CN106772372B - A kind of real time imagery method and system of Ka wave band carried SAR system - Google Patents
A kind of real time imagery method and system of Ka wave band carried SAR system Download PDFInfo
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- CN106772372B CN106772372B CN201611068315.5A CN201611068315A CN106772372B CN 106772372 B CN106772372 B CN 106772372B CN 201611068315 A CN201611068315 A CN 201611068315A CN 106772372 B CN106772372 B CN 106772372B
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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
- G01S13/9004—SAR image acquisition techniques
- G01S13/9019—Auto-focussing of the SAR signals
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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
Abstract
The invention belongs to Radar Technology fields, are related to a kind of real time imagery method and system of Ka wave band carried SAR system.Described method includes following steps: S1, pre-processes to the raw imaging data of carried SAR system；S2 carries out doppler centroid compensation；S3 carries out Azimuth Pre-filter, extraction, kinematic error compensation and range migration correction processing；S4, calculates doppler frequency rate according to S3 treated raw imaging data, carries out phase compensation according to the doppler frequency rate；S5 carries out orientation process of pulse-compression and lateral displacement compensation deals, obtains output data；S6 obtains haplopia reality image according to the output data, is quantified to haplopia reality image, multiple look processing and splicing obtain real time imagery data.The present invention realizes the Real Time Imaging Technology of Ka wave band carried SAR system, meets ka wave band carried SAR system high-resolution imaging demand, real time imagery effect is good, and focusing effect is good.
Description
Technical field
The invention belongs to Radar Technology field more particularly to a kind of real time imagery method of Ka wave band carried SAR system and
System.
Background technique
High-resolution carried SAR system requirements carrier aircraft unaccelerated flight, but due to by air-flow and carrier aircraft itself etc. because
Element influences, and flight path often deviates from setting track, therefore can introduce kinematic error.The size of kinematic error is to carried SAR
The influential effect of real time imagery is different, gently then causes the signal-to-noise ratio of image decline, resolution ratio reduction, it is heavy then cause image defocus without
Method uses.Different frequency range SAR system is also different to the sensitivity of kinematic error, and the higher radar of frequency range is quicker to kinematic error
Sense, therefore ka wave band carried SAR system wants high relative to common X-band carried SAR system to the sensitivity of kinematic error
Very much.
The real time imagery of carried SAR system is usually by airborne ins data and based on the Doppler's parameter estimate of echo data
The method combined.Since the inertial navigation system precision that previous China's carried SAR system uses is not high, so being generally only accustomed to the use of derivative
According to coarse compensation is carried out, the Doppler's parameter estimate based on echo data is recycled to carry out smart compensation, then to reach high-resolution
The requirement of imaging.Although the introduction of external some High Accuracy Inertial equipment in recent years and the raising of domestic inertial navigation precision,
The characteristics of due to ka wave band carried SAR system, the real time imagery of Ka wave band carried SAR system are also not implemented.
Summary of the invention
The technical problem to be solved by the present invention is in view of the deficiencies of the prior art, provide a kind of Ka wave band carried SAR system
The real time imagery method and system of system.
The technical scheme to solve the above technical problems is that a kind of real time imagery of Ka wave band carried SAR system
Method includes the following steps:
S1 pre-processes the raw imaging data of carried SAR system；
S2 calculates doppler centroid according to the inertial guidance data that carried SAR system obtains, according to doppler centroid
Doppler centroid compensation is carried out to pretreated raw imaging data；
S3 successively carries out Azimuth Pre-filter, extraction, movement to through the compensated raw imaging data of doppler centroid
Error compensation and range migration correction processing；
S4 calculates doppler frequency rate according to S3 treated raw imaging data, according to the doppler frequency rate pair
The raw imaging data handled through range migration correction carries out phase compensation；
S5 carries out orientation process of pulse-compression and lateral displacement compensation deals to the raw imaging data through phase compensation,
Obtain output data；
S6 obtains haplopia reality image according to the output data, carries out quantization to haplopia reality image and multiple look processing obtains
Each single width reality image is spliced to obtain real time imagery data to adjacent single width reality image.
