CN106324597B - The translational compensation and imaging method of big corner ISAR radar based on PFA - Google Patents
The translational compensation and imaging method of big corner ISAR radar based on PFA Download PDFInfo
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- CN106324597B CN106324597B CN201610616196.6A CN201610616196A CN106324597B CN 106324597 B CN106324597 B CN 106324597B CN 201610616196 A CN201610616196 A CN 201610616196A CN 106324597 B CN106324597 B CN 106324597B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/904—SAR modes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/904—SAR modes
- G01S13/9064—Inverse SAR [ISAR]
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Abstract
The translational compensation and imaging method of the invention discloses a kind of big corner ISAR radar based on PFA, its main thought are as follows: ground ISAR radar emission chirp signal, and Frequency mixing processing is carried out to the target echo signal received, the base band echo-signal s (t after being mixedr,ta)；To s (tr,ta) obtain apart from pulse pressure processing apart from pulse pressure treated base band echo-signalThen rightTranslational compensation processing is carried out, translational compensation is obtained treated base band echo-signal S (fr,ta), calculate the wave-number domain base band echo-signal W (k indicated under rectangular coordinate systemy,kx), and then calculate error phase φerror(ky,kx) in apart from unrelated error phase, i.e. error phase of the distance to the wave-number domain base band echo-signal after inverse fast fourier transformAccording toObtain the target translational error with distance dependentAccording toWave-number domain base band echo-signal W after calculating phase compensationcomp(ky,kx), and then the ISAR for calculating wave-number domain base band echo-signal is imaged and carries out Autofocus processing, the ISAR imaging after obtaining Autofocus processing.
Description
Technical field
The invention belongs to Radar Signal Processing Technology field, in particular to a kind of big corner ISAR radar based on PFA
Translational compensation and imaging method, the i.e. big corner based on polar format algorithm (Polar Format Algorithm, PFA) are inverse
The translational compensation method and imaging method of synthetic aperture radar (Inverse Synthetic Radar, ISAR) radar, are suitable for
Directly carry out the ISAR imaging of sampling radar.
Background technique
Inverse Synthetic Aperture Radar can carry out bidimensional imaging to the noncooperative target of movement, to obtain more target letters
Breath, target identification and classification for after provide basis, therefore are widely paid close attention to and applied.It is continuous with Radar Technology
The acquisition of development, high resolution radar ISAR imaging has been a hot spot of research and difficulties, and the distance of ISAR imaging is to resolution
Rate is improved by increasing transmitted bandwidth, and azimuth resolution is realized by increasing the observation angle to target, but is observed
The increase of angle will lead to scattering point and occur to get over distance unit migration (Migration Through Range Cell, MTRC),
Simultaneously its corresponding Doppler cannot be approximately steady state value, if more distance unit migration is not corrected and phase mend
It repays, ISAR imaging will be in distance and bearing to defocusing.So to obtain the ISAR imaging of high quality, mesh is not only considered
The caused more distance unit migration MTRC of mark translation, it is also contemplated that the angle influence that target rotational generates, especially big corner feelings
Under condition, the strong coupling of translation component and rotative component makes translational compensation that tradition is mended based on the translation of envelope alignment and self-focusing
Compensation method is difficult accurately to correct translation component, so that the result of subsequent big corner ISAR imaging algorithm processing goes out
Existing distance and bearing to defocus.
Summary of the invention
For the deficiency of above-mentioned prior art, it is an object of the invention to propose a kind of big corner ISAR based on PFA
The translational compensation and imaging method of radar, the translational compensation and imaging method of big corner ISAR radar of this kind based on PFA pass through
PFA correction rotation causes bidimensional to couple, and can be improved the processing accuracy and efficiency of target translational compensation.
To reach above-mentioned technical purpose, the present invention is achieved by the following scheme.
