CN103792536B - A kind of satellite-borne synthetic aperture radar slip beam bunching mode orientation is to parameter acquiring method - Google Patents

Abstract

The present invention provides a kind of satellite-borne synthetic aperture radar slip beam bunching mode orientation to parameter acquiring method, it is to utilize orientation to initial imaging belt length, antenna beamwidth, initial angle of strabismus, terminate angle of strabismus and build, with target oblique distance, the reference oblique distance model that wave beam center of rotation is corresponding, obtain and according to the effective irradiation time model corresponding with reference to one point target of oblique distance data construct, obtain and build effective Doppler frequency corresponding to this point target and doppler bandwidth model according to the most initial irradiation time of this point target with effectively terminating irradiation time, obtain and according to initial effective Doppler frequency corresponding to this point target, terminate effective Doppler frequency and doppler bandwidth, resolution descent coefficient builds the azimuth resolution model that this point target is corresponding, obtain the azimuth resolution that this point target is corresponding；Maximum orientation is then exported to imaging belt length data when azimuth resolution is more than resolution index request.

Description

A kind of satellite-borne synthetic aperture radar slip beam bunching mode orientation is to parameter acquiring method

Technical field

The invention belongs to satellite-borne synthetic aperture radar imaging field, relate to satellite-borne synthetic aperture radar (SAR) acquiring technology of systematic parameter.

Background technology

Satellite-borne synthetic aperture radar slip beam bunching mode is to study and realized high-resolution width in recent years to cover The Main Patterns of lid satellite-borne synthetic aperture radar imaging, and defended at Germany TerraSAR-X in 2007 Obtain imaging applications on star first, obtain a large amount of high-quality satellite-borne synthetic aperture radar image.But It is that TerraSAR-X is limited to scan capability due to antenna bearingt, its resolution and imaging belt length Index Design the highest (1m × 5km), by increasing scan capability and the power supply of satellite of antenna Ability, the performance of satellite-borne synthetic aperture radar slip beam bunching mode can be greatly improved that (resolution is excellent In 0.3m, imaging belt length is better than 10km).But performance raising can cause parameter designing, echo Signal simulation is greatly increased with imaging processing difficulty and complexity.

Satellite-borne synthetic aperture radar slip beam bunching mode distance is to the basic phase of parameter designing and band pattern With, but orientation is more complex to parameter designing.Satellite-borne synthetic aperture radar slip beam bunching mode side Position to parameter designing mainly to resolution, imaging belt length, orientation to beam angle, orientation to Initial angle of strabismus and orientation trade off analysis, to obtain work to terminating restriction relation between angle of strabismus The high-resolution width that can realize in journey cover diameter radar image azimuth resolution and orientation to Re-imaging length index.The parameter designing result the most accurately ground integrated echo-signal of star to be passed through Emulation, imaging processing and point target Performance Evaluation are verified, are better than 0.3m high-resolution spaceborne Synthetic aperture radar slip beam bunching mode echo simulation implements the most multiple with image-processing algorithms Miscellaneous, operand is big, the longest.Parameter designing process then can be when tentative programme designs accurately First avoid echo simulation and imaging process, and can ensure that parameter designing reliable results, carry The efficiency of high conceptual design.

The satellite-borne synthetic aperture radar slip beam bunching mode orientation occurred in the outer document of Present Domestic is to ginseng Number design processes are excessively simple, have following 2 deficiencies for engineer applied:

(1) calculate and time and the change relevant with Doppler frequency with single star ground relative velocity Amount, this approximation causes the calculated azimuth resolution of simple parameter and star ground integrated emulation knot Fruit differs greatly, and makes parameter designing result reliability reduce.

(2) orientation to antenna radiation pattern, imaging processing weighting, Doppler's parameter estimate error and becomes The azimuth resolution decline caused as algorithm approximation four factors does not has in relevant computing formula Embodying, discounting for the impact of these four factor, the resolution that simple parameter designing obtains exists Practical Project possibly cannot realize.

