CN102944876A - Efficient three-dimensional imaging method of broadband monopulse radar - Google Patents

Abstract

The invention provides an efficient three-dimensional imaging method of a broadband monopulse radar. The method includes selecting pulse signals of a target in multiframe different sampling instants respectively from a sum channel echo signal and a difference channel echo signal received by the broadband monopulse radar; subjecting each frame of pulse signal to pulse compression treatment respectively to obtain one-dimensional high resolution range profiles of the target at different sampling instants; subjecting each frame of one-dimensional high resolution range profile to monopulse three-dimensional imaging of the target respectively to obtain three-dimensional images of the target under radar coordinate system at different sampling instants; converting the three-dimensional images of the target under the radar coordination system corresponding to each frame to a unified reference coordinate system; and combining the three-dimensional images of the frames of the target to form a final three-dimensional image of the target. The provided target three-dimensional imaging method can improve the efficiency of the monopulse radar three-dimensional imaging processing.

Description

A kind of efficient broadband monopulse radar three-D imaging method

Technical field

The embodiment of the invention relates to image data processing technique, relates in particular to a kind of efficient broadband monopulse radar three-D imaging method.

Background technology

The high-resolution radar image that obtains target by synthetic-aperture radar (Synthetic Aperture Radar, SAR) or inverse synthetic aperture radar (ISAR) (Inverse Synthetic Aperture Radar, ISAR) is the effective means of target identification.The sea Ship Target generally is in operational configuration, and driven by wave, has six-freedom motion, i.e. rolling, pitching, driftage, swaying, surging and heave, and therefore, the sea Ship Target has complicated motility characteristics.Utilize the moving ship targets image of SAR or ISAR acquisition, often be difficult to reflect the true form of target scattering.In radar detection, imaging and the identification of some close together are used, utilize one-dimensional distance high-resolution and the bidimensional angle measurement ability of broadband monopulse radar that target is carried out three-dimensional imaging, extract the three-dimensional scattering structural information of target, target is classified and key position identification, just become a kind of inevitable choice of technology.

In the existing monopulse 3 Dimension Image Technique, the three-D imaging method that is based on ISAR that generally uses, at first utilize pulse compression technique, the echoed signal that the broadband monopulse radar is obtained in the time at coherent accumulation and channel signal, gun parallax signal and trim signal are processed, wherein, after the processing and the high-resolution one-dimensional range profile time series corresponding target of channel signal, then according to the range-aligned algorithm to carrying out apart from coarse alignment with channel signal and poor channel signal, the recycling phase compensating method to, poor channel signal carries out the meticulous compensation of phase place, and adjust the distance aim at and phase compensation after with, poor channel signal carries out respectively the orientation to inverse Fourier transform, extract through target scattering center again, the steps such as phase-shift detection obtain the distance at target strong scattering center, position angle and the angle of pitch are to construct the three-dimensional image of target.Wherein, the clearly ISAR image of Ship Target be obtained, accurately range-aligned and meticulous motion compensation must be carried out.

Therefore, prior art is complicated to the imaging processing process of the sea Ship Target that has compound movement, and efficient is low.

Summary of the invention

The embodiment of the invention provides a kind of broadband monopulse radar three-D imaging method, the efficient of processing in order to improve the monopulse radar three-dimensional imaging.

The embodiment of the invention provides a kind of broadband monopulse radar three-D imaging method, comprising:

Receive from the broadband monopulse radar with passage echoed signal and poor passage echoed signal, choose respectively target at the pulse signal of the different sampling instants of multiframe;

Respectively every frame pulse signal is carried out process of pulse-compression, to obtain the high resolution range profile of the different sampling instants of target;

Respectively every frame high resolution range profile is carried out the monopulse three-dimensional imaging of target, obtain the three-dimensional image of target under the radar fix system of different sampling instants;

With the three-dimensional image of target under radar fix system corresponding to each frame, be transformed under the unified reference frame;

Three-dimensional image to each frame of target makes up, and forms the final three-dimensional image of target.

The technical scheme that the embodiment of the invention provides, by the respectively three-dimensional imaging of establishing target under radar fix system of high resolution range profile that utilizes the different sampling instants of multiframe, and the three-dimensional image of target under radar fix corresponding to each frame system be transformed under the unified reference frame, again the three-dimensional image of each frame of target made up, the three-dimensional imaging of realize target, thereby avoided the signal of large amount of complex to process computing, improved the efficient that the monopulse radar three-dimensional imaging is processed.