A kind of translational compensation and imaging method of the big corner ISAR radar based on PFA, comprising the following steps:
Step 1, ground ISAR radar emission chirp signal, and the target echo signal received is carried out at mixing
Reason, the base band echo-signal s (t after being mixedr,ta)；Wherein, trIt indicates apart from fast time, taIndicate the orientation time；
Step 2, to the base band echo-signal s (t after mixingr,ta) obtain apart from pulse pressure processing apart from pulse pressure processing
Base band echo-signal afterwardsThen pulse pressure of adjusting the distance treated base band echo-signalIt carries out at translational compensation
Reason obtains translational compensation treated base band echo-signal S (fr,ta) and target translational error △ R (ta)；Wherein, frIndicate away from
Off-frequency rate；
Step 3, by translational compensation treated base band echo-signal S (fr,ta) wave-number domain is transformed to, obtain wave-number domain base
Band echo-signal W (kr, θ), then by polar format algorithm PFA to wave-number domain base band echo-signal W (kr, θ) and carry out interpolation
Transformation, obtains the wave-number domain base band echo-signal W (k indicated under rectangular coordinate systemy,kx), and calculate target translational error △ R
(ta) caused by error phase φerror(ky,kx), and then error phase φ is calculatederror(ky,kx) in apart from unrelated
Error phase φr_indep(ky0,kx)；
Wherein, krIndicate radial space wave number, θ indicates corner of the target relative to radar, kyIt indicates under rectangular coordinate system
Distance is to space wave number, kxIndicate the orientation space wave number under rectangular coordinate system；
Step 4, according to error phase φerror(ky,kx) in apart from unrelated error phase φr_indep(ky0,kx), meter
Calculation obtains error phase of the distance to the wave-number domain base band echo-signal after inverse fast fourier transformky0Table
Show distance to wave number center；
Step 5, according to error phase φerror(ky,kx) in apart from unrelated error phase φr_indep(ky0,kx) and away from
The error phase of wave-number domain base band echo-signal after the inverse fast fourier transform of descriscentPhase benefit is calculated
Wave-number domain base band echo-signal W after repayingcomp(ky,kx), and then calculate the ISAR imaging of wave-number domain base band echo-signal；
Step 6, Autofocus processing is carried out to the ISAR imaging of wave-number domain base band echo-signal, after obtaining Autofocus processing
ISAR is imaged, and the ISAR imaging after the Autofocus processing can be improved the image quality of ISAR imaging.
Compared with prior art, the invention has the following advantages that
The method of the present invention is corrected by more distance unit migration MTRC of the polar format algorithm PFA to space-variant, is solved
Keystone algorithm of having determined cannot adjust the distance bending the problem of being corrected；Two step compensation are carried out to target translational error simultaneously,
The influence that ISAR is imaged in target translation has been accurately compensated for, there is more big corner processing capacity and higher precision.
Detailed description of the invention
Invention is further described in detail with specific embodiment for explanation with reference to the accompanying drawing.
Fig. 1 is the translational compensation and imaging method flow chart of a kind of big corner ISAR radar based on PFA of the invention；
Fig. 2 is the target scattering point relative position schematic diagram of emulation experiment；
Fig. 3 is flight path figure of the target relative to radar；
Fig. 4 (a) is the distance of error free processing to envelope result schematic diagram；
Fig. 4 (b) is the distance that handles of the present invention to envelope result schematic diagram；
Fig. 4 (c) is the distance of conventional method processing to envelope result schematic diagram；
Fig. 5 (a) is the imaging results schematic diagram for carrying out translational error and accurately compensating；
Fig. 5 (b) is that imaging results schematic diagram is obtained using the method for the present invention；
Fig. 5 (c) is the imaging results schematic diagram obtained using conventional method；
Fig. 6 (a) is the two-dimentional contour map of mark point 1 in the Fig. 2 for carry out the accurate compensation deals of translational error；
Fig. 6 (b) is the two-dimentional contour map of mark point 1 in Fig. 2 of conventional method processing；
Fig. 6 (c) is the two-dimentional contour map of mark point 1 in Fig. 2 of the method for the present invention processing；
Fig. 6 (d) is accurately the compensating in translational error respectively of mark point 1 in Fig. 2, conventional method processing and the method for the present invention
The comparative result schematic diagram of the orientation sectional view obtained under disposition；
Fig. 7 (a) is the two-dimentional contour map of mark point 2 in the Fig. 2 for carry out the accurate compensation deals of translational error；
Fig. 7 (b) is the two-dimentional contour map of mark point 2 in Fig. 2 of conventional method processing；
Fig. 7 (c) is the two-dimentional contour map of mark point 2 in Fig. 2 of the method for the present invention processing；
Fig. 7 (d) is that mark point 2 accurately compensates, at conventional method processing and the method for the present invention in translational error respectively in Fig. 2
The comparative result schematic diagram of the orientation sectional view obtained in the case of reason；
Fig. 8 (a) is the two-dimentional contour map of mark point 3 in Fig. 2 of the accurate compensation deals of translational error；
Fig. 8 (b) is the two-dimentional contour map of mark point 3 in Fig. 2 of conventional method processing；
Fig. 8 (c) is the two-dimentional contour map of mark point 3 in Fig. 2 of the method for the present invention processing；
Fig. 8 (d) is that mark point 3 accurately compensates, at conventional method processing and the method for the present invention in translational error respectively in Fig. 2
The comparative result schematic diagram of the orientation sectional view obtained in the case of reason；
Fig. 9 (a) is the two-dimentional contour map of mark point 4 in Fig. 2 of the accurate compensation deals of translational error；
Fig. 9 (b) is the two-dimentional contour map of mark point 4 in Fig. 2 of conventional method processing
Fig. 9 (c) is the two-dimentional contour map of mark point 4 in Fig. 2 of the method for the present invention processing；
Fig. 9 (d) is that mark point 4 accurately compensates, at conventional method processing and the method for the present invention in translational error respectively in Fig. 2
The comparative result schematic diagram of the orientation sectional view obtained in the case of reason.