The beneficial effects of the present invention are: being pre-processed to the raw imaging data of carried SAR system, according to inertial guidance data
Doppler centroid is calculated, Doppler center frequency is carried out to pretreated raw imaging data according to doppler centroid
Rate compensation, then successively carry out Azimuth Pre-filter, extraction, kinematic error compensation and range migration correction processing, realize in real time at
Adjacent image center is consistent with phase in the picture time, carries out phase compensation according to doppler frequency rate, finely tunes in real time, orientation
Lateral displacement compensation is carried out after process of pulse-compression, obtains output data, is obtained single width using quantization and multiple look processing and is schemed in fact
Picture, splicing obtain real time imagery data, realize that real time imagery effect is good, and focusing effect is good, and it is high to meet ka wave band carried SAR system
Resolution imaging demand.
Based on the above technical solution, the present invention can also be improved as follows.
Further, the S2 includes: to calculate doppler centroid according to the inertial guidance data that carried SAR systematic survey obtains
fdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft
East orientation speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates carrier aircraft pitch angle, α table
Show carrier aircraft flight-path angle, the λ is carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
Beneficial effect using above-mentioned further scheme is: doppler centroid is calculated according to inertial guidance data, according to more
General Le centre frequency carries out doppler centroid compensation to pretreated raw imaging data, realizes real time imagery effect
Good, focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Further, the S1 include: to the raw imaging data of carried SAR system carry out distance to pulse compression at
Reason, the raw imaging data includes echo signal data.
Further, the kinematic error compensation processing includes: the kinematic error and two calculated according to inertial guidance data
Secondary kinematic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and to extract that treated former
Beginning imaging data carries out kinematic error compensation.
Beneficial effect using above-mentioned further scheme is: a kinematic error being calculated by inertial guidance data and secondary
Kinematic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extract that treated is original
Imaging data carry out kinematic error compensation realize within the real time imagery time adjacent image center it is consistent with phase, in real time at
Picture effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Further, the S5 include: to through phase compensation raw imaging data carry out orientation process of pulse-compression, then into
Row lateral displacement compensation deals obtain output data, and the expression formula of the lateral displacement Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, v indicate carrier aircraft flying speed, R is indicated
The instantaneous oblique distance of radar, θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and v, R and θ are the inertial guidance datas；
The expression formula of the output data Xa is:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/v))
Wherein, the S (f) indicates that echo-signal frequency spectrum, H (f) indicate filter spectrum, and f indicates Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler
Frequency is the variable for converting time-domain signal to frequency domain signal.
Beneficial effect using above-mentioned further scheme is: by carrying out lateral displacement benefit again after orientation process of pulse-compression
It repays, obtains output data, real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging need
It asks.
Further, doppler frequency rate described in the S4 is the variable quantity of the doppler centroid.
Another technical solution that the present invention solves above-mentioned technical problem is as follows: a kind of reality of Ka wave band carried SAR system
When imaging system, comprising:
Preprocessing module is pre-processed for the raw imaging data to carried SAR system；
Doppler centroid compensating module, the inertial guidance data for being obtained according to carried SAR system calculate in Doppler
Frequency of heart carries out doppler centroid compensation to pretreated raw imaging data according to doppler centroid；
First processing module, for pre- to orientation is successively carried out through the compensated raw imaging data of doppler centroid
Filtering, extraction, kinematic error compensation and range migration correction processing；
Phase compensation block calculates doppler frequency rate according to first processing module treated raw imaging data, according to
Phase compensation is carried out to the raw imaging data handled through range migration correction according to the doppler frequency rate；
Orientation pulse compression and bit shift compensation processing module, for carrying out orientation to the raw imaging data through phase compensation
Process of pulse-compression and lateral displacement compensation deals, obtain output data；
Second processing module quantifies haplopia reality image for obtaining haplopia reality image according to the output data
Each single width reality image is obtained with multiple look processing, adjacent single width reality image is spliced to obtain real time imagery data.