Description of drawings

Fig. 1 is the process flow diagram of broadband monopulse radar three-D imaging method embodiment one of the present invention;

Fig. 2 is the static Texas tower imaging geometry figure of the embodiment of the invention;

Fig. 3 is the motion Texas tower imaging geometry figure of the embodiment of the invention;

Fig. 4 is Ship Target scattering point illustraton of model;

Fig. 5 is the process flow diagram of broadband monopulse radar three-D imaging method embodiment two of the present invention;

Fig. 6 ~ Figure 11 is the monopulse radar three-dimensional imaging figure of the Ship Target scattering point model among Fig. 5.

Embodiment

Fig. 1 is the process flow diagram of broadband monopulse radar three-D imaging method embodiment one of the present invention.The method is applicable to the signal that the broadband monopulse radar receives is processed, and to form the 3-D view of target under monopulse radar, is specially adapted to the imaging to dynamic object, such as marine naval vessel etc.For being described clearly, this paper will be example as target take the naval vessel, and implementation is described.The method can be carried out by the server that possesses data-handling capacity or controller, and as shown in Figure 1, the method for the present embodiment can comprise:

S101, receive from the broadband monopulse radar with passage echoed signal and poor passage echoed signal, choose respectively target at the pulse signal of the different sampling instants of multiframe;

Wherein, differ from the passage echoed signal and comprise gun parallax passage echoed signal and trim passage echoed signal.Concrete, there are relative motion usually in radar observation platform and Ship Target, so that Ship Target changes in time with respect to the state of radar beam sight line, therefore, process at the pulse signal of the different sampling instants of multiframe by choosing target, the variation that occurs in time to reflect the target scattering feature, and then the resolution in time of realize target scattering center.

S102, respectively every frame pulse signal is carried out process of pulse-compression, to obtain the high resolution range profile of the different sampling instants of target;

Concrete, utilize pulse compression technique to carrying out pulse compression with passage echoed signal and poor passage echoed signal, and the passage echoed signal namely obtain the high resolution range profile of target after pulse compression.

S103, every frame high resolution range profile is carried out the monopulse three-dimensional imaging of target respectively, obtain the three-dimensional image of target under the radar fix system of different sampling instants;

Concrete, according to predefined threshold value, the high resolution range profile of target is extracted the strong scattering center of target, and further extract the complex signal of target scattering point, carry out again normalized, finally obtain distance, position angle and the angle of pitch at target strong scattering center, and then obtain the three-dimensional image of target under radar fix system.

S104, with the three-dimensional image of target under radar fix corresponding to each frame system, be transformed under the unified reference frame;

Concrete, can according to the relation of each sampling instant Texas tower and reference frame, by coordinate translation and rotational transform, the three-dimensional image of target under radar fix system corresponding to each frame be transformed under the unified reference frame.

S105, the three-dimensional image of each frame of target is made up, form the final three-dimensional image of target.

Concrete, the three-dimensional image of each frame of target under unified reference frame made up, obtain the final three-dimensional image of target.

In the present embodiment, by the respectively three-dimensional imaging of establishing target under radar fix system of high resolution range profile that utilizes the different sampling instants of multiframe, and the three-dimensional image of target under radar fix corresponding to each frame system be transformed under the unified reference frame, again the three-dimensional image of each frame of target made up, the three-dimensional imaging of final realize target, avoid the signal of large amount of complex to process computing, improved the efficient that the monopulse radar three-dimensional imaging is processed.

Aforesaid broadband monopulse radar three-D imaging method, wherein, corresponding radar fix is identical or not identical under the different sampling instants of each frame.

Concrete, for static Texas tower, be identical at radar fix corresponding to the different sampling instants of each frame; For the Texas tower of motion, target is not identical in radar fix system corresponding to the different sampling instants of each frame.

Fig. 2 is the static Texas tower imaging geometry figure of the embodiment of the invention.As shown in Figure 2, o _rx _ry _rz _rBe radar fix system, OXYZ is reference frame, and oxyz is the Ship Target body coordinate system, and the Texas tower height is H.Because the position of Texas tower does not change in time, the target three-dimensional image that is obtained by each frame high resolution range profile is positioned under the same radar fix system constantly in difference, therefore, radar fix system is consistent with reference frame in fact, can directly under radar fix system, make up each frame three-dimensional image, obtain the final three-dimensional image of target.

