CN110954899B - Sea surface ship target imaging method and device under high sea condition - Google Patents
Sea surface ship target imaging method and device under high sea condition Download PDFInfo
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Abstract
The invention discloses a sea surface ship target imaging method and device under a high sea condition, and relates to the technical field of airborne radar imaging. The method comprises the following steps: correcting according to the inertial navigation information pair, and converting the original echo signal into a distance-time domain; then, carrying out time-frequency transformation to convert the echo signals in the distance-time domain into the distance-time-frequency domain; carrying out radon transformation, solving the acceleration of the irregular motion of the sea surface ship target, and carrying out compensation of a high-order phase according to the acceleration; and carrying out Fourier analysis of the azimuth direction to obtain an imaging result of the sea surface ship target. The invention is suitable for airborne radar imaging, overcomes the problem of 'resolution blurring' when imaging a ship target on the sea surface under a high sea condition, realizes high-resolution imaging of the ship target, does not need to improve the hardware of the existing radar equipment, and has good engineering application prospect.
Description
Technical Field
The invention relates to the technical field of airborne radar imaging, in particular to a SAR/ISAR hybrid imaging method and device for sea surface ship targets under high sea conditions.
Background
Inverse Synthetic Aperture Radar (ISAR) forms a Synthetic Aperture by the relative motion of a moving object with respect to the Radar for high resolution imaging. However, the imaging quality of the airborne platform is low when the airborne platform directly images the ship target, which is mainly because the airborne motion platform images the sea surface ship target, which has both SAR and ISAR components, if there is no fine motion compensation, the ship target is directly imaged and defocused, especially under high sea conditions, the irregular motion of the ship target is further aggravated, resulting in the problem of "resolution blurring" when the sea surface ship target is imaged under high sea conditions.
Disclosure of Invention
The invention aims to solve the technical problem of providing a SAR/ISAR hybrid imaging method, a storage medium and a device for a sea surface ship target under a high sea condition aiming at the defects of the prior art.
The technical scheme for solving the technical problems is as follows:
a method for imaging sea surface ship targets under high sea conditions comprises the following steps:
acquiring inertial navigation information, and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the inertial navigation information;
acquiring an original echo signal of a sea surface ship target, correcting the original echo signal according to the first distance walk correction factor, then converting the corrected original echo signal into a distance-time domain, and performing phase compensation on the echo signal of the distance-time domain according to the phase error compensation factor;
constructing a second distance walking correction factor and a distance direction pulse compression factor according to the motion information of the airborne platform, and performing distance compression on the echo signal after phase compensation according to the second distance walking correction factor and the pulse compression factor;
constructing a distance bending correction factor according to the motion information of the airborne platform, and performing distance bending correction on the echo signals after distance compression according to the distance bending correction factor;
performing time-frequency transformation on the echo signals after the range curvature correction, and converting the echo signals in a range-time domain into a range-time-frequency domain;
selecting a distance unit with the largest energy according to the echo signals of the distance-time-frequency domain to carry out Radon transformation according to a preset angle interval, searching the position of a peak point on a Radon parameter plane, and solving an angle offset corresponding to the position of the peak point;
solving the acceleration of the irregular movement of the sea surface ship target according to the angle offset, constructing an acceleration compensation factor according to the acceleration, and performing high-order phase compensation on the echo signal after the distance bending correction in a frequency domain according to the acceleration compensation factor;
and carrying out azimuth Fourier analysis on the echo signal subjected to the high-order phase compensation to obtain an imaging result of the sea surface ship target.
The invention has the beneficial effects that: according to the imaging method provided by the invention, the non-ideal motion of the airborne platform is compensated through inertial navigation information, the non-regular motion of the sea surface ship target is compensated through refined parameter estimation, and finally SAR/ISAR hybrid imaging is carried out, so that the problem of 'resolution blurring' when the sea surface ship target is subjected to ISAR imaging under a high sea condition is solved, and high-resolution imaging of the ship target is realized.
Another technical solution of the present invention for solving the above technical problems is as follows:
a storage medium having stored therein instructions, which when read by a computer, cause the computer to execute the method of imaging a marine vessel target on the sea surface under high sea conditions as described in the above technical solution.