Specific embodiment
It referring to Fig.1, is the translational compensation and imaging method process of a kind of big corner ISAR radar based on PFA of the invention
Figure；The translational compensation and imaging method of the big corner ISAR radar based on PFA, comprising the following steps:
Step 1, ground ISAR radar emission chirp signal, and the target echo signal received is carried out at mixing
Reason, the base band echo-signal s (t after being mixedr,ta)；Wherein, trIt indicates apart from fast time, taIndicate the orientation time.
Specifically, the base band echo-signal s (t after the mixingr,ta) expression formula are as follows:
Wherein, trIt indicates apart from fast time, taIndicate orientation time, ar(t) the base band echo-signal s after mixing is indicated
(tr,ta) distance to window function,TpIndicate the pulse width of chirp signal, γ indicates frequency modulation on pulse
The frequency modulation rate of signal, c indicate that the light velocity, t indicate time variable, and λ indicates the wavelength of chirp signal；R(ta) indicate that target arrives
The oblique distance course of the target to radar is configured to multinomial model, expression formula by the oblique distance course of radar are as follows:R0Indicate target rotation center to radar initial distance,
V indicates radial velocity of the target with respect to radar, and a indicates radial acceleration of the target with respect to radar, Rn(ta) indicate n rank or more
High-order translation component, n > 2；(x, y) indicates the initial position relative to target rotation center of target scattering point, and θ indicates target
Relative to the corner of radar, it is big corner that target, which is [8,12] relative to the rotational angle theta of radar,；Exp indicates exponential function.
Step 2, to the base band echo-signal s (t after mixingr,ta) obtain apart from pulse pressure processing apart from pulse pressure processing
Base band echo-signal afterwardsThen pulse pressure of adjusting the distance treated base band echo-signalIt carries out at translational compensation
Reason obtains translational compensation treated base band echo-signal S (fr,ta) and target translational error △ R (ta)。
Specifically, described apart from pulse pressure treated base band echo-signalExpression formula are as follows:
Wherein, ApIt indicates apart from pulse pressure treated base band echo-signalAmplitude, B indicate apart from pulse pressure processing
Base band echo-signal afterwardsBandwidth, sinc () indicate sinc function, trIt indicates apart from fast time, R (ta) indicate mesh
The oblique distance course of radar is marked, c indicates that the light velocity, λ indicate that the wavelength of chirp signal, exp indicate exponential function.
Pulse pressure of adjusting the distance treated base band echo-signalEnvelope curve carry out fitting of a polynomial, estimate target
The speed of translationWith the translatory acceleration of targetReuse the speed of the target translationWith the translatory acceleration of target
Pulse pressure of adjusting the distance treated base band echo-signalTranslational compensation processing is carried out, translational compensation is obtained treated base band
Echo-signal S (fr,ta), expression formula are as follows:
Wherein, △ R (ta) indicate target translational error, i.e., the practical translation of target and estimation obtain target translation between
Difference,Rect indicates rectangular function, Rn(ta) indicate n rank more than high-order
Translation component, n > 2；frIndicate frequency of distance, fcIndicate carrier frequency, taIndicate the orientation time, v indicates radial direction of the target with respect to radar
Speed, a indicate radial acceleration of the target with respect to radar,Indicate the speed for the target translation that estimation obtains,Expression is estimated
The translatory acceleration of the target arrived.
Step 3, by translational compensation treated base band echo-signal S (fr,ta) wave-number domain is transformed to, obtain wave-number domain base
Band echo-signal W (kr, θ), then by polar format algorithm PFA to wave-number domain base band echo-signal W (kr, θ) and carry out interpolation
Transformation, obtains the wave-number domain base band echo-signal W (k indicated under rectangular coordinate systemy,kx), and calculate target translational error △ R
(ta) caused by error phase φerror(ky,kx), and then error phase φ is calculatederror(ky,kx) in apart from unrelated
Error phase φr_indep(ky0,kx)；Wherein, krIndicate radial space wave number, θ indicates corner of the target relative to radar, kyTable
Show distance under rectangular coordinate system to space wave number, kxIndicate the orientation space wave number under rectangular coordinate system.
