CN103885052B - A kind of polar echo separation method of wide cut complete polarization satellite-borne SAR - Google Patents

Abstract

A polarization-echo separation method for wide-width full-polarization spaceborne SAR. Wide-width full-polarization spaceborne SAR refers to transmitting H and V polarization pulses sequentially within a pulse repetition interval, and then using dual polarization channels to receive echo, thereby obtaining a new system of four polarization components. This new type of fully polarized SAR does not increase the system repetition frequency, so a wider survey swath can be obtained. However, to obtain this performance improvement, the echoes of differently polarized pulses must first be separated. This method is improved on the basis of the traditional linear constrained minimum variance (LCMV) algorithm: the traditional algorithm is split, and FIR filtering is introduced between the two split steps, and then the second step is improved and adjusted accordingly . According to the method to achieve polarization echo separation, on the one hand, the separation and isolation of different polarization echoes can meet the application requirements;

Description

A Polarization Echo Separation Method for Wide Span Fully Polarized Spaceborne SAR

technical field

The present invention provides a novel polarization echo separation method for the key problem of the wide-range full-polarization space-borne SAR system in the new system—separation and processing of aliasing echoes, which mainly involves two technologies of microwave remote sensing and signal processing field.

Background technique

By transmitting different polarization pulses and receiving echoes through dual polarization channels, fully polarized spaceborne SAR can obtain the scattering information of each resolution unit under different polarization combinations, which helps to further understand the backscattering characteristics of the target . Therefore, compared with single-polarization SAR, full-polarization SAR can provide richer target information, which is helpful to determine the target scattering mechanism, improve the ability to detect, identify and classify targets, and to detect received clutter interference. inhibition. Due to the introduction of full polarization technology, the application field of SAR has been greatly expanded. Through full-polarization SAR images, we can extract more information, which plays an inestimable role in fields such as agricultural and forestry monitoring, hydrogeography, urban planning, disaster assessment, and military reconnaissance.

A series of full-polarization spaceborne SAR systems currently in orbit (such as TerraSAR-X of De Aerospace, RADARSAT-2 of the Canadian Space Agency, etc.) use alternate transmission of H/V polarization pulses and dual-polarization channel reception The combination of echoes is used to realize full-polarization earth observation imaging, and the transmission interval of the two polarization pulses is the pulse repetition interval (PRI, Pulse repetition interval), as shown in Figure 1(a). This polarization method needs to double the PRF of the system to avoid the deterioration of azimuth ambiguity, resulting in a half of the imaging width and a reduction in the frequency of revisit observations, which is also the biggest drawback of the current fully polarized spaceborne SAR.

In order to solve the above problems, German Aerospace DLR proposed a new full-polarization spaceborne SAR system in 2008. This system will continuously transmit two kinds of polarization pulses during a pulse transmission (shown in Figure 1(b) As shown in Figure 2), at the receiving end and then received through the dual polarization channel, all four polarization components can be theoretically obtained, and there is no need to increase the system PRF to achieve full polarization observation. After this system was put forward, the theoretical feasibility of it was unanimously recognized at home and abroad, but at the same time, it was believed that the biggest obstacle to the realization of this system engineering was the temporal aliasing of different polarization pulse echoes. If they cannot be effectively separated, the individual polarization components cannot be extracted.

Regarding the issue of echo separation, DLR has not published any public documents or patents in recent years, so it is impossible to know the progress of the agency's work in this area through public channels. On the domestic front, Qi Weikong of the Institute of Electronics, Chinese Academy of Sciences published an article titled "Research on a New Multi-polarization Spaceborne SAR Working Method" in the journal "Chinese Science E" to study and solve this problem , the method described in this paper needs to complete the range compression processing on the satellite, and then carry out the null trap suppression processing one by one. Since the distance compression needs to be completed on the star, the calculation amount on the star is greatly increased, and the demand on the resources on the star is very high, which is difficult to realize in engineering. In short, up to now, no engineering-realizable solutions for the above-mentioned problems have been published in the public literature.

Contents of the invention

The technical problem of the present invention is: to overcome the deficiencies of the prior art, and aiming at the echo aliasing problem of the new system full-polarization spaceborne SAR, the present invention proposes a new type of elevation digital beamforming method. This method improves the Linear Constraint Minimum Variance (LCMV) algorithm used in traditional zero-pointing processing, and forms two digital receiving beams in the elevation direction to realize spatial filtering (see Figure 3), which is completed during echo reception. The separation of the two polarization echoes is achieved.