The beneficial effects of the present invention are: preprocessing module pre-processes the raw imaging data of carried SAR system, it is more
General Le centre frequency compensating module calculates doppler centroid according to inertial guidance data, is located in advance according to doppler centroid to warp
The raw imaging data of reason carries out doppler centroid compensation, and first processing module successively carries out Azimuth Pre-filter, extraction, fortune
Dynamic error compensation and range migration correction processing realize that adjacent image center is consistent with phase within the real time imagery time,
Phase compensation block carries out phase compensation according to doppler frequency rate, finely tunes in real time, orientation pulse compression and bit shift compensation processing
Module carries out lateral displacement compensation after carrying out orientation process of pulse-compression, obtains output data, Second processing module is quantified
Single width reality image is obtained with multiple look processing, splicing obtains real time imagery data, realizes that real time imagery effect is good, and focusing effect is good,
Meet ka wave band carried SAR system high-resolution imaging demand.
Based on the above technical solution, the present invention can also be improved as follows.
Further, the doppler centroid compensating module includes: used for being obtained according to carried SAR systematic survey
Derivative is according to calculating doppler centroid fdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft
East orientation speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates carrier aircraft pitch angle, α table
Show carrier aircraft flight-path angle, the λ is carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
Beneficial effect using above-mentioned further scheme is: by doppler centroid compensating module according to inertial guidance data
Doppler centroid is calculated, Doppler center frequency is carried out to pretreated raw imaging data according to doppler centroid
Rate compensation realizes that real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Further, the preprocessing module include: to the raw imaging data of carried SAR system carry out distance to pulse
Compression processing, the raw imaging data include echo signal data.
Further, the kinematic error compensation includes: the kinematic error and secondary fortune calculated according to inertial guidance data
Dynamic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and to extract that treated original at
As data carry out kinematic error compensation.
Beneficial effect using above-mentioned further scheme is: a kinematic error being calculated by inertial guidance data and secondary
Kinematic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extract that treated is original
Imaging data carry out kinematic error compensation realize within the real time imagery time adjacent image center it is consistent with phase, in real time at
Picture effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Further, the orientation pulse compression and bit shift compensation processing module include: for through the original of phase compensation
Imaging data carries out orientation process of pulse-compression, then carries out lateral displacement compensation deals, obtains output data, the lateral displacement
The expression formula of Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, v indicate carrier aircraft flying speed, R is indicated
The instantaneous oblique distance of radar, θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and v, R and θ are the inertial guidance datas；
The expression formula of the output data Xa is:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/v))
Wherein, the S (f) indicates that echo-signal frequency spectrum, G (f) indicate filter spectrum, and f indicates Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler
Frequency is the variable for converting time-domain signal to frequency domain signal.
Beneficial effect using above-mentioned further scheme is: by carrying out lateral displacement benefit again after orientation process of pulse-compression
It repays, obtains output data, real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging need
It asks.
Detailed description of the invention
Fig. 1 is the practical course line of carrier aircraft in the prior art and ideal route map；
Fig. 2 is a kind of real time imagery method flow schematic diagram of Ka wave band carried SAR system provided in an embodiment of the present invention；
Fig. 3 is a kind of Real Time Image System structural schematic diagram of Ka wave band carried SAR system provided in an embodiment of the present invention.
Specific embodiment
The principle and features of the present invention will be described below with reference to the accompanying drawings, and the given examples are served only to explain the present invention, and
It is non-to be used to limit the scope of the invention.
Since carrier aircraft is influenced by air-flow and carrier aircraft oneself factor etc., flight path often deviates from setting track, causes to transport
Dynamic error, since kinematic error makes the real time imagery effect of carrier aircraft poor.
As shown in Figure 1, setting track is deviateed in practical flight track, kinematic error Δ R, expression formula are caused are as follows:
ΔrR=Y (tm)sinβ+(H-Z(tm))cosβ
Wherein, β indicates radar antenna side view angle in carrier aircraft, and v indicates carrier aircraft flying speed, and H indicates carrier aircraft relative target field
The height of scape, Rs indicate distance of the carrier aircraft setting track relative to ground imaging band center, and Xn indicates seat of the target in X-axis
Mark, tm indicate time, X (tm)、Y(tm) and Z (tm) indicate coordinate of the radar antenna phase center at the tm moment in carrier aircraft, Δ rR
Indicate error on line of sight, Δ rNIndicate course line error, R0 and R1 are radar antenna phase center reference position and reality in carrier aircraft respectively
Oblique distance of the border position relative to scattering point A.