Specifically, the wave-number domain base band echo-signal W (kr, θ) and expression formula are as follows:
W(kr, θ) and=P (kr)exp(-jkr(xsinθ+ycosθ))exp(-jkr△R(θ))
Wherein, krIndicate radial space wave number,P(kr) indicate wave-number domain base band echo-signal W (kr,
Distance θ) to window function,△krBIndicate radial wave SerComm degree, △ krB=max (kr)-min(kr)；
krcIndicate radial space wave number center,fcIndicate carrier frequency；Max table seeks maxima operation, and min expression is sought most
Small Value Operations.
The wave-number domain base band echo-signal W (kr, θ) and it is in polar coordinates (kr, θ) under indicate wave-number domain base band echo letter
Number, by polar format algorithm PFA in polar coordinates (kr, θ) under the wave-number domain base band echo-signal that indicates carry out interpolation change
It changes, obtains the wave-number domain base band echo-signal W (k indicated under rectangular coordinate systemy,kx), kyIndicate rectangular coordinate system under distance to
Space wave number, kxIndicate the orientation space wave number under rectangular coordinate system；The wave-number domain base band indicated under the rectangular coordinate system
Echo-signal W (ky,kx), expression formula are as follows:
Wherein, W () indicates wave-number domain base band echo-signal,krcIndicate radial space
Wave number center,fcIndicate carrier frequency；kx=krSin θ, ky=krCos θ, △ krBIndicate radial wave SerComm degree, soφerror(ky,kx) indicate target translational error △ R (ta) caused by error phase,△ R (θ) indicates target translational error △ R (ta) using rotational angle theta as independent variable when
Representation, θ indicate corner of the target relative to radar.
Then by target translational error △ R (ta) caused by error phase φerror(ky,kx) in ky=ky0Place carries out Taylor
Series expansion, and quadratic term is remained into, obtain target translational error △ R (ta) caused by error phase φerror(ky,kx)
Taylor series expansion:
Wherein, φr_indep(ky0,kx) indicate error phase φerror(ky,kx) in apart from unrelated error phase,
φr_dep(ky,kx) indicate error phase φerror(ky,kx) in error phase with distance dependent, φerror(ky,kx) indicate mesh
Mark translational error △ R (ta) caused by error phase, △ R'(arctan (kx/ky0)) indicate △ R (arctan (kx/ky)) opposite
In arctan (kx/ky) first derivative, △ R " (arctan (kx/ky0)) indicate △ R (arctan (kx/ky)) relative to
arctan(kx/ky) in ky=ky0When second dervative, △ R (arctan (kx/ky)) indicate target translational error △ R (ta) to turn
AngleRepresentation when for independent variable, ky0Distance is indicated to wave number center, while distance is to wave number center ky0
It is distance under rectangular coordinate system to space wave number kyIntermediate value；kxIndicate the orientation space wave number under rectangular coordinate system.
Step 4, according to error phase φerror(ky,kx) in apart from unrelated error phase φr_indep(ky0,kx), meter
Calculation obtains error phase of the distance to the wave-number domain base band echo-signal after inverse fast fourier transformky0Table
Show distance to wave number center.
The specific sub-step of step 4 are as follows:
The wave-number domain base band echo-signal W (k indicated under the 4.1 interception rectangular coordinate systemsy,kx) a part of wave in centre
Number field base band echo-signalDistance is obtained to the wave-number domain base band echo-signal after inverse fast fourier transformThe wave-number domain base band echo-signal W (k indicated under the interception rectangular coordinate systemy,kx) a part of wave in centre
Number field base band echo-signalIts requirement is: so that the distance is to the wave-number domain base band after inverse fast fourier transform
Echo-signalIn each point exist only in a distance unit, and the distance is to inverse fast fourier transform
Wave-number domain base band echo-signal afterwardsBright line in image along orientation is parallel with azimuth axis.
The distance is to the wave-number domain base band echo-signal after inverse fast fourier transformIts expression formula are as follows:IFFT indicates your Fast Fourier Transform (FFT) operation, kyIndicate rectangular coordinate system under distance to
Space wave number, kxIndicate the orientation space wave number under rectangular coordinate system.
