CN106772372A - A kind of real time imagery method and system of Ka wave bands carried SAR system - Google Patents
A kind of real time imagery method and system of Ka wave bands carried SAR system Download PDFInfo
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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
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Abstract
The invention belongs to Radar Technology field, it is related to a kind of real time imagery method and system of Ka wave bands carried SAR system.Methods described comprises the following steps：S1, the raw imaging data to carried SAR system is pre-processed；S2, carries out doppler centroid compensation；S3, carries out the treatment of Azimuth Pre-filter, extraction, kinematic error compensation and range migration correction；S4, doppler frequency rate is calculated according to the raw imaging data after S3 treatment, and phase compensation is carried out according to the doppler frequency rate；S5, carries out orientation process of pulse-compression, and lateral displacement compensation deals, obtains output data；S6, according to the output data obtain haplopia reality image, to haplopia reality image quantified, 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 systems, meets ka wave band carried SAR system high-resolution imaging demands, and 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 bands carried SAR system and
System.
Background technology
High-resolution carried SAR system requirements carrier aircraft unaccelerated flight, but due to by air-flow and carrier aircraft itself etc. because
Element influence, its flight path often deviates from setting flight path, therefore can introduce kinematic error.The size of kinematic error is to carried SAR
The influential effect of real time imagery is different, and the signal to noise ratio for gently then causing image declines, resolution ratio is reduced, it is heavy then cause image defocus without
Method is used.Different frequency range SAR system is also different to the sensitivity of kinematic error, and frequency range radar higher is quicker to kinematic error
Sense, therefore ka wave band carried SAR systems will height relative to common X-band carried SAR system to the sensitivity of kinematic error
A lot.
The real time imagery of carried SAR system is generally by airborne inses data and Doppler's parameter estimate based on echo data
The method being combined.Because the inertial navigation system precision that conventional China's carried SAR system is used is not high, so being typically only accustomed to the use of derivative
According to coarse compensation is carried out, the Doppler's parameter estimate based on echo data is then recycled to carry out smart compensation, to reach high-resolution
The requirement of imaging.Although the introduction and the raising of domestic inertial navigation precision of some High Accuracy Inertial equipment of foreign countries in recent years,
The characteristics of due to ka wave band carried SAR systems, the real time imagery of Ka wave band carried SAR systems is also not implemented.
The content of the invention
The technical problems to be solved by the invention are directed to the deficiencies in the prior art, there is provided a kind of Ka wave bands carried SAR system
The real time imagery method and system of system.
The technical scheme that the present invention solves above-mentioned technical problem is as follows：A kind of real time imagery of Ka wave bands carried SAR system
Method, comprises the following steps：
S1, the raw imaging data to carried SAR system is pre-processed；
S2, calculates doppler centroid, according to doppler centroid according to the inertial guidance data that carried SAR system is obtained
Doppler centroid compensation is carried out to pretreated raw imaging data；
S3, to being compensated through doppler centroid after raw imaging data carry out successively Azimuth Pre-filter, extraction, motion
Error compensation and range migration correction are processed；
S4, calculates doppler frequency rate, according to the doppler frequency rate pair according to the raw imaging data after S3 treatment
The raw imaging data processed through range migration correction carries out phase compensation；
S5, orientation process of pulse-compression, and lateral displacement compensation deals are carried out to the raw imaging data through phase compensation,
Obtain output data；
S6, haplopia reality image is obtained according to the output data, haplopia reality image is quantified and multiple look processing is obtained
Each single width reality image, splice and obtains real time imagery data to adjacent single width reality image.
The beneficial effects of the invention are as follows：Raw imaging data to carried SAR system is pre-processed, according to inertial guidance data
Doppler centroid is calculated, Doppler center is carried out frequently to pretreated raw imaging data according to doppler centroid
Rate compensate, then carry out successively Azimuth Pre-filter, extractions, kinematic error compensation and range migration correction treatment, realization in real time into
As adjacent image center is consistent with phase in the time, phase compensation is carried out according to doppler frequency rate, in real time fine setting, orientation
Lateral displacement compensation is carried out after process of pulse-compression, output data is obtained, then by quantifying to obtain single width figure in fact with multiple look processing
Picture, splicing obtains real time imagery data, realizes that real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR systems high
Resolution imaging demand.