The embodiment of the present invention solves the problems, such as kinematic error by eliminating error on line of sight, and then realizes real time imagery effect
Improve.
The embodiment of the present invention provides a kind of real time imagery method and system of Ka wave band carried SAR system, as shown in Fig. 2,
The real time imagery method of Ka wave band carried SAR system, includes the following steps:
S1 pre-processes the raw imaging data of carried SAR system；
S2 calculates doppler centroid according to the inertial guidance data that carried SAR system obtains, according to doppler centroid
Doppler centroid compensation is carried out to pretreated raw imaging data；
S3 successively carries out Azimuth Pre-filter, extraction, movement to through the compensated raw imaging data of doppler centroid
Error compensation and range migration correction processing；
S4 calculates doppler frequency rate according to S3 treated raw imaging data, according to the doppler frequency rate pair
The raw imaging data handled through range migration correction carries out phase compensation；
S5 carries out orientation process of pulse-compression and lateral displacement compensation deals to the raw imaging data through phase compensation,
Obtain output data；
S6 obtains haplopia reality image according to the output data, carries out quantization to haplopia reality image and multiple look processing obtains
Each single width reality image is spliced to obtain real time imagery data to adjacent single width reality image.
The raw imaging data of carried SAR system is pre-processed, doppler centroid is calculated according to inertial guidance data,
Doppler centroid compensation, then successively progress side are carried out to pretreated raw imaging data according to doppler centroid
Position pre-filtering, extraction, kinematic error compensation and range migration correction processing, realize the adjacent image center within the real time imagery time
Position is consistent with phase, carries out phase compensation according to doppler frequency rate, finely tunes in real time, carries out after orientation process of pulse-compression horizontal
To bit shift compensation, output data is obtained, obtains single width reality image using quantization and multiple look processing, splicing obtains real time imagery number
According to realization real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Specifically, in the embodiment, the S2 include: the inertial guidance data obtained according to carried SAR systematic survey calculate it is more
General Le centre frequency fdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft
East orientation speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates carrier aircraft pitch angle, α table
Showing carrier aircraft flight-path angle, the λ is carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
Using the doppler centroid f in the prior art based on echo datadcEstimation method, to ground special screne
F is calculated separately using estimation method in the prior art and method provided in an embodiment of the present inventiondc, ground special screne use
Doppler centroid f based on echo datadcThe available accurate f of estimation methoddc, f provided in an embodiment of the present inventiondc
Calculation method and the prior art fdcValue is consistent.
Doppler centroid is calculated according to inertial guidance data, according to doppler centroid to pretreated original image
Data carry out doppler centroid compensation, realize that real time imagery effect is good, focusing effect is good, meets ka wave band carried SAR system
System high-resolution imaging demand.
Specifically, in the embodiment, the S1 include: to the raw imaging data of carried SAR system carry out distance to
Process of pulse-compression, the raw imaging data include echo signal data.The raw imaging data is obtained by airborne radar.
Specifically, in the embodiment, the kinematic error compensation processing includes: the primary fortune calculated according to inertial guidance data
Dynamic error and secondary motion error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction
Treated, and raw imaging data carries out kinematic error compensation.
The kinematic error and secondary motion error calculated by inertial guidance data to through distance to pulse compression, it is more
The compensation of general Le centre frequency, Azimuth Pre-filter and the raw imaging data that extracts that treated carry out kinematic error compensation and realize in reality
When imaging time in adjacent image center it is consistent with phase, real time imagery effect is good, and focusing effect is good, meets ka wave band machine
Carry SAR system high-resolution imaging demand.