In satellite-borne SAR slip beam bunching mode engineering design process azimuth resolution with orientation to becoming Image-tape length is index request, user propose；Antenna bearingt to beam angle by radar operating wave Long and antenna bearingt determines to size, it is contemplated that the antenna length of satellite-borne synthetic aperture radar satellite is past Toward being determined by band pattern azimuth resolution, at this it is believed that orientation is known to antenna beamwidth； Antenna bearingt is determined to scan capability by antenna bearingt to initial and termination scan angle.In engineering, Making demands slip beam bunching mode orientation to antenna scanning ability is topmost design requirement.

Summary of the invention

(1) to solve the technical problem that

Complicated in order to solve prior art computing, length computationally intensive, time-consuming, inefficient defect, The purpose of the present invention is to propose to a kind of spaceborne slip beam bunching mode orientation of engineer applied that is applicable to one-tenth Image-tape Design of length flow process, can first avoid echo simulation and imaging processing when tentative programme designs Process, and can ensure that the reliable results that gets parms, improve efficiency getparms.

(2) technical scheme

In order to realize the purpose of the present invention, it is poly-that the present invention provides a kind of satellite-borne synthetic aperture radar to slide Bundle mode orientation is to parameter acquiring method, and it is as follows that the method comprising the steps of:

Step S1: set orientation to initial imaging belt length data, orientation to antenna beamwidth, Orientation to initial angle of strabismus data, orientation to terminating angle of strabismus data and target place oblique distance；

Step S2: utilize orientation to initial imaging belt length data, orientation to antenna beamwidth Data, orientation to initial angle of strabismus data, orientation to terminating angle of strabismus data and target oblique distance structure point The reference oblique distance model that wave beam center of rotation during target oblique distance is corresponding, it is thus achieved that during point target oblique distance The reference oblique distance data that wave beam center of rotation is corresponding；

Step S3: according to the reference oblique distance data that wave beam center of rotation during point target oblique distance is corresponding Building oblique distance is effective irradiation time model corresponding to the point target of R, it is thus achieved that this point target Effectively initial radiation time data and this point target effectively terminate radiation time data；

Step S4: building oblique distance according to the most initial described irradiation time and termination irradiation time is Effective Doppler Frequency Model corresponding to a point target and doppler bandwidth model, obtain this Initial effective doppler frequency data corresponding to point target, terminate effective doppler frequency data and many General Le band data；

Step S5: according to initial effective doppler frequency data and the effective Doppler frequency number of termination According to, the resolution descent coefficient that causes of doppler bandwidth data, antenna radiation pattern, imaging processing add Resolution descent coefficient that the resolution descent coefficient that causes of power, Doppler's parameter estimate error cause, It is corresponding that the resolution descent coefficient that imaging algorithm approximation causes builds the point target that oblique distance is R Azimuth resolution model, it is thus achieved that the azimuth resolution that this point target is corresponding；

Step S6: judge whether azimuth resolution meets less than resolution index request, if Show that orientation set in advance is less than normal to imaging belt length data, then perform step S1 and reset Orientation, to imaging belt length data value, repeats step S1～S5 until azimuth resolution is more than dividing Resolution index request, then the maximum orientation of output is to imaging belt length data.

(3) beneficial effect

The present invention provides satellite-borne synthetic aperture radar slip beam bunching mode certain to scan angle in orientation Under conditions of obtain the method for imaging belt length meeting resolution requirement, profit in this way can be straight Connect the orientation obtained to initial angle of strabismus, terminate angle of strabismus, beam angle, resolution and imaging belt Restriction relation between length, it is to avoid complicated echo simulation and imaging processing proof procedure, simplifies Satellite-borne synthetic aperture radar slip beam bunching mode conceptual design flow process, improves engineering design efficiency, tool Higher engineer applied is had to be worth.