On the basis of above-mentioned technical proposal, the present invention can also do following improvement.
Further, the S2 includes：Doppler centroid is calculated according to the inertial guidance data that carried SAR systematic survey is obtained
fdc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft
East orientation speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, α tables
Show carrier aircraft flight-path angle, the λ is carried SAR systematic 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 many
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 demands.
Further, the S1 includes：The raw imaging data of carried SAR system is entered row distance to pulse compression at
Reason, the raw imaging data includes echo signal data.
Further, the kinematic error compensation treatment includes：According to the kinematic error and two that inertial guidance data is calculated
Secondary kinematic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction process after original
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 extraction process after it 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 into
As effect is good, focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Further, the S5 includes：Orientation process of pulse-compression is carried out to the raw imaging data through phase compensation, then is entered
Row lateral displacement compensation deals, obtain output data, and the expression formula of the lateral displacement Δ x is：
Wherein, Δ x represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R is represented
The instantaneous oblique distance of radar, θ represents the carrier aircraft angle of pitch, and the λ is carried SAR systematic 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) represents echo-signal frequency spectrum, and H (f) represents filter spectrum, and f represents Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler
Frequency is the variable that time-domain signal is converted into frequency domain signal.
Beneficial effect using above-mentioned further scheme is：By the way that lateral displacement benefit is carried out after orientation process of pulse-compression again
Repay, obtain output data, real time imagery effect is good, and focusing effect is good, meet ka wave band carried SAR system high-resolution imaging need
Ask.
Further, doppler frequency rate described in the S4 is the variable quantity of the doppler centroid.
Another technical scheme that the present invention solves above-mentioned technical problem is as follows：A kind of reality of Ka wave bands carried SAR system
When imaging system, including：
Pretreatment module, pre-processes 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 is calculated in Doppler
Frequency of heart, doppler centroid compensation is carried out according to doppler centroid to pretreated raw imaging data；
First processing module, carries out orientation pre- successively for the raw imaging data after to being compensated through doppler centroid
Filtering, extraction, kinematic error compensation and range migration correction treatment；
Phase compensation block, doppler frequency rate is calculated according to the raw imaging data after first processing module treatment, according to
Phase compensation is carried out to the raw imaging data processed 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, for obtaining haplopia reality image according to the output data, quantifies to haplopia reality image
Each single width reality image is obtained with multiple look processing, adjacent single width reality image splice and obtains real time imagery data.
The beneficial effects of the invention are as follows：Pretreatment module is pre-processed to the raw imaging data of carried SAR system, many
General Le centre frequency compensating module calculates doppler centroid according to inertial guidance data, according to doppler centroid to through pre- place
The raw imaging data of reason carries out doppler centroid compensation, and first processing module carries out Azimuth Pre-filter, extraction, fortune successively
Dynamic error compensation and range migration correction treatment, 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, in real time fine setting, and orientation pulse compression and bit shift compensation are processed
Module carries out lateral displacement compensation after carrying out orientation process of pulse-compression, obtains output data, and 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 demands.
On the basis of above-mentioned technical proposal, the present invention can also do following improvement.
Further, the doppler centroid compensating module includes：It is used for what is obtained according to carried SAR systematic survey
Derivative is according to calculating doppler centroid fdc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft
East orientation speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, α tables
Show carrier aircraft flight-path angle, the λ is carried SAR systematic 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 is carried out frequently to pretreated raw imaging data according to doppler centroid
Rate is compensated, and realizes that real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Further, the pretreatment module includes：The raw imaging data of carried SAR system is entered row distance to pulse
Compression is processed, and the raw imaging data includes echo signal data.