Technical solution of the present invention is:

A polarization echo separation method for wide-width full-polarization spaceborne SAR, the polarization echo is the echo corresponding to the H polarization pulse and the V polarization pulse transmitted sequentially within a pulse repetition interval, and the two The echoes return to the receiver simultaneously from different viewing angle positions in the echo receiving window, thereby aliasing in the time domain; the steps of the separation method are as follows:

(1) Perform low-noise amplification, down-conversion and ADC sampling processing on the echoes received in each receiving channel of the planar phased array antenna in turn, and convert the high-frequency analog signal corresponding to the original echo into a low-frequency digital signal;

(2) Use the real-time arrival vectors v1 and v2 _of the H-polarized pulse and V-polarized pulse to weight the low-frequency digital signal obtained in step ( ₁ ) respectively, where the pitch is towards the k-th receiving channel The low-frequency digital signal is weighted by the kth elements w _1k and w _2k of v ₁ and v ₂ respectively, k is a positive integer, and k∈[1,N _e ], N _e is the number of receiving channels;

(3) Perform corresponding FIR filtering processing on the two signals weighted by different weights v ₁ and v ₂ in each receiving channel in the pitch direction;

(4) The signal vectors processed by the weighted vector v ₁ and the FIR filter output by each receiving channel are accumulated and synthesized to output, and a signal is generated; the signal vectors processed by the weighted vector v ₂ and the FIR filter output by each receiving channel are accumulated Composite output to generate another signal;

(5) Through the first set of weighted vectors The two-way signals obtained in step (4) are weighted and synthesized to obtain the echo signal of the first H-polarized pulse transmitted during a complete pulse transmission period;

(6) Through the second set of weighted vectors The two signals obtained in step (4) are weighted and synthesized to obtain the echo signal of the second transmitted V-polarized pulse during a complete pulse transmission period.

The arrival vectors v ₁ and v ₂ of the two sequentially transmitted H-polarized pulses and V-polarized pulses in the step (2) are time-varying, and their expressions are respectively and The kth element in the wave of arrival vector can be expressed as $W_{\mathrm{ik}}=\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}(k-1)d\&Center\; Dot;\sin [{\mathrm{\θ}}_i\left(\mathrm{\τ}\right)\left]\right\}(i=\mathrm{1,2}),$ When i=1, it represents the H polarization pulse, and when i=2, it represents the V polarization pulse;

Where λ is the wavelength, d is the receiving channel spacing in the pitch direction, θ _i (τ) is the angle of arrival corresponding to the echo of the H-polarized pulse (i=1) or V-polarized pulse (i=2) at time τ, Its calculation method is carried out as follows:

(a) Calculate the instantaneous slant distance R corresponding to the echo of the H-polarized pulse at time τ by the formula R(τ)=c·τ/2; where c is the speed of light; the slant distance of the echo of the V-polarized pulse can be expressed as is R'(τ)=c·(τ-T)/2, where T is the emission interval between two polarized pulses;

(b) According to the instantaneous slope distance R(τ) calculated in step (a), according to the formula Solve the instantaneous sub-satellite point angle α(τ) of the H-polarized pulse echo, where R _e is the radius of the earth, and H is the satellite orbit height;

(c) According to the angle of view of the sub-satellite point α _c in the normal direction of the antenna and the angle of view of the instantaneous echo sub-satellite point α(τ) calculated in step (b), use the formula θ(τ)=α(τ)-α _c Obtain the corresponding angle of arrival of the echo.

The FIR filter in the step (3) is an 8th-order time-delay filter, and the time delay corresponding to the kth receiving channel in the pitch direction is where K _r is the chirp frequency of the transmitted pulse, is the first-order partial derivative of the angle of arrival θ(τ) with respect to the range fast time _τ when the pulse passes through the scene center time τc.