Fig. 3 is the motion Texas tower imaging geometry figure of the embodiment of the invention.Coordinate system definition wherein is identical with Fig. 2.As shown in Figure 3, because the position of Texas tower changes in time, the radar beam sight line is pointed to target all the time simultaneously, causes radar fix system also to change in time.As shown in Figure 3, in the frame of three sampling instants, three different radar fix systems are arranged.Therefore, the target three-dimensional image that is obtained by each frame high resolution range profile can not directly make up under radar fix system, therefore, first each frame three-dimensional image is passed through coordinate conversion, be transformed under the fixed reference frame OXYZ, and then make up, obtain final three-dimensional image.

Aforesaid broadband monopulse radar three-D imaging method, Texas tower for motion, behind the three-dimensional image that obtains under the radar fix system of target in different sampling instants, the three-dimensional image of target under radar fix system corresponding to each frame is transformed under the unified reference frame, specifically can comprises:

By coordinate translation and rotational transform, with the three-dimensional image of target under radar fix system corresponding to each frame, according to the SAR geometric relationship, be transformed into respectively under the reference frame OXYZ, the transformational relation formula is:

$\left[\begin{array}{c}{X}_k\left(t_i\right)\\ Y_k\left(t_i\right)\\ Z_k\left(t_i\right)\end{array}\right]=\mathrm{\Λ}\left(t_i\right)\·\left[\begin{array}{c}{x}_{\mathrm{rk}}\left(t_i\right)\\ y_{\mathrm{rk}}\left(t_i\right)\\ z_{\mathrm{rk}}\left(t_i\right)\end{array}\right]-\left[\begin{array}{c}{X}_R\left(t_i\right)\\ Y_R\left(t_i\right)\\ Z_R\left(t_i\right)\end{array}\right]$

Wherein, t _i=iT/N(1≤i≤N, N are the sampled point number) be the sampling instant of target i frame, T is the synthetic aperture time, [x _Rk(t _i), y _Rk(t _i), z _Rk(t _i)] be the coordinate of k scattering center under radar fix system of target i frame three-dimensional image, Λ (t _i) the rotation of coordinate matrix that adopts when being the i frame, [X _R(t _i), Y _R(t _i), Z _R(t _i)] be the constantly coordinate of Texas tower under reference frame of i frame sampling.

In monopulse three-dimensional imaging processing procedure, need to carry out signal to each frame echoed signal of each scattering center of target and process, wherein, sampled point number N is not more than the maximum sampling number of radar in the synthetic aperture time T.By above-mentioned coordinate transformation relation formula, the coordinate conversion of each frame signal under different radar fixs are of each scattering center of target can be arrived under the unified coordinate system.

In concrete the application, can according to the imaging requirements of target, select suitable sampled point number.For fixing Texas tower, because the coordinate of Texas tower in reference frame do not change in time, therefore can not carry out coordinate conversion, directly the three-dimensional image of target under radar fix system corresponding to each frame be made up, obtain the final three-dimensional image of target.

In the present embodiment, Texas tower for motion, by utilizing the SAR geometric relationship, the three-dimensional image of target under radar fix system corresponding to each frame is transformed under the unified reference frame, again the three-dimensional image of each frame of target made up, both realize the three-dimensional imaging of target, and avoided again a large amount of signals to process computing, improved the efficient that the monopulse radar three-dimensional imaging is processed.

For the Texas tower of motion, aforesaid target three-dimensional imaging, wherein, in the i frame sampling moment, the coordinate of Texas tower under reference frame is:

Z _R(t _i)=H

With reference to Fig. 3, wherein, H is the height of Texas tower, and the synthetic aperture center constantly angle of squint of radar beam is

The downwards angle of visibility of radar beam is θ, and the speed of a ship or plane of carrier of radar is V, and the oblique distance of synthetic aperture center moment Texas tower and target is R ₀

Aforesaid target three-D imaging method, wherein, described rotation of coordinate matrix is:

