain response y:

y=X ^*h （3）

Then pulse compression result and the reference template that obtains compared; If then stop with template matches, the wave filter design finishes; If do not match, then seek the minimum peak level Pr of secondary lobe, with it as the reference level; The position of Pr also changes in iterative process, find by the following method: the level value that the level value of a certain range unit is adjacent with its left and right sides relatively, if its level value is greater than the level value of its neighbor distance unit, left and right sides, then it is peak level, and one of minimum is minimum peak level Pr in all peak levels; Compare with the secondary lobe of reference template, should increase at its weighting coefficient of secondary lobe district that is higher than the reference template secondary lobe, and should descend at its weighting coefficient of secondary lobe zone that is lower than with reference to sidelobe level; Upgrade weighting coefficient matrix W,

$w\left(i\right)=\left\{\begin{array}{cc}0& i\∈\mathrm{\Ω}\\ \max \{w\left(i\right)+\frac{\mathrm{\λw}\left(i\right)\left[\right|y\left(i\right)|-\mathrm{Pr\; D}\left(i\right)]}{\mathrm{Pr\; D}\left(i\right)},0\}& i\∉\mathrm{\Ω}\end{array}\right.---\left(4\right)$

Wherein, the maximal value that the bracket interior element is got in max () expression, | () | the absolute value of bracket interior element is got in expression, and Pr D (i) is the degree that the reference template linear-scale of time domain pulse compression response is transformed to the minimum peak level, is called absolute level;

Recomputate time domain correlation matrix B according to the W after upgrading at last, iteration K response and template matches up to wave filter are finished Filter Design; The purpose of iteration is the maximal value that minimizes the difference of actual sidelobe level and expectation reference template sidelobe level.

Described optimization process method, step (4) is specifically carried out following steps: establishing has M transmitted waveform, the input matrix of echoed signal in the multiple ejected wave shape

With weighting time domain correlation matrix

And be expressed as respectively corresponding to the constraint matrix of m transmitted waveform:

$\tilde{X}=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{X}^m,{\tilde{C}}^m=\mathrm{span}\left(x_i^m\right),i\∈\mathrm{\Ω}---\left(5\right)$

Wherein,

Expression is to the summation of bracket interior element, X ^mBe the echo data matrix corresponding to m transmitted waveform, Be in the constraint matrix of m transmitted waveform,

Be X ^mI column vector; With X in the design of replacement step 3 wave filters, same C uses Replace, just the separable pulse compression result who obtains each transmitted waveform correspondence in the multiple ejected wave shape exports from different passages.

The present invention compared with prior art has following advantage:

The first, the designed wave filter of the present invention is applicable to any environment and the random waveform process of pulse-compression of transmitted waveform that places an order, and is applicable to the process of pulse-compression of isolating each transmitted waveform under the multiple ejected wave shape situation from echo.

The second, the designed wave filter of the present invention is reference with the template according to the design of environment priori, and is at the low secondary lobe of strong clutter district design, weak or do not have the clutter district and design high secondary lobe.Therefore it has adaptive ability, better clutter reduction.

Description of drawings

Fig. 1 is process flow diagram of the present invention;

Fig. 2 is the process flow diagram of random waveform pulse compression filter design;

Fig. 3 is the template based on the pulse compression filter of environment priori design;

The first waveform pulse compression result that Fig. 4 exports for the first passage of multiple ejected wave shape after receiving end separates that employing the inventive method obtains;

The second waveform pulse compression result that Fig. 5 exports for the second channel of multiple ejected wave shape after receiving end separates that employing the inventive method obtains;

The 3rd waveform pulse compression result that Fig. 6 exports for the third channel of multiple ejected wave shape after receiving end separates that employing the inventive method obtains;

Fig. 7 is the first and second multiple results that offset that penetrate the channel pulse packed data;

Fig. 8 is the second and the 3rd multiple result that offsets who penetrates the channel pulse packed data;

Fig. 9 is the first and the 3rd multiple result that offsets who penetrates the channel pulse packed data;

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail.