The weighted vectors in the steps (5) and (6) are respectively the first row and the second row of the matrix N _e [(V') ^H V'] ^-1 , where (V') ^H V' is obtained by the following formula:

${\left(v^{\′}\right)}^h{v}^{\′}=\left[\begin{array}{cc}\underset{k=1}{\overset{N_e}{\mathrm{\Σ}}}{f^{\′}}_{11k}\left(\mathrm{\τ}\right)& \underset{k=1}{\overset{N_e}{\mathrm{\Σ}}}{f^{\′}}_{12k}\left(\mathrm{\τ}\right)\\ \underset{k=1}{\overset{N_e}{\mathrm{\Σ}}}{f^{\′}}_{\mathrm{twenty\; one}k}\left(\mathrm{\τ}\right)& \underset{k=1}{\overset{N_e}{\mathrm{\Σ}}}{f^{\′}}_{\mathrm{twenty\; two}}k\left(\mathrm{\τ}\right)\end{array}\right],$ The elements f' _ijk (τ) shown in the matrix can be expressed as

${f^{\′}}_{\mathrm{ilk}}\left(\mathrm{\τ}\right)=\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}(k-1)d\&Center\; Dot;\{\sin \left[{\mathrm{\θ}}_j(\mathrm{\τ}+{\mathrm{D.}}_k)\right]-\sin \left[{\mathrm{\θ}}_i(\mathrm{\τ}+{\mathrm{D.}}_k)\right]\left\}\right\},$ i,j=1,2,k∈[1,N _e ], θ ₂ represents the angle of arrival of the V-polarized pulse, and θ ₁ represents the angle of arrival of the H-polarized pulse.

The beneficial effect of the present invention compared with prior art is:

(1) Compared with the traditional zero-point pointing treatment, the present invention takes into account the influence of pulse ductility on separation performance. Since the sub-pulse has a certain pulse width, it will cover a certain area on the ground at a certain moment, while the traditional zero-point pointing method can only achieve the maximum gain reception (signal sub-pulse)/deepest in the center of the covered area. Null suppression (interfering sub-pulse), but the same gain reception as the central position cannot be realized for other areas, so the isolation is poor, and the present invention can improve the isolation by about 10dB, so that two kinds of polarization echoes are in the whole The isolation within the receiving window is greater than 25dB, which meets the requirements of most polarimetric SAR applications.

(2) The present invention splits the one-step weighted synthesis processing of the traditional zero-point point into two steps, and introduces an 8-order FIR filter between the two-step weighted processing (shown in Figure 4). Compared with the echo separation process that performs range compression first and then performs zero-pointing processing one by one, this greatly reduces the system structure and corresponding processing calculations on the star, which is conducive to engineering realization.

Description of drawings

Figure 1 is a comparison between the traditional system and the new system full-polarization spaceborne SAR scheme, where Figure 1(a) is the full-polarization scheme of the traditional system, and Figure 1(b) is the full-polarization scheme of the new system;

Figure 2 is the pulse emission timing diagram of the wide-field full-polarization spaceborne SAR system of the new system;

Figure 3 shows two digital beams formed by the DBF in elevation to separate polarization echoes at different positions;

Fig. 4 is the corresponding 8-order FIR filter processing block diagram in pitching to the kth sub-aperture;

Figure 5 is a system block diagram in which the traditional zero-point pointing based on the LCMV algorithm is divided into two steps;

Fig. 6 is a schematic diagram of the polarization echo separation method of the present invention.

detailed description

The innovations and specific implementation methods of the present invention will be described in detail below in conjunction with the accompanying drawings.

Since the two kinds of polariton pulses (H and V polarization pulses) of the new wide-width full-polarization spaceborne SAR are transmitted sequentially, at any moment in the echo receiving window, the H and V polarization The echoes of the pulse will return to the receiver from different viewing angles, and contain surface information in different areas (shown in Figure 3). According to this difference, we can use digital beamforming (DBF) technology to form two real-time scanning receiving beams at the receiving end to receive the echoes of H and V polarized pulses respectively, and each beam has the following two characteristics:

1. Maximum gain to receive the echo of the corresponding sub-pulse

2. The deepest null suppresses the echo of the interfering sub-pulse

Among various beamforming algorithms, the linear constrained minimum variance (LCMV) method can achieve the above two

aspect performance. This algorithm is governed by the following set of equations:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1.1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1.2</span>}<span\; class="notranslate">\; )</span>$