Further, the kinematic error compensation includes：According to a kinematic error and secondary fortune that inertial guidance data is calculated
Dynamic error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction process after it is original into
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 extraction process after it 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 into
As effect is good, focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Further, the orientation pulse compression and bit shift compensation processing module include：For to 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 represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R is represented
The instantaneous oblique distance of radar, θ represents the carrier aircraft angle of pitch, and the λ is carried SAR systematic 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) represents echo-signal frequency spectrum, and G (f) represents filter spectrum, and f represents Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler
Frequency is the variable that time-domain signal is converted into frequency domain signal.
Beneficial effect using above-mentioned further scheme is：By the way that lateral displacement benefit is carried out after orientation process of pulse-compression again
Repay, obtain output data, real time imagery effect is good, and focusing effect is good, meet ka wave band carried SAR system high-resolution imaging need
Ask.
Brief description of the drawings
Fig. 1 is the actual course line of carrier aircraft in the prior art and preferable route map；
Fig. 2 is a kind of real time imagery method flow schematic diagram of Ka wave bands carried SAR system provided in an embodiment of the present invention；
Fig. 3 is a kind of Real Time Image System structural representation of Ka wave bands carried SAR system provided in an embodiment of the present invention.
Specific embodiment
Principle of the invention and feature are described below in conjunction with accompanying drawing, example is served only for explaining the present invention, and
It is non-for limiting the scope of the present invention.
Because carrier aircraft is influenceed by air-flow and carrier aircraft oneself factor etc., its flight path often deviates from setting track, causes fortune
Dynamic error, due to kinematic error so that the real time imagery effect of carrier aircraft is poor.
As shown in figure 1, setting track is deviateed in practical flight track, kinematic error Δ R is caused, its expression formula is：
ΔrR=Y (tm)sinβ+(H-Z(tm))cosβ
Wherein, β represents radar antenna side-looking angle in carrier aircraft, and v represents carrier aircraft flying speed, and H represents carrier aircraft relative target
The height of scape, Rs represents distance of the carrier aircraft setting track relative to ground imaging band center, and Xn represents seat of the target in X-axis
Mark, tm represents time, X (tm)、Y(tm) and Z (tm) represent coordinate of the radar antenna phase center at the tm moment, Δ r in carrier aircraftR
Represent error on line of sight, Δ rNCourse line error is represented, R0 and R1 is respectively radar antenna phase center reference position and reality in carrier aircraft
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 bands carried SAR system, as shown in Fig. 2
The real time imagery method of Ka wave band carried SAR systems, comprises the following steps：
S1, the raw imaging data to carried SAR system is pre-processed；
S2, calculates doppler centroid, according to doppler centroid according to the inertial guidance data that carried SAR system is obtained
Doppler centroid compensation is carried out to pretreated raw imaging data；
S3, to being compensated through doppler centroid after raw imaging data carry out successively Azimuth Pre-filter, extraction, motion
Error compensation and range migration correction are processed；
S4, calculates doppler frequency rate, according to the doppler frequency rate pair according to the raw imaging data after S3 treatment
The raw imaging data processed through range migration correction carries out phase compensation；
S5, orientation process of pulse-compression, and lateral displacement compensation deals are carried out to the raw imaging data through phase compensation,
Obtain output data；
S6, haplopia reality image is obtained according to the output data, haplopia reality image is quantified and multiple look processing is obtained
Each single width reality image, splice and obtains real time imagery data to adjacent single width reality image.