Specifically, in the embodiment, the S5 includes: to carry out orientation pulse pressure to the raw imaging data through phase compensation
Contracting processing, then lateral displacement compensation deals are carried out, output data is obtained, the expression formula of the lateral displacement Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, v indicate carrier aircraft flying speed, R is indicated
The instantaneous oblique distance of radar, θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and v, R and θ are the inertial guidance datas；
Orientation displacement is lateral displacement, and orientation signal can be equivalent to linear FM signal, if linear FM signal
A doppler centroid is modulated, pulse compression is carried out to it can generate lateral displacement, and the expression formula of lateral displacement is:
Wherein: fdcIt is doppler centroid, μ is doppler frequency rate, and v is carrier aircraft flying speed.Its Doppler FM
The expression formula of rate is:
Wherein: v is carrier aircraft flying speed, and θ indicates that carrier aircraft pitch angle, R indicate the instantaneous oblique distance of radar, and the λ is carried SAR
System parameter.
The expression formula of doppler frequency rate, which is brought into the expression formula of lateral displacement, to be obtained:
The expression formula of the output data Xa is:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/v))
Wherein, the S (f) indicates that echo-signal frequency spectrum, H (f) indicate filter spectrum, and f indicates Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler
Frequency is the variable for converting time-domain signal to frequency domain signal, and the time-domain signal is echo-signal etc..
In order to eliminate the lateral displacement as caused by doppler centroid, can use in doppler centroid domain,
To signal spectrum S (f) and filter spectrum H (f) product multiplied by a linear phase termThen again
Converting the signal into time-domain signal by inverse Fourier transform ifft () can eliminate.
By carrying out lateral displacement compensation again after orientation process of pulse-compression, output data is obtained, real time imagery effect is good,
Focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Specifically, in the embodiment, doppler frequency rate described in the S4 is the variation of the doppler centroid
Amount.
The embodiment of the present invention provides a kind of Real Time Image System of Ka wave band carried SAR system, as shown in figure 3, Ka wave band
The Real Time Image System of carried SAR system, comprising:
Preprocessing module is pre-processed for the raw imaging data to carried SAR system；
Doppler centroid compensating module, the inertial guidance data for being obtained according to carried SAR system calculate in Doppler
Frequency of heart carries out doppler centroid compensation to pretreated raw imaging data according to doppler centroid；
First processing module, for pre- to orientation is successively carried out through the compensated raw imaging data of doppler centroid
Filtering, extraction, kinematic error compensation and range migration correction processing；
Phase compensation block, for calculating Doppler FM according to first processing module treated raw imaging data
Rate carries out phase compensation to the raw imaging data handled through range migration correction according to the doppler frequency rate；
Orientation pulse compression and bit shift compensation processing module, for carrying out orientation to the raw imaging data through phase compensation
Process of pulse-compression and lateral displacement compensation deals, obtain output data；
Second processing module quantifies haplopia reality image for obtaining haplopia reality image according to the output data
Each single width reality image is obtained with multiple look processing, adjacent single width reality image is spliced to obtain real time imagery data.
Preprocessing module pre-processes the raw imaging data of carried SAR system, and doppler centroid compensates mould
Root tuber according to inertial guidance data calculate doppler centroid, according to doppler centroid to pretreated raw imaging data into
The compensation of row doppler centroid, first processing module successively carry out Azimuth Pre-filter, extraction, kinematic error compensation and distance and move
Dynamic correction process realizes that adjacent image center is consistent with phase within the real time imagery time, and phase compensation block is according to more
General Le frequency modulation rate carries out phase compensation, finely tunes in real time, and orientation pulse compression and bit shift compensation processing module carry out orientation pulse pressure
Lateral displacement compensation is carried out after contracting processing, obtains output data, Second processing module carries out quantization and multiple look processing obtains single width
Real image, splicing obtain real time imagery, realize that real time imagery effect is good, and focusing effect is good, and it is high to meet ka wave band carried SAR system
Resolution imaging demand.
Specifically, in the embodiment, the doppler centroid compensating module includes: for according to carried SAR system
It measures obtained inertial guidance data and calculates doppler centroid fdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft
East orientation speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates carrier aircraft pitch angle, α table
Show carrier aircraft flight-path angle, the λ is carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
Doppler centroid is calculated according to inertial guidance data by doppler centroid compensating module, according in Doppler
Frequency of heart carries out doppler centroid compensation to pretreated raw imaging data, realizes that real time imagery effect is good, focuses
Effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Specifically, in the embodiment, the preprocessing module includes: to carry out to the raw imaging data of carried SAR system
Distance to process of pulse-compression, the raw imaging data includes echo signal data.