4.2 since the distance is to the wave-number domain base band echo-signal after inverse fast fourier transformWith distance
Unrelated error phase φr_indep(ky0,kx) and the rectangular coordinate system (ky,kx) under the wave-number domain base band echo-signal that indicates
W(ky,kx) it is identical as apart from unrelated error phase, therefore using autofocus algorithm to the distance to inverse fast Fourier
Transformed wave-number domain base band echo-signalEstimated with apart from unrelated error phase, obtain distance to inverse fast
The error phase of wave-number domain base band echo-signal after fast Fourier transformation
Step 5, according to error phase φerror(ky,kx) in apart from unrelated error phase φr_indep(ky0,kx) and away from
The error phase of wave-number domain base band echo-signal after the inverse fast fourier transform of descriscentPhase benefit is calculated
Wave-number domain base band echo-signal W after repayingcomp(ky,kx), and then calculate the ISAR imaging of wave-number domain base band echo-signal；Wherein,
φerror(ky,kx) indicate target translational error △ R (ta) caused by error phase.
The specific sub-step of step 5 are as follows:
5.1 according to error phase φerror(ky,kx) in apart from unrelated error phase
φr_indep(ky0,kx), it calculates in target translational error and apart from unrelated translational error Indicate distance to the wave after inverse fast fourier transform
The error phase of number field base band echo-signal.
In 5.2 pairs of target translational errors and apart from unrelated translational errorIt is quasi- to carry out interpolation
It closes, obtains the target translational error after interpolation fitting with distance dependent
5.3 according to the target translational error after interpolation fitting with distance dependentIt is flat that target is calculated
The phase compensation function H of dynamic errorTrCo2(ky,kx), expression formula are as follows:
5.4 utilize the phase compensation function H of target translational errorTrCo2(ky,kx) to the rectangular coordinate system (ky,kx) under
The wave-number domain base band echo-signal W (k of expressiony,kx) phase compensation is carried out, the wave-number domain base band echo letter after obtaining phase compensation
Number Wcomp(ky,kx), expression formula are as follows:
Wcomp(ky,kx)=W (ky,kx)·HTrCo2(ky,kx)
Wherein, dot product is indicated.
5.5 couples of compensated wave-number domain base band echo-signal Wcomp(ky,kx) carry out bidimensional inverse fast fourier transform
(IFFT), the ISAR imaging of wave-number domain base band echo-signal is obtained.
Step 6, Autofocus processing is carried out to the ISAR imaging of wave-number domain base band echo-signal, after obtaining Autofocus processing
ISAR is imaged, and the ISAR imaging after the Autofocus processing can be improved the image quality of ISAR imaging.
Effectiveness of the invention can be described further by following emulation.
Emulation content and interpretation of result:
Emulation experiment: simulation parameter is as shown in table 1:
Table 1
Fig. 2 is the target scattering point relative position schematic diagram of emulation experiment, and wherein aircraft is 35 meters long, 30 meters wide；
It include 4 mark points, respectively mark point 1, mark point 2, mark point 3 and mark point 4 in Fig. 2；
Fig. 3 is flight path figure of the target relative to radar, and target is 11.73 degree relative to the corner of radar.
Method is emulated using conventional translational compensation algorithm, that is, envelope alignment and Autofocus processing scheme and the present invention respectively
Data are handled, and use the processing result of accurate compensation translation as reference, processing result such as Fig. 4 (a), Fig. 4 (b) and Fig. 4 (c)
Shown, Fig. 4 (a) is the distance of error free processing to envelope result schematic diagram, and Fig. 4 (b) is the distance that handles of the present invention to envelope
Result schematic diagram, Fig. 4 (c) are the distances of conventional method processing to envelope result schematic diagram；Translational error is accurately compensated and is used
The imaging results that conventional method is handled and obtained after being handled using the method for the present invention, such as Fig. 5 (a), Fig. 5 (b) and Fig. 5 (c) institute
Show；Fig. 5 (a) is the imaging results schematic diagram for carrying out translational error and accurately compensating, and Fig. 5 (b) is obtained using the method for the present invention
To imaging results schematic diagram, Fig. 5 (c) is the imaging results schematic diagram obtained using conventional method.In order to further to result into
Row explanation amplifies analysis to 4 mark points in Fig. 2, draws the impulse response function of its two-dimentional contour map and orientation
(Impulse Response Function, IRF), as a result as shown in Fig. 6 (a)-Fig. 9 (d)；Wherein, Fig. 6 (a) is to be translatable
The two-dimentional contour map of mark point 1 in Fig. 2 of the accurate compensation deals of error；Fig. 6 (b) be conventional method processing Fig. 2 in mark
The two-dimentional contour map of point 1；Fig. 6 (c) is the two-dimentional contour map of mark point 1 in Fig. 2 of the method for the present invention processing；Fig. 6 (d) is
Accurately the compensating in translational error respectively of mark point 1 in Fig. 2 obtains under conventional method processing and the method for the present invention disposition
The comparative result schematic diagram of orientation sectional view；Fig. 7 (a) is mark point 2 in the Fig. 2 for carry out the accurate compensation deals of translational error
Two-dimentional contour map；
Fig. 7 (b) is the two-dimentional contour map of mark point 2 in Fig. 2 of conventional method processing；Fig. 7 (c) is at the method for the present invention