$\mathrm{\Λ}\left(t_i\right)=\left(\begin{array}{ccc}\cos \left({\mathrm{\α}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\α}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\α}}_3\left(t_i\right)\right)\\ \cos \left({\mathrm{\β}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\β}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\β}}_3\left(t_i\right)\right)\\ \cos \left({\mathrm{\γ}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\γ}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\γ}}_3\left(t_i\right)\right)\end{array}\right)$

Wherein, α ₁(t _i), α ₂(t _i) and α ₃(t _i) represent respectively the o of the sampling instant radar fix system of target i frame _rx _rThe angle of the OX of axle and reference frame, OY and OZ axle, β ₁(t _i), β ₂(t _i) and β ₃(t _i) o of expression radar fix system _ry _rThe angle of the OX of axle and reference frame, OY and OZ axle, γ ₁(t _i), γ ₂(t _i) and γ ₃(t _i) o of expression radar fix system _rz _rThe angle of the OX of axle and reference frame, OY and OZ axle.

Fig. 4 is the Ship Target scattering point illustraton of model that the embodiment of the invention was suitable for, and based on above-mentioned target three-D imaging method, below in conjunction with Fig. 5, provides the embodiment that obtains the three-dimensional imaging figure of Ship Target scattering point model shown in Figure 4 by the Texas tower of motion.

Fig. 5 is the process flow diagram of broadband monopulse radar three-D imaging method embodiment two of the present invention.As shown in Figure 5, the method for the present embodiment comprises:

S501, radar receive from the broadband monopulse radar echoed signal that Ship Target returns;

In the present embodiment, more true to nature in order to make target echo, the radar echo signal modeling of Ship Target has also been introduced six-freedom motion model and the Multipath scattering model of certain type battleship under the high sea condition.

S502, from radar echo signal, choose 3 frame pulse signals, obtain the three-dimensional image of target under the radar fix system of 3 different sampling instants;

Concrete, from radar echo signal, choose and be respectively the T/3 moment, the 2T/3 moment, T 3 frame pulse signals constantly, T is the synthetic aperture time, carry out respectively process of pulse-compression, obtain target at these 3 different high resolution range profiles constantly, and then respectively this 3 frame high resolution range profile is carried out the three-dimensional imaging of target, obtain the three-dimensional image of target under the radar fix system of these 3 different sampling instants.

Fig. 6 ~ Figure 11 is the monopulse radar three-dimensional imaging figure of the Ship Target scattering point model among Fig. 5.Wherein, Fig. 6, Fig. 7, the three-dimensional image of the corresponding target of Fig. 8 difference under the T/3 moment, the 2T/3 moment, T radar fix system constantly.

S503, by the three-dimensional image of target under the radar fix of these 3 different sampling instants system, the three-dimensional image of synthetic target.

Concrete, first the three-dimensional image of target under the radar fix system of these 3 different sampling instants is transformed under the unified reference frame, then make up with reference to the three-dimensional image under the coordinate system, obtain the three-dimensional image of target, as shown in Figure 9.

Be the technique effect of the outstanding embodiment of the invention, the below provides the contrast figure that processes by range-aligned and phase compensation.Figure 10 be in the present embodiment radar echo signal according to the range-aligned algorithm to carrying out the target two-dimensional imaging figure that obtains after range-aligned is processed with channel signal and poor channel signal, as shown in Figure 10, because the motion state of target complexity is not difficult to obtain clearly ISAR picture of target in the situation that carry out meticulous phase compensation.The target three-dimensional image of Figure 11 for carrying out based on Figure 10 obtaining after range-aligned accurately and the meticulous motion compensation, as shown in Figure 11, when there is compound movement in Ship Target, be difficult to obtain clearly ISAR picture of target, and the ISAR picture that three-dimensional image is easily blured is further played up.

Fig. 9 and Figure 11 are contrasted as can be known, can not obtain clear ISAR as the time, the technical scheme that the embodiment of the invention provides, its imaging effect has been better than the target three-dimensional image that obtains through range-aligned and motion compensation process, and the technical scheme of the embodiment of the invention does not need to carry out complicated SAR and ISAR processing after the multiframe sampled signal is carried out process of pulse-compression, therefore, has good real-time.