See figures.1.and.2, concrete implementation step of the present invention is as follows:

Step 1. receives the echo data X of multiple ejected wave shape;

Step 2. pair environment carries out cognition, design and the contrary pulse compression reference template D that mates of environment;

Step 3. is with reference to the random waveform pulse compression filter of reference template design with the contrary coupling of environment;

Initial parameter at first is set: given main lobe zone Ω (comprising L range unit), expectation information matrix C=span (x _i) i ∈ Ω and corresponding binding occurrence g.X wherein _iBe i the column vector that receives the echo data matrix, the vector that span () expression is opened by the bracket interior element.If the main lobe scope of constraint only comprises main peak point, a C=x so ₀And g=1.The initial weighting coefficients matrix W is set, and in fact weighting coefficient is artificial jamming power.The initial value of the artificial jamming power in secondary lobe district is 1, and the initial value of the artificial jamming power in main lobe district is 0, i.e. w (i)=0 when i ∈ Ω; When The time w (i)=1.The iteration coefficient lambda is a constant.

Calculate initial weighting time domain correlation matrix B then:

B=XWX ^* (1)

Wherein () ^*Be transpose of a matrix in the bracket.

By solving the optimization problem of belt restraining $\left\{\begin{array}{c}\underset{h}{\min }h*\mathrm{Bh}\\ s.t{C}^{*}h=g\end{array}\right.$ Draw the optimum weights h of wave filter :

h=B ^-1C(C ^*B ^-1C) ^-1g (2)

Wherein,

Expression is the minimum value that variable is got the bracket interior element with h, and s.t represents constraint condition symbol, () ^-1Inverse matrix for matrix in the bracket.

Calculate time domain response y:

y=X ^*h （3）

Then pulse compression result and the reference template that obtains compared.If then stop with template matches, the wave filter design finishes; If do not match, then seek the minimum peak level Pr of secondary lobe, with it as the reference level.It is to be noted that the position of Pr also changes in iterative process, can find by the following method: the level value that the level value of a certain range unit is adjacent with its left and right sides relatively, if its level value is greater than the level value of its neighbor distance unit, left and right sides, then it is peak level, and one of minimum is minimum peak level Pr in all peak levels.Compare with the secondary lobe of reference template, should increase at its weighting coefficient of secondary lobe district that is higher than the reference template secondary lobe, and should descend at its weighting coefficient of secondary lobe zone that is lower than with reference to sidelobe level.Upgrade weighting coefficient matrix W,

$w\left(i\right)=\left\{\begin{array}{cc}0& i\∈\mathrm{\Ω}\\ \max \{w\left(i\right)+\frac{\mathrm{\λw}\left(i\right)\left[\right|y\left(i\right)|-\mathrm{Pr\; D}\left(i\right)]}{\mathrm{Pr\; D}\left(i\right)},0\}& i\∉\mathrm{\Ω}\end{array}\right.---\left(4\right)$

Wherein, the maximal value that the bracket interior element is got in max () expression, | () | the absolute value of bracket interior element is got in expression, and Pr D (i) is the degree that the reference template linear-scale of time domain pulse compression response is transformed to the minimum peak level, is called absolute level.

Recomputate time domain correlation matrix B according to the W after upgrading at last, iteration K response and template matches up to wave filter are finished Filter Design.The purpose of iteration is the maximal value that minimizes the difference of actual sidelobe level and expectation reference template sidelobe level.

When step 4. is handled multiple ejected wave shape echo data with the pulse compression filter of step 3 design, obtain at multiple separation that each waveform carries out pulse pressure in the multiple ejected wave shape, guarantee to have similar main sidelobe performance as far as possible, namely require same pulse pressure reference template is adopted in different transmitted waveforms;

If M transmitted waveform, the input matrix of echoed signal are arranged in the multiple ejected wave shape

With weighting time domain correlation matrix

And be expressed as respectively corresponding to the constraint matrix of m transmitted waveform:

$\tilde{X}=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{X}^m,{\tilde{C}}^m=\mathrm{span}\left(x_i^m\right),i\∈\mathrm{\Ω}---\left(5\right)$

Wherein, Expression is to the summation of bracket interior element, X ^mBe the echo data matrix corresponding to m transmitted waveform,

Be in the constraint matrix of m transmitted waveform,

Be X ^mI column vector.With

X in the design of replacement step 3 wave filters, same C uses

Replace, just the separable pulse compression result who obtains each transmitted waveform correspondence in the multiple ejected wave shape exports from different passages.