Where i,j∈[1,2] (when the subscript i,j=1 indicates that the relevant parameter is the relevant parameter of the H polarization pulse, i,j=2 indicates that the parameter is the relevant parameter of the V polarization pulse), the symbol (· ) ^H represents the conjugate transpose, w _i represents the weight vector forming the i-th sub-beam, N _e represents the number of receiving sub-apertures (number of receiving channels) in the elevation direction, v _i and v _j represent the i-th and j-th sub-beams respectively The steering vector corresponding to the pulse (steeringvecotr), they can be expressed as

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; j</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; j</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2.1</span>}<span\; class="notranslate">\; )</span>$

and

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; j</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; j</span>}\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Where (·) ^T is the transposition symbol, d is the sub-aperture interval in the pitch direction, λ is the wavelength, θ _i and θ _j respectively represent the normal offset angle in the pitch direction corresponding to the i-th sub-pulse echo ( off-boresight angle), that is, the wave angle. Since the sub-pulse travels on the ground, the steering vectors v _i and v _j are time-varying, which also determines that the corresponding weighting vectors w _i and w _j are time-varying.

Based on formula (2.1) and formula (2.2), the multiple matrix V of the receiving array is defined as

V=[v ₁ ,v ₂ ](3)

Therefore, the constraints (1.1) and (1.2) on the beamforming weight vector w _i can be expressed as a matrix equation

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Where e _i is the ith column of a 2×2 identity matrix. By solving the above equations, we can obtain the weight vector w _i for forming the i-th receive sub-beam as

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; tn</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; tn</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Among them, S _tn is the covariance matrix (spectralmatrix) of receiver noise. This noise can be modeled as white noise with power Then S _tn can be written as

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; tn</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; tn</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; \&times;</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

in is a N _e -dimensional identity matrix. Put formula (6) into formula (5), then can be simplified to

${\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

However, since the pulse has a certain pulse width, it has certain ductility on the ground, and the i-th receive sub-beam formed by the weight vector represented by equation (7) can only form the maximum gain/deepest beam at a certain position Zero-sinking, the remaining positions cannot obtain the same receiving gain as the center position, which will cause insufficient separation in the later stage.

In response to this problem, we will make the following three innovative improvements to the traditional zero-point processing to achieve better separation effects:

(1) The traditional LCMV weighted synthesis process represented by formula (7) is divided into two steps. The first step is to use the two row vectors contained in the matrix VH to weight and synthesize the original signal received by the pitch array; the second step is to use the row vector Weighted synthesis is performed on the two signals output in the first step. Figure 5 shows a schematic diagram of splitting the traditional LCMV weighting process into two steps.

(2) By analyzing the signal characteristics of the SAR echo after the first step of processing, after the first step is completed, FIR filtering is introduced into each channel in the pitch direction, and the filter system response function of the kth sub-aperture

${\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; FIR</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; j</span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Where K _r is the frequency modulation signal of the transmitted pulse, (d is the pitch sub-aperture interval, λ is the wavelength, is the one-section partial differential of the echo angle of view at the center of the echo window with respect to the fast time τ in the range direction). The phase of H _{FIR_k} (f) is a linear function of frequency f, and this system transfer function corresponds to delay processing in the time domain, which can be realized by an 8-point sinc interpolation kernel on the star (shown in Figure 3).

(3) After the FIR filtering process, according to the signal characteristics again, the vector of the second step weighting process after the LCMV split Corrected accordingly, changing it to The coherent combination between signals is guaranteed, so that the optimal echo separation effect can be finally obtained.

Note:

${\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>& \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>& \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

in ${f^{\&prime;}}_{\mathrm{ilk}}\left(\mathrm{\&tau;}\right)=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&CenterDot;\{\sin \left[{\mathrm{\&theta;}}_j\left(\mathrm{\&tau;}\right)\right]-\sin \left[{\mathrm{\&theta;}}_i(\mathrm{\&tau;}+{\mathrm{D.}}_k)\right]\left\}\right\},$ And (V') ^H V' is