Raw imaging data to carried SAR system is pre-processed, and doppler centroid is calculated according to inertial guidance data,
Doppler centroid compensation, then the side of carrying out successively are carried out to pretreated raw imaging data according to doppler centroid
The treatment of position pre-filtering, extraction, kinematic error compensation and range migration correction, realizes the adjacent image center within the real time imagery time
Position is consistent with phase, and phase compensation is carried out according to doppler frequency rate, and fine setting, carries out horizontal stroke in real time after orientation process of pulse-compression
To bit shift compensation, output data is obtained, then by quantifying to obtain single width reality image with multiple look processing, splicing obtains real time imagery number
According to, realize that real time imagery effect is good, focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Specifically, in the embodiment, the S2 includes：The inertial guidance data obtained according to carried SAR systematic survey calculates many
General Le centre frequency fdc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft
East orientation speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, α tables
Show carrier aircraft flight-path angle, the λ is carried SAR systematic 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 based on echo data of the prior artdcMethod of estimation, to ground special screne
F is calculated using method of estimation of the prior art and method provided in an embodiment of the present invention respectivelydc, ground special screne use
Doppler centroid f based on echo datadcMethod of estimation can obtain accurate fdc, f provided in an embodiment of the present inventiondc
Computational methods and 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, and focusing effect is good, meet ka wave band carried SARs system
System high-resolution imaging demand.
Specifically, in the embodiment, the S1 includes：The raw imaging data of carried SAR system is entered row distance to
Process of pulse-compression, the raw imaging data includes echo signal data.The raw imaging data is obtained by airborne radar.
Specifically, in the embodiment, the kinematic error compensation treatment includes：According to the once fortune that inertial guidance data is calculated
Dynamic error and secondary motion error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction
Raw imaging data after treatment carries out kinematic error compensation.
A kinematic error being calculated by inertial guidance data and secondary motion error to through distance to pulse compression, many
The general raw imaging data strangled after centre frequency compensation, Azimuth Pre-filter and extraction treatment carries out kinematic error compensation and realizes 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 machines
Carry SAR system high-resolution imaging demand.
Specifically, in the embodiment, the S5 includes：Pulse pressure in orientation is carried out to the raw imaging data through phase compensation
Contracting is processed, then carries out lateral displacement compensation deals, obtains output data, and the expression formula of the lateral displacement Δ x is：
Wherein, Δ x represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R is represented
The instantaneous oblique distance of radar, θ represents the carrier aircraft angle of pitch, and the λ is carried SAR systematic 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
One doppler centroid of modulation, pulse compression is carried out to it can produce the expression formula of lateral displacement, lateral displacement to be：
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 represents the carrier aircraft angle of pitch, and R represents the instantaneous oblique distance of radar, and the λ is carried SAR
Systematic parameter.
Can be obtained in the expression formula that the expression formula of doppler frequency rate is brought into lateral displacement：
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) represents echo-signal frequency spectrum, and H (f) represents filter spectrum, and f represents Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler
Frequency is the variable that time-domain signal is converted into frequency domain signal, and the time-domain signal is echo-signal etc..
In order to eliminate due to the lateral displacement that doppler centroid is caused, can use in doppler centroid domain,
To signal spectrum S (f) and filter spectrum H (f) product multiplied by with a linear phase termThen again
Eliminated by converting the signal into time-domain signal by inverse Fourier transform ifft ().
By carrying out lateral displacement compensation after orientation process of pulse-compression again, output data is obtained, real time imagery effect is good,
Focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Specifically, in the embodiment, doppler frequency rate described in the S4 is the change of the doppler centroid
Amount.
The embodiment of the present invention provides a kind of Real Time Image System of Ka wave bands carried SAR system, as shown in figure 3, Ka wave bands
The Real Time Image System of carried SAR system, including：
Pretreatment module, pre-processes 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 is calculated in Doppler
Frequency of heart, doppler centroid compensation is carried out according to doppler centroid to pretreated raw imaging data；
First processing module, carries out orientation pre- successively for the raw imaging data after to being compensated through doppler centroid
Filtering, extraction, kinematic error compensation and range migration correction treatment；
Phase compensation block, for being processed according to first processing module after raw imaging data calculate Doppler FM
Rate, phase compensation is carried out according to the doppler frequency rate to the raw imaging data processed through range migration correction；
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, for obtaining haplopia reality image according to the output data, quantifies to haplopia reality image
Each single width reality image is obtained with multiple look processing, adjacent single width reality image splice and obtains real time imagery data.