Step 5. pair each passage is exported the pulse pressure data of each waveform and is done the clutter inhibition of finishing dealing with that disappears mutually.

Effect of the present invention can be illustrated by following emulation experiment:

Simulated conditions

The multiple ejected wave shape of adopting is that to utilize one group of three code length of Genetic Algorithm optimized design be 150 quadrature biphase coding signal, and a plurality of transmitting launched simultaneously by a plurality of emitting antennas.The initial parameter of wave filter optimal design is as follows: constraint main lobe scope Ω=[0], code length N=P=150, iterations are 30, iteration coefficient lambda=0.1.

Simulation result

Fig. 3 is the reference template of the pulse compression time domain response figure of the contrary coupling of a kind of environment.Based on the reference template of Fig. 3, adopt method design pulse compression filter of the present invention, Fig. 4 is the pulse compression result of first passage, and Fig. 5 is the pulse compression result of second passage, and Fig. 6 is the pulse compression result of the 3rd passage.In Fig. 6, horizontal ordinate is represented the range unit sequence number at Fig. 4, and ordinate is represented the pulse pressure output result of different distance unit, and its unit is dB.By simulation result as can be seen, output result and the template of pulse compression filter are complementary, and have proved to adopt the designed pulse compression filter of the present invention can make pulse compression result and actual environment against coupling.

Fig. 7 is the result that disappears mutually of the 1st, 2 passages, and Fig. 8 is the result that disappears mutually of the 2nd, 3 passages, and Fig. 9 is the result that disappears mutually of the 1st, 3 passages.Horizontal ordinate is represented the range unit sequence number, the surplus after ordinate is represented to disappear mutually.Can be seen by simulation result, utilize the present invention according to the wave filter of stencil design, offset after the pulse compression, surplus is little, and clutter is had the ability that suppresses preferably, and then improves the detection performance of target.

Should be understood that, for those of ordinary skills, can be improved according to the above description or conversion, and all these improvement and conversion all should belong to the protection domain of claims of the present invention.

Claims (3)

1. one kind is used for multiple cognitive waveform optimization disposal route of penetrating the GMTI radar system, it is characterized in that, comprises the steps:

(1) echo data of the multiple ejected wave shape of reception;

(2) environment is carried out cognition, design and the contrary pulse compression reference template that mates of environment;

(3) with reference to the random waveform pulse compression filter of reference template design with the contrary coupling of environment;

3a) initiation parameter: constraint main lobe zone, expectation information matrix C and corresponding binding occurrence g, initial weighting coefficients matrix W, iterations K;

3b) calculate weighting time domain correlation matrix B;

3c) calculate filter weights h;

3d) pulse pressure result and the reference template that obtains compared.Judge whether the pulse pressure result then stops as if coupling with template matches, and the wave filter design finishes; If do not match, then find out the minimum peak level Pr of secondary lobe as the reference level, upgrade weighting coefficient matrix W, turning back to 3b) iteration finishes Filter Design K time after meeting the demands;

When (4) with the pulse compression filter of (3) design multiple ejected wave shape echo data being handled, obtain at multiple separation that each waveform carries out pulse pressure in the multiple ejected wave shape, guarantee to have similar main sidelobe performance as far as possible, namely require same pulse pressure reference template is adopted in different transmitted waveforms;

M transmitted waveform arranged in the multiple ejected wave shape, and the constraint matrix of each waveform is

, use

Replace the C in the design of random waveform wave filter in (3);

(5) to doing the clutter inhibition of finishing dealing with that disappears mutually between the multiple ejected wave shape pulse pressure data that obtain.