Accompanying drawing explanation

Fig. 1 is satellite-borne synthetic aperture radar slip beam bunching mode operation principle rough schematic view.

Fig. 2 is that satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to imaging belt length Flow chart.

Detailed description of the invention

Below in conjunction with appended drawings 1 and Fig. 2, the present invention is described in detail.

The ultimate principle of satellite-borne SAR slip beam bunching mode is as it is shown in figure 1, at one section of imaging time In, satellite points to beam center with certain speed along orbital flight, control azimuth, makes orientation To beam center with certain initial angle of strabismus ψ_startStarting to rotate around rotary middle point, angle of strabismus reaches To terminating angle of strabismus ψ_endTime terminate.In engineering, rotary middle point is be under earth's surface Virtual point, the oblique distance that center of rotation is corresponding is more than the oblique distance at impact point place, on the ground, wave beam Center is moved from left to right, slips over all targets of imaging region successively, and in figure, middle heavy black is Imaging region.In Fig. 1, in imaging region, solid large circle point is any point target, and this point target is permissible It is in imaging region any position.Definition oblique distance is that any point target of R is in 3dB beam angle The interior time period is effective irradiation time, is in the moment of 3dB wave beam left side edge for initial effective Irradiate the moment, be in the moment of 3dB wave beam right side edge for terminating effectively irradiating the moment.To being in The point target echo data of different irradiation time sections carries out imaging processing, can obtain meeting certain resolution The point target image that rate requires.

In Fig. 1 and Fig. 2, each variable-definition is as follows:

ψ_startFor orientation to initial angle of strabismus, it is defined as orientation of Polaroid period in home beam The heart points to.

ψ_endFor orientation to terminating angle of strabismus, it is defined as orientation of Polaroid period to terminating in wave beam The heart points to.

θ_aFor orientation to beam angle, it is defined as antenna bearingt to transmitting-receiving equivalent directions figure half-power width Degree.

W_sceneFor orientation to imaging belt length, it is defined as orientation to the one-tenth meeting resolution index request As region.

R is point target oblique distance, and during being defined as imaging, radar is to the nearest oblique distance of target.

R_rotFor center of rotation oblique distance, during being defined as imaging, radar is to the nearest oblique distance of center of rotation.

X_pFor any point target imaging region location variable (relative to imaging region center, And to define imaging region center location variable be 0).

t_aFor the time variable of Polaroid period satellite position, definition distance by radar center of rotation is Moment time near is 0.

t_{A, start, 0}For the most initial irradiation time t that any point target is corresponding_{A, start, 0}, it is defined as at target In moment of beam angle left hand edge (relative to t_a=0)。

t_{A, end, 0}For effectively termination irradiation time t that any point target is corresponding_{A, end, 0}, it is defined as at target In moment of beam angle right hand edge (relative to t_a=0)。

ψ_{Start, 0}It is defined as any point target effective and initiates orientation corresponding to irradiation time to angle of strabismus.

ψ_{End, 0}It is defined as any point target effective and terminates orientation corresponding to irradiation time to angle of strabismus.

f_{A, start, 0}Initiate effective Doppler frequency for any point target, be defined as any point target and initiate The Doppler frequency that effectively irradiation time is corresponding.

f_{A, end, 0}For the effective Doppler frequency of any point target termination, it is defined as any point target termination The Doppler frequency that effectively irradiation time is corresponding.

f_dFor the doppler bandwidth that any point target is corresponding, it is defined as f_d=f_{A, start, 0}-f_{A, end, 0}。

ρ_aFor azimuth resolution.Resolution is defined as the orientation 3dB to point target impulse response Width.

k₁The resolution descent coefficient caused is weighted for antenna radiation pattern.

k₂The resolution descent coefficient caused for imaging processing weighting (for forcing down secondary lobe).

k₃The resolution descent coefficient caused for Doppler's parameter estimate error.

k₄The resolution descent coefficient caused is approximated for imaging algorithm.

k₁、k₂、k₃And k₄Being the parameter relevant with imaging performance, its value thinks known at this.