The two-dimentional contour map of mark point 2 in Fig. 2 of reason；Fig. 7 (d) is that mark point 2 accurately compensates, often in translational error respectively in Fig. 2
The comparative result schematic diagram of the orientation sectional view obtained under the processing of rule method and the method for the present invention disposition；Fig. 8 (a) is flat
The two-dimentional contour map of mark point 3 in Fig. 2 of the dynamic accurate compensation deals of error；Fig. 8 (b) is Fig. 2 acceptance of the bid of conventional method processing
The two-dimentional contour map of note point 3；Fig. 8 (c) is the two-dimentional contour map of mark point 3 in Fig. 2 of the method for the present invention processing；Fig. 8 (d)
It is that mark point 3 is obtained in the case where translational error accurately compensates, conventional method is handled and the method for the present invention disposition respectively in Fig. 2
The comparative result schematic diagram of orientation sectional view；Fig. 9 (a) is the two dimension of mark point 4 in Fig. 2 of the accurate compensation deals of translational error
Contour map；Fig. 9 (b) is the two-dimentional contour map of mark point 4 in Fig. 2 of conventional method processing；Fig. 9 (c) is the method for the present invention
The two-dimentional contour map of mark point 4 in Fig. 2 of processing；Fig. 9 (d) be in Fig. 2 mark point 4 accurately compensate in translational error respectively,
The comparative result schematic diagram of the orientation sectional view obtained under conventional method processing and the method for the present invention disposition；And it calculates
The response pulse duration (Impulse Response Width, IRW) of its orientation, calculated result is as shown in table 2.
Table 2
From Fig. 6 (a)-Fig. 9 (d) as can be seen that the processing that result and translational error that the method for the present invention is handled accurately compensate
As a result more close, illustrate the validity of the method for the present invention；And the two-dimentional contour map of conventional method processing result is more mixed
Disorderly, main lobe and secondary lobe are difficult to separate.It can be seen that the orientation point of the method for the present invention processing result by the IRW calculated result of table 2
Resolution is close with the azimuth resolution of accurate compensation result that is translatable and the azimuth resolution of conventional method processing result is deteriorated,
Resolution loss is greater than 25%.Illustrate effectiveness of the invention.
In conclusion emulation experiment demonstrates correctness of the invention, validity and reliability.
Obviously, various changes and modifications can be made to the invention without departing from essence of the invention by those skilled in the art
Mind and range；In this way, if these modifications and changes of the present invention belongs to the range of the claims in the present invention and its equivalent technologies
Within, then the present invention is also intended to include these modifications and variations.
Claims (9)
1. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA, which is characterized in that including following step
It is rapid:
Step 1, ground ISAR radar emission chirp signal, and Frequency mixing processing is carried out to the target echo signal received,
Base band echo-signal s (t after being mixedr, ta)；Wherein, trIt indicates apart from fast time, taIndicate the orientation time；
Step 2, to the base band echo-signal s (t after mixingr, ta) carry out obtaining that treated apart from pulse pressure apart from pulse pressure processing
Base band echo-signalThen pulse pressure of adjusting the distance treated base band echo-signalTranslational compensation processing is carried out, is obtained
To translational compensation treated base band echo-signal S (fr, ta) and target translational error Δ R (ta)；Wherein, frIndicate distance frequency
Rate；
Step 3, by translational compensation treated base band echo-signal S (fr, ta) wave-number domain is transformed to, it obtains wave-number domain base band and returns
Wave signal W (kr, θ), then by polar format algorithm PFA to wave-number domain base band echo-signal W (kr, θ) and carry out interpolation change
It changes, obtains the wave-number domain base band echo-signal W (k indicated under rectangular coordinate systemy, kx), and calculate target translational error Δ R (ta)
Caused error phase φerror(ky, kx), and then error phase φ is calculatederror(ky, kx) in apart from unrelated error
Phaser_indep(ky0, kx)；
Wherein, krIndicate radial space wave number, θ indicates corner of the target relative to radar, kyIndicate the distance under rectangular coordinate system
To space wave number, kxIndicate the orientation space wave number under rectangular coordinate system；
Step 4, according to error phase φerror(ky, kx) in apart from unrelated error phase φr_indep(ky0, kx), it calculates
The error phase of wave-number domain base band echo-signal after to from distance to inverse fast fourier transformky0Indicate away from
Descriscent wave number center；
Step 5, according to error phase φerror(ky, kx) in apart from unrelated error phase φr_indep(ky0, kx) and distance to
The error phase of wave-number domain base band echo-signal after inverse fast fourier transformPhase compensation is calculated
Wave-number domain base band echo-signal W afterwardscomp(ky, kx), and then calculate the ISAR imaging of wave-number domain base band echo-signal；
Step 6, Autofocus processing is carried out to the ISAR imaging of wave-number domain base band echo-signal, the ISAR after obtaining Autofocus processing
Imaging.
2. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as described in claim 1, feature
It is, in step 1, the base band echo-signal s (t after the mixingr, ta) expression formula are as follows:
Wherein, trIt indicates apart from fast time, taIndicate orientation time, ar(t) the base band echo-signal s (t after mixing is indicatedr, ta)
Distance to window function,Rect indicates rectangular function；TpIndicate the pulse width of chirp signal, γ
Indicate the frequency modulation rate of chirp signal, c indicates that the light velocity, t indicate time variable, and λ indicates the wavelength of chirp signal；R
(ta) indicate that the oblique distance course of the target to radar to the oblique distance course of radar, is configured to multinomial model, table by target
Up to formula are as follows:
R0Indicate the rotation center of target to the initial of radar
Distance, v indicate radial velocity of the target with respect to radar, and a indicates radial acceleration of the target with respect to radar, Rn(ta) indicate n rank with
On high-order translation component, n > 2；(x, y) indicates the initial position relative to target rotation center of target scattering point, and θ is indicated
Corner of the target relative to radar, exp indicate exponential function.
3. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as described in claim 1, feature
It is, it is in step 2, described apart from pulse pressure treated base band echo-signalThe translational compensation treated base band
Echo-signal S (fr, ta) and the target translational error Δ R (ta), expression formula is respectively as follows:
Wherein, ApIt indicates apart from pulse pressure treated base band echo-signalAmplitude, B indicate apart from pulse pressure, treated
Base band echo-signalBandwidth, sinc () indicate sinc function, trIt indicates apart from fast time, R (ta) indicate that target arrives
The oblique distance course of radar, c indicate that the light velocity, λ indicate that the wavelength of chirp signal, exp indicate exponential function, Δ R (ta) indicate
Target translational error, Rn(ta) indicate n rank more than high-order translation component, n > 2；Rect indicates rectangular function, frIndicate distance
Frequency, fcIndicate carrier frequency, taIndicate the orientation time, v indicates radial velocity of the target with respect to radar, and a indicates target with respect to radar
Radial acceleration,Indicate the speed for the target translation that estimation obtains,Indicate the translatory acceleration for the target that estimation obtains, (x,
Y) initial position relative to target rotation center of target scattering point is indicated.
4. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as claimed in claim 3, feature
It is, it is described to obtain translational compensation treated base band echo-signal S (fr, ta), process are as follows:
Pulse pressure of adjusting the distance treated base band echo-signalEnvelope curve carry out fitting of a polynomial, estimation target translation
SpeedWith the translatory acceleration of targetReuse the speed of the target translationWith the translatory acceleration of targetTo away from
From pulse pressure treated base band echo-signalTranslational compensation processing is carried out, translational compensation is obtained treated base band echo
Signal S (fr, ta)。
5. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as claimed in claim 4, feature
It is, in step 3, the wave-number domain base band echo-signal W (kr, θ), the wave-number domain base band that indicates under the rectangular coordinate system
Echo-signal W (ky, kx), the target translational error Δ R (ta) caused by error phase φerror(ky, kx) and the error phase
Position φerror(ky, kx) in apart from unrelated error phase φr_indep(ky0, kx), expression formula is respectively as follows:
W(kr, θ) and=P (kr)exp(-jkr(x sinθ+y cosθ))exp(-jkrΔR(θ))
Wherein, krIndicate radial space wave number,P(kr) indicate wave-number domain base band echo-signal W (kr, θ)
Distance to window function,ΔkrBIndicate radial wave SerComm degree, Δ krB=max (kr)-min(kr)；krc
Indicate radial space wave number center,fcIndicate carrier frequency；Max table seeks maxima operation, and minimum is sought in min expression
Value Operations, W () indicate wave-number domain base band echo-signal,krcIt indicates in radial space wave number
The heart,fcIndicate carrier frequency；kx=krSin θ, ky=krCos θ, Δ krBIndicate radial wave SerComm degree, soφerror(ky, kx) indicate target translational error Δ R (ta) caused by error phase,Δ R (θ) indicates target translational error Δ R (ta) using rotational angle theta as independent variable when
Representation, θ indicate corner of the target relative to radar, φr_indep(ky0, kx) indicate error phase φerror(ky, kx) in
Apart from unrelated error phase, φerror(ky, kx) indicate target translational error Δ R (ta) caused by error phase, Δ R '
(arctan(kx/ky0)) indicate Δ R (arctan (kx/ky)) relative to arctan (kx/ky) first derivative, Δ R " (arctan
(kx/ky0)) indicate Δ R (arctan (kx/ky)) relative to arctan (kx/ky) in ky=ky0When second dervative, Δ R
(arctan(kx/ky)) indicate target translational error Δ R (ta) with cornerRepresentation when for independent variable, ky0
Indicate distance to wave number center, kyIndicate intermediate value of the distance under rectangular coordinate system to space wave number；kxIt indicates under rectangular coordinate system
Orientation space wave number.
6. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as described in claim 1, feature
It is, the sub-step of step 4 are as follows:
The wave-number domain base band echo-signal W (k indicated under the 4.1 interception rectangular coordinate systemsy, kx) a part of wave-number domain in centre
Base band echo-signalDistance is obtained to the wave-number domain base band echo-signal after inverse fast fourier transform
4.2 using autofocus algorithms to the distance to the wave-number domain base band echo-signal after inverse fast fourier transform
Estimated with apart from unrelated error phase, obtain distance to after inverse fast fourier transform wave-number domain base band echo letter
Number error phase
Wherein, the wave-number domain base band echo-signal W (k indicated under the interception rectangular coordinate systemy, kx) intermediate a part
Wave-number domain base band echo-signalIts requirement is: so that the distance is to the wave-number domain after inverse fast fourier transform
Base band echo-signalIn each point exist only in a distance unit, and the distance is to inverse fast Fourier
Transformed wave-number domain base band echo-signalBright line in image along orientation is parallel with azimuth axis.
7. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as described in claim 1, feature
It is, in step 4, the distance is to the wave-number domain base band echo-signal after inverse fast fourier transformIt is expressed
Formula are as follows:IFFT indicates inverse fast fourier transform operation, kyIt indicates under rectangular coordinate system
Distance is to space wave number, kxIndicate the orientation space wave number under rectangular coordinate system.
8. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as described in claim 1, feature
It is, the sub-step of step 5 are as follows:
5.1 according to error phase φerror(ky, kx) in apart from unrelated error phase φr_indep(ky0, kx), it is flat to calculate target
In dynamic error and apart from unrelated translational error
In 5.2 pairs of target translational errors and apart from unrelated translational errorInterpolation fitting is carried out, is obtained
After to interpolation fitting with the target translational error of distance dependent
5.3 according to the target translational error after interpolation fitting with distance dependentTarget translation is calculated
The phase compensation function H of errorTrco2(ky, kx)；
5.4 utilize the phase compensation function H of target translational errorTrCo2(ky, kx) to the rectangular coordinate system (ky, kx) under indicate
Wave-number domain base band echo-signal W (ky, kx) carry out phase compensation, the wave-number domain base band echo-signal after obtaining phase compensation
Wcomp(ky, kx)；
5.5 couples of compensated wave-number domain base band echo-signal Wcomp(ky, kx) bidimensional inverse fast fourier transform is carried out, it obtains
ISAR to wave-number domain base band echo-signal is imaged.
9. a kind of translational compensation and imaging method of the big corner ISAR radar based on PFA as claimed in claim 8, feature
It is, the translational error of the non-space-variant of distance in the target translational errorThe target translational error
Phase compensation function HTrCo2(ky, kx) and the phase compensation after wave-number domain base band echo-signal Wcomp(ky, kx), expression
Formula is respectively as follows:
Wcomp(ky, kx)=W (ky, kx)·HTrCo2(ky, kx)
Wherein,Indicate error phase of the distance to the wave-number domain base band echo-signal after inverse fast fourier transform
Position indicates dot product.
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| CN112305539B (en) * | 2020-09-25 | 2023-11-21 | 北方工业大学 | ArcSAR polar coordinate format imaging method based on spherical wave decomposition |
| CN112255626B (en) * | 2020-10-10 | 2023-09-19 | 中国人民解放军63921部队 | ISAR back projection method based on parameterized translational compensation |
| CN113687355A (en) * | 2021-09-15 | 2021-11-23 | 张远 | Automobile millimeter wave radar circumference imaging method and device |
| CN113687354A (en) * | 2021-09-15 | 2021-11-23 | 张远 | Automobile angle radar imaging method and device |
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