Another technical solution of the present invention for solving the above technical problems is as follows:
a sea surface ship target imaging device under high sea conditions comprises:
a memory for storing a computer program;
and the processor is used for executing the computer program to realize the imaging method of the sea surface ship target under the high sea condition.
Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a schematic flow chart diagram provided by an embodiment of the imaging method of the present invention;
FIG. 2 is a diagram illustrating a real-time imaging result of a ship target on the sea surface by a conventional imaging method;
FIG. 3 is a schematic diagram of a real-time imaging result of a sea surface ship target provided by an embodiment of the imaging method of the present invention;
FIG. 4 is a schematic diagram of a radar detection scene provided by another embodiment of the imaging method of the present invention;
fig. 5 is a structural frame diagram provided by an embodiment of an image forming apparatus of the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
As shown in fig. 1, a schematic flow chart is provided for an embodiment of the imaging method of the present invention, the method for imaging a sea surface ship target under high sea conditions is a SAR/ISAR hybrid imaging, including:
s1, acquiring inertial navigation information, and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the inertial navigation information;
it should be noted that the inertial navigation information may be obtained by detecting a detection device of the airborne platform, and includes motion vectors of the motion platform along various directions, an included angle between the motion platform and the due north direction, and the like. The course direction error can be deduced through inertial navigation information, and then a first distance walking correction factor and a phase error compensation factor are obtained.
It should be understood that the airborne platform may be an aircraft, such as an airplane, a drone, or the like.
S2, acquiring an original echo signal of a sea surface ship target, correcting the original echo signal according to a first distance walk correction factor, then converting the corrected original echo signal into a distance-time domain, and performing phase compensation on the echo signal of the distance-time domain according to a phase error compensation factor;
preferably, the original echo signal may be subjected to distance-dimensional FFT, then multiplied by the first distance walk correction factor, and then subjected to distance-dimensional IFFT, converted to the distance time domain to obtain the correction result, and then directly multiplied by the phase error compensation factor to perform phase compensation, for example:
e1(τ,tm)＝IFFT[FFT(e0(τ,tm))·H01]
wherein FFT (-) and IFFT (-) denote distance-dimensional FFT and distance-dimensional IFFT, respectively, e0(τ,tm) Representing the original echo signal, τ being the fast time, tm＝mTrIndicating slow time, TrFor a pulse repetition period, H01A first distance walk correction factor.
Then, the result e after the non-ideal movement of the carrier is corrected1(τ,tm) Performing phase compensation, namely:
e2(τ,tm)＝e1(τ,tm)·H02
wherein e is2(τ,tm) For the phase-compensated echo signal, H02Is a phase error compensation factor.
S3, constructing a second distance walking correction factor and a distance direction pulse compression factor according to the motion information of the airborne platform, and performing distance compression on the echo signal after phase compensation according to the second distance walking correction factor and the pulse compression factor;
it should be noted that the second range walk correction factor is a range walk correction performed to reduce a phenomenon that a target spans from a unit walk due to the motion of the radar platform.
Preferably, after FFT transformation is performed on the phase-compensated echo signal, the phase-compensated echo signal is multiplied by the second distance walk correction factor and the pulse compression factor in the distance direction, and then IFFT transformation is performed to complete distance correction and distance compression, for example:
e3(τ,tm)＝IFFT[FFT(e2(τ,tm))·H11·H12]
wherein e is3(τ,tm) Representing the echo signal in the range-time domain after range compression, H11For a second distance walk correction factor, H12Is the pulse compression factor in the range direction.
S4, constructing a distance bending correction factor according to the motion information of the airborne platform, and performing distance bending correction on the echo signal after distance compression according to the distance bending correction factor;
preferably, the distance-compressed echo signal may be subjected to two-dimensional FFT in the distance dimension and the azimuth dimension, then multiplied by the distance warping correction factor, and then subjected to two-dimensional IFFT in the distance dimension and the azimuth dimension, to complete the distance warping correction, for example:
s(τ,tm)＝IFFT2[FFT2(e3(τ,tm))·H2]
wherein, s (τ, t)m) After the distance bending correction is expressedThe FFT2 (-) represents a two-dimensional FFT in the range and azimuth dimensions, and the IFFT2 (-) represents a two-dimensional IFFT in the range and azimuth dimensions.