Specifically, in the embodiment, the kinematic error compensation includes: to be missed according to the primary movement that inertial guidance data calculates
Difference and secondary motion error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction handle
Raw imaging data afterwards carries out kinematic error compensation.
The kinematic error and secondary motion error calculated by inertial guidance data to through distance to pulse compression, it is more
The compensation of general Le centre frequency, Azimuth Pre-filter and the raw imaging data that extracts that treated carry out kinematic error compensation and realize in reality
When imaging time in adjacent image center it is consistent with phase, real time imagery effect is good, and focusing effect is good, meets ka wave band machine
Carry SAR system high-resolution imaging demand.
Specifically, in the embodiment, the orientation pulse compression and bit shift compensation processing module include: for through phase
The raw imaging data of compensation carries out orientation process of pulse-compression, then carries out lateral displacement compensation deals, obtains output data, institute
The expression formula for stating lateral displacement Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, v indicate carrier aircraft flying speed, R is indicated
The instantaneous oblique distance of radar, θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and v, R and θ are the inertial guidance datas；
The expression formula of the output data Xa is:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/v))
Wherein, the S (f) indicates that echo-signal frequency spectrum, H (f) indicate filter spectrum, and f indicates Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler
Frequency is the variable for converting time-domain signal to frequency domain signal, and the time-domain signal is echo-signal etc..
By carrying out lateral displacement compensation again after orientation process of pulse-compression, output data is obtained, real time imagery effect is good,
Focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demand.
Specifically, in the embodiment, the doppler frequency rate is the variable quantity of the Doppler frequency.
The foregoing is merely presently preferred embodiments of the present invention, is not intended to limit the invention, it is all in spirit of the invention and
Within principle, any modification, equivalent replacement, improvement and so on be should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of real time imagery method of Ka wave band carried SAR system, which comprises the steps of:
S1 pre-processes the raw imaging data of carried SAR system；
S2 calculates doppler centroid according to the inertial guidance data that carried SAR system obtains, according to doppler centroid to warp
Pretreated raw imaging data carries out doppler centroid compensation；
S3 successively carries out Azimuth Pre-filter, extraction, kinematic error to through the compensated raw imaging data of doppler centroid
Compensation and range migration correction processing；
S4 calculates doppler frequency rate according to S3 treated raw imaging data, according to the doppler frequency rate to through away from
Raw imaging data from migration correction process carries out phase compensation；
S5 carries out orientation process of pulse-compression and lateral displacement compensation deals to the raw imaging data through phase compensation, obtains
Output data；
S6 obtains haplopia reality image according to the output data, to haplopia reality image carry out quantization and multiple look processing obtain it is each
Single width reality image is spliced to obtain real time imagery data to adjacent single width reality image.
2. a kind of real time imagery method of Ka wave band carried SAR system according to claim 1, which is characterized in that the S2
It include: that doppler centroid f is calculated according to the inertial guidance data that carried SAR systematic survey obtainsdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft east orientation
Speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates that carrier aircraft pitch angle, α indicate to carry
Machine flight-path angle, the λ are carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
3. a kind of real time imagery method of Ka wave band carried SAR system according to claim 2, which is characterized in that the S1
Include: to the raw imaging data of carried SAR system carry out distance to process of pulse-compression, the raw imaging data includes
Echo signal data.
4. a kind of real time imagery method of Ka wave band carried SAR system according to claim 3, which is characterized in that the fortune
Dynamic error compensation processing include: the kinematic error calculated according to inertial guidance data and secondary motion error to through distance to
It pulse compression, doppler centroid compensation, Azimuth Pre-filter and extracts treated raw imaging data and carries out kinematic error
Compensation.