V_gFor wave beam ground speed (for scalar).

V_sFor satellite velocities (for scalar).

λ is the wavelength that synthetic aperture radar launches signal.

The echo samples initial time worked according to satellite orbit parameter and satellite-borne synthetic aperture radar, Satellite velocities V during the most a certain location point of satellite transit can be calculated_s, star ground relatively Speed V_gWith oblique distance R of target to radar, to V_s、V_gUsed with the calculating process of R, recognized at this For known.

In orientation to angle of strabismus ψ_start, angle of strabismus ψ_endWith 3dB beam angle θ_aUnder conditions of Yi Ding, Obtain orientation as follows to the calculation procedure of the maximum imaging belt length meeting resolution requirement:

Step S1: set orientation to initial imaging belt length data W_scene, orientation is to antenna beam Width θ_a, orientation is to initial angle of strabismus data ψ_start, orientation is to terminating angle of strabismus data ψ_endAnd mesh Mark place oblique distance R；

Step S2: according to geometrical relationship between target and radar during satellite flight, utilizes Orientation is to initial imaging belt length data W_scene, orientation is to antenna 3dB beam angle data θ_a, side Position is to initial angle of strabismus data ψ_start, orientation is to terminating angle of strabismus data and target oblique distance R ψ_end, Build reference oblique distance R that when point target oblique distance is R, wave beam center of rotation is corresponding_rot, computing formula is such as Under:

$R_{\mathrm{rot}}=\frac{R\·[\tan ({\mathrm{\ψ}}_{\mathrm{end}}+{\mathrm{\θ}}_a/2)-\tan ({\mathrm{\ψ}}_{\mathrm{start}}-{\mathrm{\θ}}_a/2)]-W_{\mathrm{scene}}}{[\tan \left({\mathrm{\ψ}}_{\mathrm{end}}\right)-\tan \left({\mathrm{\ψ}}_{\mathrm{start}}\right)]}---\left(1\right)$

Step S3: according to the reference oblique distance data that wave beam center of rotation during point target oblique distance R is corresponding Building oblique distance is effective irradiation time model corresponding to the point target of R, it is thus achieved that this point target Effectively initial radiation time data t_{A, start, 0}With this point target effectively terminate radiation time data t_{A, end, 0}；Calculating oblique distance is the most initial irradiation time t corresponding to the point target of R_{A, start, 0}And end Only irradiation time t_{A, end, 0}, computing formula is as follows:

$\begin{array}{c}\left\{\begin{array}{c}\frac{V_g\·t_{a,\mathrm{start},0}}{R_{\mathrm{rot}}}=\tan \left({\mathrm{\ψ}}_{\mathrm{start},0}\right)\\ \frac{V_g\·t_{a,\mathrm{start},0}-X_p}{R_{\mathrm{rot}}}=\tan ({\mathrm{\ψ}}_{\mathrm{start},0}-{\mathrm{\θ}}_a/2)\end{array}\right.\\ \⇒\tan \left({\mathrm{\ψ}}_{\mathrm{start},0}\right)=\frac{X_p}{2\·R_{\mathrm{rot}}}+\frac{R/R_{\mathrm{rot}}-1}{2\·\tan ({\mathrm{\θ}}_a/2)}+\sqrt{{[\frac{X_p}{2\·R_{\mathrm{rot}}}+\frac{R/R_{\mathrm{rot}}-1}{2\·\tan ({\mathrm{\θ}}_a/2)}]}^2-\frac{R}{R_{\mathrm{rot}}}+\frac{X_p}{R_{\mathrm{rot}}\·\tan ({\mathrm{\θ}}_a/2)}}\\ \⇒t_{a,\mathrm{start},0}=\frac{R_{\mathrm{rot}}\·\tan \left({\mathrm{\ψ}}_{\mathrm{start},0}\right)}{V_g}\end{array}---\left(2\right)$