S5, carrying out time-frequency transformation on the echo signals after the range curvature correction, and converting the echo signals in a range-time domain into a range-time-frequency domain;
preferably, the echo signals in the range-time domain can be converted into the range-time-frequency domain using a Cohen-like time-frequency distribution transform.
S6, selecting a distance unit with the largest energy according to the echo signal of the distance-time-frequency domain to carry out Radon transformation according to a preset angle interval, searching the position of a peak point on a Radon parameter plane, and solving the angle offset corresponding to the position of the peak point;
it should be noted that the preset angle interval may be set according to actual requirements, and may be, for example, 0.1 °.
The formula for the radon transform is defined as:
where C (τ, t, f) represents the echo data in the range-time-frequency domain after time-frequency transformation.
S7, solving the acceleration of the irregular movement of the sea surface ship target according to the angle offset, constructing an acceleration compensation factor according to the acceleration, and performing high-order phase compensation on the echo signal after the distance bending correction in a frequency domain according to the acceleration compensation factor;
preferably, the acceleration may be obtained by a normalized frequency formula of the chirp signal corresponding to the angular offset and a normalized frequency formula caused by the acceleration in a simultaneous manner.
For example, assume that the radian measure corresponding to the peak obtained by the search is θ0Then theta0The normalized frequency of the corresponding chirp signal may be expressed as
Wherein N is the number of pulses, TrIs a pulse repetition period. Meanwhile, the normalized frequency modulation due to acceleration can be written as:
by simultaneously solving the two frequency modulation rate-related formulas in step six, the acceleration can be found as:
preferably, the echo signal after the range curvature correction may be subjected to FFT, multiplied by an acceleration compensation factor, and then subjected to IFFT to complete compensation of the higher order phase, for example:
s1(τ,tm)＝IFFT[FFT(s(τ,tm))·H2]
wherein H3Representing an acceleration compensation factor.
And S8, performing azimuth Fourier analysis on the echo signal after the high-order phase compensation to obtain an imaging result of the sea surface ship target.
Preferably, the FFT of the echo signal after the higher-order phase compensation may be performed to obtain an imaging result, for example:
s2(τ,fa)＝FFT(s1(τ,tm))
wherein s is2(τ,fa) Is the ISAR imaging result of the ship target.
It should be noted that, in order to implement the above imaging method, an imaging system may be established in advance, and for example, the imaging system may include: the device comprises an inertial navigation compensation module, a range migration correction and pulse pressure module, a time-frequency transformation module, a Radon transformation module, a peak search module, a high-order phase compensation factor construction module and an azimuth Doppler analysis module.
The inertial navigation compensation module can be used for compensating the error of the motion platform according to the inertial navigation information;
the range migration correction and pulse pressure module can be used for performing range migration correction and range pulse pressure on the echo signal;
the time-frequency transformation module can be used for performing time-frequency transformation on the data after the distance pulse pressure and converting the distance-time domain data into a distance-time-frequency domain;
the Radon conversion module can be used for selecting a distance unit with larger energy to perform Radon conversion according to a certain angle interval;
the peak value searching module can be used for searching the position of a peak value point on a Radon parameter plane and solving the corresponding angle offset;
the high-order phase compensation factor construction module can be used for solving the acceleration of the irregular movement of the ship according to the solved angle offset, so that a high-order phase compensation factor is further constructed;
the azimuth Doppler analysis module can be used for compensating the high-order phase of the echo signal in a frequency domain by using the obtained high-order phase compensation factor, and finally carrying out azimuth Fourier analysis to obtain an ISAR imaging result of the ship target
In order to illustrate the effect of the invention, according to the technical scheme of the invention, simulation verification is carried out, and the simulation experiment environment is MATLAB R2015a, Intel (R) Xeon (R)2CPU E5-2630V 4@2.2GHz and Window 7 flagship edition.