Pretreatment module is pre-processed to the raw imaging data of carried SAR system, doppler centroid compensation mould
Root tuber calculates doppler centroid according to inertial guidance data, and pretreated raw imaging data is entered according to doppler centroid
Row doppler centroid is compensated, and first processing module carries out Azimuth Pre-filter, extraction, kinematic error compensation and distance and moves successively
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, fine setting 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 treatment, output data is obtained, Second processing module quantify and multiple look processing obtains single width
Real image, splicing obtains real time imagery, realizes that real time imagery effect is good, and focusing effect is good, meets ka wave band carried SAR systems high
Resolution imaging demand.
Specifically, in the embodiment, the doppler centroid compensating module includes：For according to carried SAR system
The inertial guidance data that measurement is obtained calculates doppler centroid fdc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft
East orientation speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, α tables
Show carrier aircraft flight-path angle, the λ is carried SAR systematic 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 on
Effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Specifically, in the embodiment, the pretreatment module includes：Raw imaging data to carried SAR system is carried out
Distance to process of pulse-compression, the raw imaging data include echo signal data.
Specifically, in the embodiment, the kinematic error compensation includes：The once motion calculated according to inertial guidance data is missed
Difference and secondary motion error to through distance to pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction process
Raw imaging data afterwards carries out kinematic error compensation.
A kinematic error being calculated by inertial guidance data and secondary motion error to through distance to pulse compression, many
The general raw imaging data strangled after centre frequency compensation, Azimuth Pre-filter and extraction treatment carries out kinematic error compensation and realizes 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 machines
Carry SAR system high-resolution imaging demand.
Specifically, in the embodiment, the orientation pulse compression and bit shift compensation processing module include：For to 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
Stating the expression formula of lateral displacement Δ x is：
Wherein, Δ x represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R is represented
The instantaneous oblique distance of radar, θ represents the carrier aircraft angle of pitch, and the λ is carried SAR systematic 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) represents echo-signal frequency spectrum, and H (f) represents filter spectrum, and f represents Doppler frequency, described
S (f) is calculated by echo signal data, and H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler
Frequency is the variable that time-domain signal is converted into frequency domain signal, and the time-domain signal is echo-signal etc..
By carrying out lateral displacement compensation after orientation process of pulse-compression again, output data is obtained, real time imagery effect is good,
Focusing effect is good, meets ka wave band carried SAR system high-resolution imaging demands.
Specifically, in the embodiment, the doppler frequency rate is the variable quantity of the Doppler frequency.
The foregoing is only presently preferred embodiments of the present invention, be not intended to limit the invention, it is all it is of the invention spirit and
Within principle, any modification, equivalent substitution and improvements made etc. should be included within the scope of the present invention.
Claims (10)
1. a kind of real time imagery method of Ka wave bands carried SAR system, it is characterised in that comprise the following steps：
S1, the raw imaging data to carried SAR system is pre-processed；
S2, calculates doppler centroid, according to doppler centroid to warp according to the inertial guidance data that carried SAR system is obtained
The raw imaging data of pretreatment carries out doppler centroid compensation；
S3, to being compensated through doppler centroid after raw imaging data carry out Azimuth Pre-filter, extraction, kinematic error successively
Compensation and range migration correction treatment；
S4, according to S3 treatment after raw imaging data calculate doppler frequency rate, according to the doppler frequency rate to through away from
Raw imaging data from migration correction process carries out phase compensation；
S5, orientation process of pulse-compression, and lateral displacement compensation deals are carried out to the raw imaging data through phase compensation, are obtained
Output data；
S6, haplopia reality image is obtained according to the output data, haplopia reality image is quantified and multiple look processing obtains each
Single width reality image, splice and obtains real time imagery data to adjacent single width reality image.