${<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; v</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; v</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; 11</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>& \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; 12</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\\ \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; one</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>& \underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}^{<span\; class="notranslate">\; \&prime;</span>}}_{\mathrm{<span\; class="notranslate">\; twenty\; two</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; )</span>\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

in ${f^{\&prime;}}_{\mathrm{ilk}}\left(\mathrm{\&tau;}\right)=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&Center\; Dot;\{\sin \left[{\mathrm{\&theta;}}_j(\mathrm{\&tau;}+{\mathrm{D.}}_k)\right]-\sin \left[{\mathrm{\&theta;}}_i(\mathrm{\&tau;}+{\mathrm{D.}}_k)\right]\left\}\right\},$ in the formula ${\mathrm{D.}}_k=\frac{(k-1)}{K_r}{f}_0.$

In the specific implementation process, it is first required that the fully polarized spaceborne SAR has multiple receiving sub-apertures in the elevation direction (shown in Figure 3). After the echo received by each receiving sub-aperture is subjected to low-noise amplifier, down-conversion and ADC sampling, it is implemented according to the following process:

(1) The digital echo signal is weighted by using the first step in the split traditional zero pointing process;

(2) Perform corresponding delay processing on the weighted signal in step (1) through the corresponding FIR filter in each pitch receiving sub-aperture;

(3) Finally, by using the second step of the improved null-pointing processing, the signals obtained in step (2) are correspondingly weighted and synthesized to obtain the separated H and V polarization echoes.

The method designed by the present invention can meet the separation requirements of different polarization echoes in practical applications, and has low demand for on-board computation, and can realize real-time separation on-board. The corresponding system processing block diagram is shown in Figure 6, and the steps are as follows:

(1) Perform low-noise amplification, down-conversion and ADC sampling processing on the echoes received in each receiving channel of the planar phased array antenna in turn, and convert the high-frequency analog signal corresponding to the original echo into a low-frequency digital signal;

(2) Use the real-time arrival vectors v1 and v2 _of the H-polarized pulse and V-polarized pulse to weight the low-frequency digital signal obtained in step ( ₁ ) respectively, where the pitch is towards the k-th receiving channel The low-frequency digital signal is weighted by the kth elements w _1k and w _2k of v ₁ and v ₂ respectively, k is a positive integer, and k∈[1,N _e ], N _e is the number of receiving channels;

The arrival vectors v1 and v2 _of the _two sequentially transmitted H-polarized pulses and V-polarized pulses are time-varying, and their expressions are respectively The kth element in the wave of arrival vector can be expressed as $W_{\mathrm{ik}}=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&Center\; Dot;\sin [{\mathrm{\&theta;}}_i\left(\mathrm{\&tau;}\right)\left]\right\}(i=\mathrm{1,2}),$ When i=1, it represents the H polarization pulse, and when i=2, it represents the V polarization pulse;

where λ is the wavelength, d is the receiving channel spacing in the pitch direction, θ _i (τ) is the i-th sub-pulse echo (i=1 is the H polaroid sub-pulse, i=2 is the V polaroid sub-pulse) corresponding to The angle of arrival is calculated according to the following steps:

(a) Calculate the instantaneous slant distance R corresponding to the echo of the H-polarized pulse at time τ by the formula R(τ)=c·τ/2; where c is the speed of light; the slant distance of the echo of the V-polarized pulse can be expressed as is R'(τ)=c·(τ-T)/2, where T is the emission interval between two polarized pulses;

(b) According to the instantaneous slope distance R(τ) calculated in step (a), according to the formula

Solve the instantaneous sub-satellite point angle α(τ) of the H-polarized pulse echo, where R _e is the radius of the earth, and H is the satellite orbit height;

(c) According to the angle of view of the sub-satellite point α _c in the normal direction of the antenna and the angle of view of the instantaneous echo sub-satellite point α(τ) calculated in step (b), use the formula θ(τ)=α(τ)-α _c Obtain the corresponding angle of arrival of the echo.

(3) Perform corresponding FIR filtering processing on the two signals weighted by different weights v ₁ and v ₂ in each receiving channel in the pitch direction;

The FIR filter is an 8th-order time delay filter, and the corresponding time delay of the pitching kth receiving channel is where K _r is the chirp frequency of the transmitted pulse, is the first-order partial derivative of the angle of arrival θ(τ) with respect to the range fast time _τ when the pulse passes through the scene center time τc.