The technical scheme of the invention is used for imaging a ship target on the sea surface under a simulation environment by using echo data acquired by an airborne radar to obtain an ISAR imaging result of the ship target on the sea surface, wherein FIG. 2 is an imaging result of a traditional imaging scheme, and FIG. 3 is an imaging result of the scheme of the invention.
As can be seen from fig. 2 and 3, compared with the conventional method, the imaging result of the sea surface ship target in the imaging result of the present invention is clearer, and clearly shows the contour of the ship, whereas the conventional imaging method has a transverse blur due to the shaking of the ship, the movement of the airborne platform, and the like.
According to the imaging method provided by the embodiment, the non-ideal motion of the airborne platform is compensated through inertial navigation information, the non-regular motion of the sea surface ship target is compensated through refined parameter estimation, and finally SAR/ISAR hybrid imaging is carried out, so that the problem of 'resolution blurring' when the sea surface ship target is subjected to ISAR imaging under a high sea condition is solved, high-resolution imaging of the ship target is realized, meanwhile, hardware improvement on the existing radar equipment is not required, and the imaging method has a good engineering application prospect.
As shown in fig. 4, an exemplary radar detection scene schematic diagram is provided, where the airborne platform is an airplane, an O-XYZ spatial rectangular coordinate system is established with the airborne platform as a center, the airplane flies at a speed v along a certain direction, an included angle between the flight direction and the due north direction is α, the flight altitude is H, and if there is a sea surface ship target to be detected on the sea surface, an O '-X space coordinate system is established with the ship as a center, and an O' -XYZ spatial rectangular coordinate system is established with the ship as a centerbYbZbA rectangular space coordinate system, the ship moves at a speed V along a certain direction, and the linear distance between the airplane and the ship is RsI.e. the center-to-center distance of the scene, and the downward viewing angle is beta. The aircraft transmits probe waves to a sea surface ship target at a certain frequency to acquire echo signals, and some optional embodiments of the invention are described below with reference to fig. 4.
Optionally, in some embodiments, acquiring inertial navigation information, and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the inertial navigation information specifically includes:
acquiring inertial navigation information, and solving a vertical route direction error and a vertical route direction error according to the inertial navigation information;
solving the motion error along the beam sight direction caused by the non-ideal motion of the airborne platform according to the vertical course direction error and the vertical course direction error;
and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the motion error.
According to the embodiment, the non-ideal motion of the airborne platform is compensated through inertial navigation information, and the imaging precision can be improved.
Optionally, in some embodiments, the vertical course direction error Δ y and the vertical course direction error Δ z are calculated according to the following formulas:
wherein v isNVelocity vector, v, of airborne platform in due northEVelocity vector, v, of airborne platform in the east-ward directionDRepresents a motion velocity vector along the vertical downward direction, alpha is the included angle of the airborne platform and the due north direction,
which is indicative of the operation of the integration,
denotes the averaging operation, tm＝mTrDenotes slow time, m denotes an integer, TrIs a pulse repetition period;
the motion error Δ r is calculated according to the following equation:
Δr＝Δzcosβ+Δysinβ
wherein, beta represents the following visual angle, and the calculation formula is as follows:
wherein H represents the height of the motion platform, RsThe scene center distance is obtained;
calculating a first distance walk correction factor H according to the following formula01And a phase error compensation factor H02：
Wherein τ is the fast time, λ is the radar wavelength, c is the speed of light, frIs a distance frequency with a value range of
FsIs the sampling frequency.
Optionally, in some embodiments, the second distance walk correction factor H is calculated according to the following formula11And the pulse compression factor H of the distance direction12：
Wherein, Δ R (t)m)≈-vsin(θ0)tmV is the speed of the airborne platform, θ0Is the angle f between the line of sight of the radar beam and the normal direction of the movement direction of the airborne platformrIs a distance frequency with a value range of
FsIs the sampling frequency, tm＝mTrDenotes slow time, m denotes an integer, TrIs the pulse repetition period, c is the speed of light, KrThe azimuth frequency modulation rate is a distance direction.