$\begin{array}{c}\left\{\begin{array}{c}\frac{V_g\·t_{a,\mathrm{end},0}}{R_{\mathrm{rot}}}=\tan \left({\mathrm{\ψ}}_{\mathrm{end},0}\right)\\ \frac{V_g\·t_{a,\mathrm{end},0}-X_p}{R_{\mathrm{rot}}}=\tan ({\mathrm{\ψ}}_{\mathrm{end},0}+{\mathrm{\θ}}_a/2)\end{array}\right.\\ \⇒\tan \left({\mathrm{\ψ}}_{\mathrm{end},0}\right)=\frac{X_p}{2\·R_{\mathrm{rot}}}+\frac{1-R/R_{\mathrm{rot}}}{2\·\tan ({\mathrm{\θ}}_a/2)}+\sqrt{{[\frac{X_p}{2\·R_{\mathrm{rot}}}+\frac{1-R/R_{\mathrm{rot}}}{2\·\tan ({\mathrm{\θ}}_a/2)}]}^2-\frac{R}{R_{\mathrm{rot}}}+\frac{X_p}{R_{\mathrm{rot}}\·\tan ({\mathrm{\θ}}_a/2)}}\\ \⇒t_{a,\mathrm{end},0}=\frac{R_{\mathrm{rot}}\·\tan \left({\mathrm{\ψ}}_{\mathrm{end},0}\right)}{V_g}\end{array}---\left(3\right)$

Wherein: this point target is in location variable X of imaging region_pIt is expressed asSolve equation (2) and obtain t_{A, start, 0}Data, solve equation (3) and obtain t_{A, end, 0} Data.

In the present invention, point target effectively initiates irradiation time and uses star in the calculating terminating irradiation time Ground ground velocity relatively, makes the calculating about the time the most accurate.General document uses star ground relatively The speed approximate calculation time, introduce bigger deviation.

Step S4: according to the most initial described irradiation time t_{A, start, 0}With termination irradiation time t_{A, end, 0}Structure Build effective Doppler Frequency Model corresponding to a point target that oblique distance is R and doppler bandwidth mould Type, obtains initial effective doppler frequency data f that this point target is corresponding_{A, start, 0}, terminate effectively Doppler frequency data f_{A, end, 0}With doppler bandwidth data f_d；Calculate corresponding the rising of any point target Begin effective Doppler frequency f_{A, start, 0}With effective Doppler frequency f of termination_{A, end, 0}With doppler bandwidth f_d。

$f_{a,\mathrm{start},0}=-\frac{2\·V_s}{\mathrm{\λ}}\·\sin ({\mathrm{\ψ}}_{\mathrm{start},0}-{\mathrm{\θ}}_a/2)=-\frac{2\·V_s}{\mathrm{\λ}}\·\frac{V_g\·t_{a,\mathrm{start},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{start},0}-X_p)}^2}}---\left(4\right)$

$f_{a,\mathrm{end},0}=-\frac{2\·V_s}{\mathrm{\λ}}\·\sin ({\mathrm{\ψ}}_{\mathrm{start},0}+{\mathrm{\θ}}_a/2)=-\frac{2\·V_s}{\mathrm{\λ}}\·\frac{V_g\·t_{a,\mathrm{end},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{end},0}-X_p)}^2}}---\left(5\right)$

$\begin{array}{c}{f}_d=f_{a,\mathrm{start},0}-f_{a,\mathrm{end},0}\\ =-\frac{2\·V_s}{\mathrm{\λ}}[\frac{V_g\·t_{a,\mathrm{start},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{start},0}-X_p)}^2}}-\frac{V_g\·t_{a,\mathrm{end},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{end},0}-X_p)}^2}}]\end{array}---\left(6\right)$

Initial effective Doppler frequency and the effective Doppler frequency of termination that point target is corresponding calculate and use The speed of satellite, makes the calculating about Doppler frequency more accurate.General document uses star ground Relative velocity approximate calculation Doppler frequency, introduces bigger deviation.