(4) The signal vectors processed by the weighted vector v ₁ and the FIR filter output by each receiving channel are accumulated and synthesized to output, and a signal is generated; the signal vectors processed by the weighted vector v ₂ and the FIR filter output by each receiving channel are accumulated Composite output to generate another signal;

(5) Through the first set of weighted vectors The two-way signals obtained in step (4) are weighted and synthesized to obtain the echo signal of the first H-polarized pulse transmitted during a complete pulse transmission period;

(6) Through the second set of weighted vectors The two signals obtained in step (4) are weighted and synthesized to obtain the echo signal of the second transmitted V-polarized pulse during a complete pulse transmission period.

Weight vectors in steps (5) and (6) are respectively the first row and the second row of the matrix N _e [(V') ^H V'] ^-1 , where (V') ^H V' is obtained by the following formula:

${\left(v^{\&prime;}\right)}^h{v}^{\&prime;}=\left[\begin{array}{cc}\underset{k=1}{\overset{N_e}{\mathrm{\&Sigma;}}}{f^{\&prime;}}_{11k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\mathrm{\&Sigma;}}}{f^{\&prime;}}_{12k}\left(\mathrm{\&tau;}\right)\\ \underset{k=1}{\overset{N_e}{\mathrm{\&Sigma;}}}{f^{\&prime;}}_{\mathrm{twenty\; one}k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\mathrm{\&Sigma;}}}{f^{\&prime;}}_{\mathrm{twenty\; two}}k\left(\mathrm{\&tau;}\right)\end{array}\right],$ The elements f' _ijk (τ) shown in the matrix can be expressed as

${f^{\&prime;}}_{\mathrm{ilk}}\left(\mathrm{\&tau;}\right)=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&Center\; Dot;\{\sin \left[{\mathrm{\&theta;}}_j(\mathrm{\&tau;}+{\mathrm{D.}}_k)\right]-\sin \left[{\mathrm{\&theta;}}_i(\mathrm{\&tau;}+{\mathrm{D.}}_k)\right]\left\}\right\},$ i,j=1,2,k∈[1,N _e ], θ ₂ represents the angle of arrival of the V-polarized pulse, and θ ₁ represents the angle of arrival of the H-polarized pulse.

The content that is not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims (5)

1. a polar echo separation method for wide cut complete polarization satellite-borne SAR, described polar echo is oneH polarization pulse and the corresponding echo of V polarization pulse in individual pulse recurrence interval, launched successively, these are two years oldPlant echo be back to receiver from different positions, visual angle simultaneously in echo receiver window, thereby in time domainAliasing; It is characterized in that: the step of described separation method is as follows:

(1) to Planar Phased Array Antenna pitching, upwards received echo is successively in each receive pathCarry out low noise amplification, down coversion and ADC sampling processing, by high frequency simulation corresponding original echoSignal becomes low-frequency digital signal;

(2) utilize the real-time ripple of described H polarization pulse and V polarization pulse to reach vector v₁With v₂Right respectivelyThe low-frequency digital signal that step (1) obtains is weighted processing, and wherein pitching receives logical to kThe low-frequency digital signal in road is respectively by v₁With v₂K element w_1kWith w_2kWeighting, k is positive integer, andk∈[1,N_e],N_eFor the number of receive path;

(3) by pitching to two-way in each receive path through different weights v₁With v₂The signal of weighting carries outCorresponding FIR filtering processing;

(4) the process weight vectors v of each receive path output₁And the signal of FIR filter processVector adds up and synthesizes output, generates a road signal; The process weight vectors of each receive path outputv₂And the synthetic output that adds up of the signal phasor of FIR filter process, generate another road signal;

(5) by first group of weight vectorsThe two paths of signals that step (4) is obtained addsPower synthetic output, obtains the H polarization pulse of first transmitting during a complete impulse ejectionEcho-signal;

(6) by second group of weight vectorsThe two paths of signals that step (4) is obtained addsThe synthetic output of power, obtains the returning of V polarization pulse of second transmitting during a complete impulse ejectionRipple signal.