It should be noted that at last: above each embodiment is not intended to limit only in order to technical scheme of the present invention to be described; Although with reference to aforementioned each embodiment the present invention is had been described in detail, those of ordinary skill in the art is to be understood that: it still can be made amendment to the technical scheme that aforementioned each embodiment puts down in writing, and perhaps some or all of technical characterictic wherein is equal to replacement; And these modifications or replacement do not make the essence of appropriate technical solution break away from the scope of various embodiments of the present invention technical scheme.

Claims (5)

1. a broadband monopulse radar three-D imaging method is characterized in that, comprising:

Receive from the broadband monopulse radar with passage echoed signal and poor passage echoed signal, choose respectively target at the pulse signal of the different sampling instants of multiframe;

Respectively every frame pulse signal is carried out process of pulse-compression, to obtain the high resolution range profile of the different sampling instants of target;

Respectively every frame high resolution range profile is carried out the monopulse three-dimensional imaging of target, obtain the three-dimensional image of target under the radar fix system of different sampling instants;

With the three-dimensional image of target under radar fix system corresponding to each frame, be transformed under the unified reference frame;

Three-dimensional image to each frame of target makes up, and forms the final three-dimensional image of target.

2. method according to claim 1 is characterized in that, corresponding radar fix is identical or not identical under the different sampling instants of each frame.

3. method according to claim 1 is characterized in that, described the three-dimensional image of target under radar fix corresponding to each frame system is transformed under the unified reference frame, comprising:

By coordinate translation and rotational transform, the three-dimensional image of target under radar fix system corresponding to each frame is transformed into respectively under the reference frame OXYZ, the transformational relation formula is:

$\left[\begin{array}{c}{X}_k\left(t_i\right)\\ Y_k\left(t_i\right)\\ Z_k\left(t_i\right)\end{array}\right]=\mathrm{\Λ}\left(t_i\right)\·\left[\begin{array}{c}{x}_{\mathrm{rk}}\left(t_i\right)\\ y_{\mathrm{rk}}\left(t_i\right)\\ z_{\mathrm{rk}}\left(t_i\right)\end{array}\right]-\left[\begin{array}{c}{X}_R\left(t_i\right)\\ Y_R\left(t_i\right)\\ Z_R\left(t_i\right)\end{array}\right]$

Wherein, t _i=iT/N(1≤i≤N, N are the sampled point number) be the sampling instant of target i frame, T is the synthetic aperture time, [x _Rk(t _i), y _Rk(t _i), z _Rk(t _i)] be the coordinate of k scattering center under radar fix system of target i frame three-dimensional image, Λ (t _i) the rotation of coordinate matrix that adopts when being the i frame, [X _R(t _i), Y _R(t _i), Z _R(t _i)] be the constantly coordinate of Texas tower under reference frame of i frame sampling.

4. method according to claim 3 is characterized in that, the i frame sampling constantly coordinate of described Texas tower under reference frame is:

Z _R(t _i)=H

Wherein, H is the height of Texas tower, and the synthetic aperture center constantly angle of squint of radar beam is The downwards angle of visibility of radar beam is θ, and the speed of a ship or plane of carrier of radar is V, and the oblique distance of synthetic aperture center moment Texas tower and target is R ₀

5. method according to claim 4 is characterized in that, described rotation of coordinate matrix is:

$\mathrm{\Λ}\left(t_i\right)=\left(\begin{array}{ccc}\cos \left({\mathrm{\α}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\α}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\α}}_3\left(t_i\right)\right)\\ \cos \left({\mathrm{\β}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\β}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\β}}_3\left(t_i\right)\right)\\ \cos \left({\mathrm{\γ}}_1\left(t_i\right)\right)& \cos \left({\mathrm{\γ}}_2\left(t_i\right)\right)& \cos \left({\mathrm{\γ}}_3\left(t_i\right)\right)\end{array}\right)$

Wherein, α ₁(t _i), α ₂(t _i) and α ₃(t _i) represent respectively the o of the sampling instant radar fix system of target i frame _rx _rThe angle of the OX of axle and reference frame, OY and OZ axle, β ₁(t _i), β ₂(t _i) and β ₃(t _i) o of expression radar fix system _ry _rThe angle of the OX of axle and reference frame, OY and OZ axle, γ ₁(t _i), γ ₂(t _i) and γ ₃(t _i) o of expression radar fix system _rz _rThe angle of the OX of axle and reference frame, OY and OZ axle.

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