5. a kind of real time imagery method of Ka wave band carried SAR system according to claim 4, which is characterized in that the S5
Include: orientation process of pulse-compression to be carried out to the raw imaging data through phase compensation, then carry out lateral displacement compensation deals, obtains
Expression formula to output data, the lateral displacement Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, ν indicate carrier aircraft flying speed, R indicates radar
Instantaneous oblique distance, Θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and ν, R and Θ are the inertial guidance datas；
The output data xaExpression formula be:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/ ν))
Wherein, the S (f) indicates that echo-signal frequency spectrum, H (f) indicate that filter spectrum, f indicate Doppler frequency, the S (f)
It is calculated by echo signal data, H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler frequency
It is the variable for converting time-domain signal to frequency domain signal.
6. a kind of real time imagery method of Ka wave band carried SAR system, feature described in -5 any one exist according to claim 1
In doppler frequency rate described in the S4 is the variable quantity of the Doppler frequency.
7. a kind of Real Time Image System of Ka wave band carried SAR system characterized by comprising
Preprocessing module is pre-processed for the raw imaging data to carried SAR system；
Doppler centroid compensating module, the inertial guidance data for being obtained according to carried SAR system calculate Doppler center frequency
Rate carries out doppler centroid compensation to pretreated raw imaging data according to doppler centroid；
First processing module, for successively carrying out orientation pre-flock to through the compensated raw imaging data of doppler centroid
Wave, extraction, kinematic error compensation and range migration correction processing；
Phase compensation block, for calculating doppler frequency rate according to first processing module treated raw imaging data, according to
Phase compensation is carried out to the raw imaging data handled through range migration correction according to the doppler frequency rate；
Orientation pulse compression and bit shift compensation processing module, for carrying out orientation pulse to the raw imaging data through phase compensation
Compression processing and lateral displacement compensation deals, obtain output data；
Second processing module, for obtaining haplopia reality image according to the output data, to haplopia reality image carry out quantization and it is more
Depending on handling to obtain each single width reality image, adjacent single width reality image is spliced to obtain real time imagery data.
8. a kind of Real Time Image System of Ka wave band carried SAR system according to claim 7, which is characterized in that described
Doppler centroid compensating module includes: that the inertial guidance data for being obtained according to carried SAR systematic survey calculates in Doppler
Frequency of heart fdc, fdcExpression formula be:
Wherein, λ indicates radar operation wavelength, and R indicates the instantaneous oblique distance of radar, VNIndicate carrier aircraft north orientation speed, VEIndicate carrier aircraft east orientation
Speed, VDWith indicating carrier aircraft Xiang Sudu, H indicate the height of carrier aircraft relative target scene, and Θ indicates that carrier aircraft pitch angle, α indicate to carry
Machine flight-path angle, the λ are carried SAR system parameter, R, VN、VE、VD, H, Θ and α be the inertial guidance data；
Doppler centroid compensation is carried out to pretreated raw imaging data according to doppler centroid.
9. a kind of Real Time Image System of Ka wave band carried SAR system according to claim 8, which is characterized in that described
Kinematic error compensation include: the kinematic error calculated according to inertial guidance data and secondary motion error to through distance to arteries and veins
It punching press contracting, doppler centroid compensation, Azimuth Pre-filter and extracts treated raw imaging data and carries out kinematic error benefit
It repays.
10. a kind of Real Time Image System of Ka wave band carried SAR system according to claim 9, which is characterized in that described
Orientation pulse compression and bit shift compensation processing module include: for carrying out orientation pulse to the raw imaging data through phase compensation
Compression processing, then lateral displacement compensation deals are carried out, output data is obtained, the expression formula of the lateral displacement Δ x is:
Wherein, Δ x indicates lateral displacement, fdcIndicate that the doppler centroid, ν indicate carrier aircraft flying speed, R indicates radar
Instantaneous oblique distance, Θ indicate carrier aircraft pitch angle, and the λ is carried SAR system parameter, and ν, R and Θ are the inertial guidance datas；
The output data xaExpression formula be:
xa=ifft (S (f) × H (f) × exp (j2 π f × Δ x/ ν))
Wherein, the S (f) indicates that echo-signal frequency spectrum, H (f) indicate that filter spectrum, f indicate Doppler frequency, the S (f)
It is calculated by echo signal data, H (f) is calculated by carried SAR system parameter and inertial guidance data, the Doppler frequency
It is the variable for converting time-domain signal to frequency domain signal.
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