2. the polar echo separation side of a kind of wide cut complete polarization satellite-borne SAR according to claim 1Method, is characterized in that: two described H polarization pulse and V that launch successively in described step (2)The ripple of polarization pulse reaches vector v₁With v₂While being, become, its expression formula is respectivelyWithK the element that ripple reaches in vector can be expressed asWherein, i=1,2, i=1 interval scale H polarization pulse, i=2Interval scale V polarization pulse;

Wherein λ is that wavelength, d are that pitching is to receive path interval, θ_i(τ) be H polarization pulse, wherein i=1;Or the echo of V polarization pulse is at Bo Dajiao corresponding to τ moment, wherein i=2; Its account form by asLower step is carried out:

(a) calculate corresponding instantaneous at the echo of τ moment H polarization pulse by formula R (τ)=c τ/2Oblique distance R; Wherein c is the light velocity; The oblique distance of V polarization pulse echo can be expressed as R'(τ)=c (τ-T)/2, itsMiddle T is two transmission intervals between polarization pulse;

(b) according to the instantaneous oblique distance R (τ) calculating in step (a), according to formulaSolve the instantaneous substar visual angle of H polarization pulse echoα (τ), wherein R_eFor earth radius, H is satellite orbital altitude;

(c) according to antenna pitching to normal direction substar visual angle α_cAnd the wink calculating in step (b)Shi Huibo substar visual angle α (τ), utilizes formula θ (τ)=α (τ)-α_cTry to achieve the corresponding ripple of echo and reach angle.

3. the polar echo separation side of a kind of wide cut complete polarization satellite-borne SAR according to claim 1Method, is characterized in that: the FIR wave filter in described step (4) is one 8 rank Time-Delay Filters, bowsFace upward to k the corresponding delay volume of receive path and beWherein K_rFor transmittingThe linear frequency modulation rate of pulse,For passing through scene center moment τ in pulse_cIt is right that Shi Bo reaches angle θ (τ)Distance is to the single order local derviation of fast time τ.

4. the polar echo separation side of a kind of wide cut complete polarization satellite-borne SAR according to claim 1Method, is characterized in that: the weight vectors in described step (5)For matrix N_e[(V')^HV']^-1'sThe first row, wherein, (V')^HV' is obtained by following formula: ${\left(V^{\&prime;}\right)}^H{V}^{\&prime;}=\left[\begin{array}{cc}\underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{11k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{12k}\left(\mathrm{\&tau;}\right)\\ \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{21k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{22k}\left(\mathrm{\&tau;}\right)\end{array}\right],$ Element f' shown in matrix_ijk(τ) can be expressed as ${f^{\&prime;}}_{ijk}\left(\mathrm{\&tau;}\right)=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&CenterDot;\{sin\&lsqb;{\mathrm{\&theta;}}_j(\mathrm{\&tau;}+D_k)\&rsqb;-sin\&lsqb;{\mathrm{\&theta;}}_i(\mathrm{\&tau;}+D_k)\&rsqb;\left\}\right\},$ i,j＝1,2,k∈[1,N_e]，θ₁GenerationThe Bo Dajiao of table H polarization pulse, θ₂Represent the Bo Dajiao of V polarization pulse.

5. the polar echo separation side of a kind of wide cut complete polarization satellite-borne SAR according to claim 1Method, is characterized in that: the weight vectors in described step (5) and (6)For matrixN_e[(V')^HV']^-1The second row, wherein, (V')^HV' is obtained by following formula:

${\left(V^{\&prime;}\right)}^H{V}^{\&prime;}=\left[\begin{array}{cc}\underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{11k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{12k}\left(\mathrm{\&tau;}\right)\\ \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{21k}\left(\mathrm{\&tau;}\right)& \underset{k=1}{\overset{N_e}{\&Sigma;}}{f^{\&prime;}}_{22k}\left(\mathrm{\&tau;}\right)\end{array}\right],$ Element f' shown in matrix_ijk(τ) can be expressed as ${f^{\&prime;}}_{ijk}\left(\mathrm{\&tau;}\right)=\exp \{j\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}(k-1)d\&CenterDot;\{sin\&lsqb;{\mathrm{\&theta;}}_j(\mathrm{\&tau;}+D_k)\&rsqb;-sin\&lsqb;{\mathrm{\&theta;}}_i(\mathrm{\&tau;}+D_k)\&rsqb;\left\}\right\},$ i,j＝1,2,k∈[1,N_e]，θ₁GenerationThe Bo Dajiao of table H polarization pulse, θ₂Represent the Bo Dajiao of V polarization pulse.