2. optimization process method according to claim 1, it is characterized in that: step (3) is specifically carried out following steps:

Initial parameter at first is set: given main lobe zone Ω, expectation information matrix C=span (x _i) i ∈ Ω and corresponding binding occurrence g; X wherein _iBe i the column vector that receives the echo data matrix, the vector that span () expression is opened by the bracket interior element; If the main lobe scope of constraint only comprises main peak point, a C=x so ₀And g=1; The initial weighting coefficients matrix W is set; The initial value of the artificial jamming power in secondary lobe district is 1, and the initial value of the artificial jamming power in main lobe district is 0, i.e. w (i)=0 when i ∈ Ω; When

The time w (i)=1, the iteration coefficient lambda is a constant;

Calculate initial weighting time domain correlation matrix B then:

B=XWX ^* (1)

Wherein () ^*Be transpose of a matrix in the bracket;

By solving the optimization problem of belt restraining $\left\{\begin{array}{c}\underset{h}{\min }h*\mathrm{Bh}\\ s.t{C}^{*}h=g\end{array}\right.$ Draw the optimum weights h of wave filter :

h=B ^-1C(C ^*B ^-1C) ^-1g (2)

Wherein,

Expression is the minimum value that variable is got the bracket interior element with h, and s.t represents constraint condition symbol, () ^-1Inverse matrix for matrix in the bracket;

Calculate time domain response y:

y=X ^*h （3）

Then pulse compression result and the reference template that obtains compared; If then stop with template matches, the wave filter design finishes; If do not match, then seek the minimum peak level Pr of secondary lobe, with it as the reference level; The position of Pr also changes in iterative process, find by the following method: the level value that the level value of a certain range unit is adjacent with its left and right sides relatively, if its level value is greater than the level value of its neighbor distance unit, left and right sides, then it is peak level, and one of minimum is minimum peak level Pr in all peak levels; Compare with the secondary lobe of reference template, should increase at its weighting coefficient of secondary lobe district that is higher than the reference template secondary lobe, and should descend at its weighting coefficient of secondary lobe zone that is lower than with reference to sidelobe level; Upgrade weighting coefficient matrix W,

$w\left(i\right)=\left\{\begin{array}{cc}0& i\∈\mathrm{\Ω}\\ \max \{w\left(i\right)+\frac{\mathrm{\λw}\left(i\right)\left[\right|y\left(i\right)|-\mathrm{Pr\; D}\left(i\right)]}{\mathrm{Pr\; D}\left(i\right)},0\}& i\∉\mathrm{\Ω}\end{array}\right.---\left(4\right)$

Wherein, the maximal value that the bracket interior element is got in max () expression, | () | the absolute value of bracket interior element is got in expression, and Pr D (i) is the degree that the reference template linear-scale of time domain pulse compression response is transformed to the minimum peak level, is called absolute level;

Recomputate time domain correlation matrix B according to the W after upgrading at last, iteration K response and template matches up to wave filter are finished Filter Design; The purpose of iteration is the maximal value that minimizes the difference of actual sidelobe level and expectation reference template sidelobe level.

3. optimization process method according to claim 1 is characterized in that, step (4) is specifically carried out following steps: establishing has M transmitted waveform, the input matrix of echoed signal in the multiple ejected wave shape

With weighting time domain correlation matrix

And be expressed as respectively corresponding to the constraint matrix of m transmitted waveform:

$\tilde{X}=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{X}^m,{\tilde{C}}^m=\mathrm{span}\left(x_i^m\right),i\∈\mathrm{\Ω}---\left(5\right)$

Wherein, Expression is to the summation of bracket interior element, X ^mBe the echo data matrix corresponding to m transmitted waveform,

Be in the constraint matrix of m transmitted waveform,

Be X ^mI column vector; With X in the design of replacement step (3) wave filter, same C uses

Replace, just the separable pulse compression result who obtains each transmitted waveform correspondence in the multiple ejected wave shape exports from different passages.

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