Optionally, in some embodiments, the range curvature correction factor H is calculated according to the following formula2：
Wherein R issIs the center distance of the scene, faIs the Doppler frequency, and has a value range of
farIs the pulse repetition frequency, frIs a distance frequency with a value range of
FsFor the sampling frequency, v is the speed of the airborne platform, λ is the radar wavelength, and c is the speed of light.
Optionally, in some embodiments, the range-curvature corrected echo signal is time-frequency transformed according to the following formula:
wherein, s (τ, t)m) The echo signal after the range curvature correction is represented, s (·) represents the conjugation operation, u, x, v, t, f represents the time-frequency transform parameter C (tau, t, f) represents the echo signal in the range-time-frequency domain after the time-frequency transform, and phi (x, v) is a kernel function.
It should be understood that Cohen can be considered as a smoothed WVD distribution, and when Φ (x-t) ═ 1, it is the WVD distribution. When the kernel function is exponentially distributed, it is a CW distribution.
Optionally, in some embodiments, the acceleration is calculated according to the following formula
Wherein, theta0Is the angle offset corresponding to the position of the peak point, N is the number of pulses, TrFor the pulse repetition period, frIs distance frequency, c is speed of light, fcRepresenting the carrier frequency.
Optionally, inIn some embodiments, the acceleration compensation factor H is calculated according to the following equation3：
Wherein, tm＝mTrDenotes slow time, m denotes an integer, TrFor the pulse repetition period, f denotes the frequency of the echo signal in the range-time-frequency domain after time-frequency transformation.
It is understood that some or all of the alternative embodiments described above may be included in some embodiments.
In other embodiments of the present invention, there is also provided a storage medium having stored therein instructions that, when read by a computer, cause the computer to execute the method for imaging a sea surface ship object under high sea conditions as described in any of the above embodiments.
In another embodiment of the present invention, as shown in fig. 5, there is also provided a sea surface vessel target imaging device under high sea conditions, comprising:
a memory 1 for storing a computer program;
a processor 2 for executing a computer program for implementing the method for imaging a ship target on the sea surface under high sea conditions as described in any of the above embodiments.
It should be noted that the above embodiments are product embodiments corresponding to the previous method embodiments, and for optional implementation and descriptions of the product embodiments, reference may be made to corresponding implementation and descriptions in the above method embodiments, which are not described herein again.
The reader should understand that in the description of this specification, reference to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described method embodiments are merely illustrative, and for example, the division of steps into only one logical functional division may be implemented in practice in another way, for example, multiple steps may be combined or integrated into another step, or some features may be omitted, or not implemented.
The above method, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention essentially or partially contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. A method for imaging a ship target on the sea surface under high sea conditions, comprising:
acquiring inertial navigation information, and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the inertial navigation information;
acquiring an original echo signal of a sea surface ship target, correcting the original echo signal according to the first distance walk correction factor, then converting the corrected original echo signal into a distance-time domain, and performing phase compensation on the echo signal of the distance-time domain according to the phase error compensation factor;
constructing a second distance walking correction factor and a distance direction pulse compression factor according to the motion information of the airborne platform, and performing distance compression on the echo signal after phase compensation according to the second distance walking correction factor and the pulse compression factor;
constructing a distance bending correction factor according to the motion information of the airborne platform, and performing distance bending correction on the echo signals after distance compression according to the distance bending correction factor;
performing time-frequency transformation on the echo signals after the range curvature correction, and converting the echo signals in a range-time domain into a range-time-frequency domain;
selecting a distance unit with the largest energy according to the echo signals of the distance-time-frequency domain to carry out Radon transformation according to a preset angle interval, searching the position of a peak point on a Radon parameter plane, and solving an angle offset corresponding to the position of the peak point;
solving the acceleration of the irregular movement of the sea surface ship target according to the angle offset, constructing an acceleration compensation factor according to the acceleration, performing high-order phase compensation on the echo signal after the distance bending correction in a frequency domain according to the acceleration compensation factor, and calculating the acceleration according to the following formula
Wherein, theta0Is the angle offset corresponding to the position of the peak point, N is the number of pulses, TrFor the pulse repetition period, frIs distance frequency, c is speed of light, fcRepresents a carrier frequency;
and carrying out azimuth Fourier analysis on the echo signal subjected to the high-order phase compensation to obtain an imaging result of the sea surface ship target.