2. a kind of real time imagery method of Ka wave bands carried SAR system according to claim 1, it is characterised in that the S2
Including：Doppler centroid f is calculated according to the inertial guidance data that carried SAR systematic survey is obtaineddc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft east orientation
Speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, and α represents load
Machine flight-path angle, the λ is carried SAR systematic 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 bands carried SAR system according to claim 2, it is characterised in that the S1
Including：The raw imaging data of carried SAR system is entered row 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 bands carried SAR system according to claim 3, it is characterised in that the fortune
Dynamic error compensation treatment includes：A kinematic error being calculated according to inertial guidance data and secondary motion error to through distance to
Raw imaging data after pulse compression, doppler centroid compensation, Azimuth Pre-filter and extraction treatment carries out kinematic error
Compensation.
5. a kind of real time imagery method of Ka wave bands carried SAR system according to claim 4, it is characterised in that the S5
Including：Orientation process of pulse-compression is carried out to the raw imaging data through phase compensation, then carries out lateral displacement compensation deals, obtained
To output data, the expression formula of the lateral displacement Δ x is：
Wherein, Δ x represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R represents radar
Instantaneous oblique distance, θ represents the carrier aircraft angle of pitch, and the λ is carried SAR systematic 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) represents echo-signal frequency spectrum, and H (f) represents filter spectrum, and f represents Doppler frequency, the S (f)
Calculated by echo signal data, H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler frequency
It is the variable that time-domain signal is converted into frequency domain signal.
6. a kind of real time imagery method of Ka wave bands carried SAR system according to claim 1-5 any one, its feature exists
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 bands carried SAR system, it is characterised in that including：
Pretreatment module, pre-processes 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 calculates Doppler center frequently
Rate, doppler centroid compensation is carried out according to doppler centroid to pretreated raw imaging data；
First processing module, orientation pre-flock is carried out for the raw imaging data after to being compensated through doppler centroid successively
The treatment of ripple, extraction, kinematic error compensation and range migration correction；
Phase compensation block, for being processed according to first processing module after raw imaging data calculate doppler frequency rate, according to
Phase compensation is carried out to the raw imaging data processed 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 is processed, and lateral displacement compensation deals, obtains output data；
Second processing module, for obtaining haplopia reality image according to the output data, to haplopia reality image quantify and many
Each single width reality image is obtained depending on treatment, adjacent single width reality image splice and obtains real time imagery data.
8. the Real Time Image System of a kind of Ka wave bands carried SAR system according to claim 7, it is characterised in that described
Doppler centroid compensating module includes：Inertial guidance data for being obtained according to carried SAR systematic survey is calculated in Doppler
Frequency of heart fdc, fdcExpression formula be：
Wherein, λ represents radar operation wavelength, and R represents the instantaneous oblique distance of radar, VNRepresent carrier aircraft north orientation speed, VERepresent carrier aircraft east orientation
Speed, VDCarrier aircraft ground is represented to speed, H represents the height of carrier aircraft relative target scene, and Θ represents the carrier aircraft angle of pitch, and α represents load
Machine flight-path angle, the λ is carried SAR systematic 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. the Real Time Image System of a kind of Ka wave bands carried SAR system according to claim 8, it is characterised in that described
Kinematic error compensation includes：A kinematic error being calculated according to inertial guidance data and secondary motion error to through distance to arteries and veins
Raw imaging data after punching press contracting, doppler centroid compensation, Azimuth Pre-filter and extraction treatment carries out kinematic error benefit
Repay.
10. the Real Time Image System of a kind of Ka wave bands carried SAR system according to claim 9, it is characterised 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 is processed, then carries out lateral displacement compensation deals, obtains output data, and the expression formula of the lateral displacement Δ x is：
Wherein, Δ x represents lateral displacement, fdcThe doppler centroid is represented, v represents carrier aircraft flying speed, and R represents radar
Instantaneous oblique distance, θ represents the carrier aircraft angle of pitch, the λ is carried SAR systematic 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) represents echo-signal frequency spectrum, and H (f) represents filter spectrum, and f represents Doppler frequency, the S (f)
Calculated by echo signal data, H (f) is calculated by carried SAR systematic parameter and inertial guidance data, the Doppler frequency
It is the variable that time-domain signal is converted into frequency domain signal.
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