2. The method according to claim 1, wherein acquiring inertial navigation information, and constructing a first distance walk correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the inertial navigation information, specifically comprises:
acquiring inertial navigation information, and solving a vertical route direction error and a vertical route direction error according to the inertial navigation information;
obtaining a movement error along the beam sight direction caused by the non-ideal movement of the airborne platform according to the vertical course direction error and the vertical course direction error;
and constructing a first distance walking correction factor and a phase error compensation factor corresponding to the non-ideal motion of the airborne platform according to the motion error.
3. The method of imaging a sea surface vessel target under high sea conditions of claim 2, wherein the vertical course direction error Δ y and the vertical course direction error Δ z are calculated according to the following formulas:
wherein v isNVelocity vector, v, of airborne platform in due northEVelocity vector, v, of airborne platform in the east-ward directionDRepresents a motion velocity vector along the vertical downward direction, alpha is the included angle of the airborne platform and the due north direction,
which is indicative of the operation of the integration,
denotes the averaging operation, tm＝mTrDenotes slow time, m denotes an integer, TrIs a pulse repetition period;
the motion error Δ r is calculated according to the following equation:
Δr＝Δzcosβ+Δysinβ
wherein, beta represents the following visual angle, and the calculation formula is as follows:
wherein H represents the height of the motion platform, RsThe scene center distance is obtained;
calculating the first distance walk correction factor H according to the following formula01And the phase error compensation factor H02：
Wherein τ is the fast time, λ is the radar wavelength, c is the speed of light, frIs a distance frequency with a value range of
FsIs the sampling frequency.
4. The method of imaging a sea surface vessel target under high sea conditions of claim 1, wherein the second distance walk correction factor H is calculated according to the following formula11And a pulse compression factor H of said distance direction12：
Wherein, Δ R (t)m)≈-vsin(θ0)tmV is the speed of the airborne platform, θ0Is the angle f between the line of sight of the radar beam and the normal direction of the movement direction of the airborne platformrIs a distance frequency with a value range of
FsIs the sampling frequency, tm＝mTrDenotes slow time, m denotes an integer, TrIs the pulse repetition period, c is the speed of light, KrThe azimuth frequency modulation rate is a distance direction.
5. The method of imaging a sea surface vessel target under high sea conditions of claim 1, wherein the range-curvature correction factor H is calculated according to the following formula2：
Wherein R issIs the center distance of the scene, faIs the Doppler frequency, value rangeIs composed of
farIs the pulse repetition frequency, frIs a distance frequency with a value range of
FsFor the sampling frequency, v is the speed of the airborne platform, λ is the radar wavelength, and c is the speed of light.
6. The method of imaging a sea surface vessel target under high sea conditions of claim 1, wherein the echo signal after the range-curvature correction is time-frequency transformed according to the following formula:
wherein, s (τ, t)m) The echo signal after the range curvature correction is represented, s (·) represents the conjugation operation, u, x, v, t, f represents time-frequency transformation parameters, C (tau, t, f) represents the echo signal in the range-time-frequency domain after the time-frequency transformation, and phi (x, v) is a kernel function.
7. The method of imaging a sea surface vessel target under high sea conditions of claim 6, wherein the acceleration compensation factor H is calculated according to the following formula3：
Wherein, tm＝mTrDenotes slow time, m denotes an integer, TrFor the pulse repetition period, f denotes the frequency of the echo signal in the range-time-frequency domain after time-frequency transformation.
8. A storage medium having stored therein instructions which, when read by a computer, cause the computer to execute the method of imaging a sea surface vessel object under high sea conditions of any one of claims 1 to 7.
9. A sea surface ship target imaging device under high sea conditions is characterized by comprising:
a memory for storing a computer program;
a processor for executing the computer program to implement the high sea state vessel object imaging method of any one of claims 1 to 7.
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