Step S5: according to initial effective doppler frequency data f_{A, start, 0}With termination effective Doppler frequency Rate data f_{A, end, 0}, doppler bandwidth data f_d, the resolution descent coefficient k that causes of antenna radiation pattern₁、 Imaging processing weights the resolution descent coefficient k caused₂, Doppler's parameter estimate error cause point Resolution descent coefficient k₃, imaging algorithm approximate the resolution descent coefficient k that causes₄Structure oblique distance is R Azimuth resolution model corresponding to a point target, it is thus achieved that orientation corresponding to this point target to Resolution；Simplify geometric model according to satellite-borne synthetic aperture radar slip beam bunching mode, calculate acquisition side Position oblique distance in imaging belt is the azimuth resolution that any point target of R is corresponding, is simultaneously introduced sky The weighting of line directional diagram, imaging processing, Doppler's parameter estimate error and imaging algorithm approximation cause Azimuth resolution broadening.Described azimuth resolution model ρ_aIt is expressed as follows:

$\begin{array}{c}{\mathrm{\ρ}}_a=k_1\·k_2\·k_3\·k_4\·\frac{V_g}{f_d}\\ =-k_1\·k_2\·k_3\·k_4\·\frac{\mathrm{\λ}\·V_g}{2\·V_s}{[\frac{V_g\·t_{a,\mathrm{start},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{start},0}-X_p)}^2}}-\frac{V_g\·t_{a,\mathrm{start},0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,\mathrm{end},0}-X_p)}^2}}]}^{-1}\end{array}---\left(7\right)$

It is to set satellite in a period of time that described satellite-borne SAR slip beam bunching mode simplifies geometric model Flight path is approximately straight line, and point target is static target；During imaging, control azimuth refers to wave beam To, make beam center point to a virtual point below away from imaging region, described virtual point all the time Being wave beam center of rotation, virtual point is in below ground；Wave beam the most slowly slips over imaging area Territory W_Xscene, in imaging region, oblique distance is that point target X of R goes through 3dB beam angle, from direction Figure right side edge enters into left side edge and leaves, initiateing during point target approach axis figure right side edge Angle of strabismus is ψ_{Start, 0}, termination angle of strabismus during point target departure direction figure left side edge is ψ_{End, 0}.Institute State orientation to initial angle of strabismus data ψ_startWith orientation to terminating angle of strabismus data ψ_endSize and just Negative not restriction, therefore, it is adaptable to positive side-looking satellite-borne SAR slip beam bunching mode, is also applied for Stravismus satellite-borne SAR slip beam bunching mode.

In the present invention, azimuth resolution corresponding to point target calculates and introduces what antenna radiation pattern caused Azimuth resolution descent coefficient k₁, imaging processing weight the azimuth resolution descent coefficient that causes k₂, the azimuth resolution descent coefficient k that causes of Doppler's parameter estimate error₃, and imaging algorithm The azimuth resolution descent coefficient k that approximation causes₄.In engineering, it is better than 0.5 meter in resolution Spaceborne slip beam bunching mode in, it is must that point target azimuth resolution that these four factor causes declines The design content that need consider, otherwise, the resolution of point target image, peak sidelobe ratio and integration Secondary lobe does not reaches index request than design load.General document is not the most mentioned these four factor pair Orientation is to the combined influence of imaging performance.But these four factor is respectively to satellite-borne SAR image performance Analysis process and the influence degree size of impact are not belonging to present disclosure.

Step S6: judge azimuth resolution ρ_aWhether meet less than index request, if orientation To resolution ρ_aMeet less than resolution index request, show that orientation set in advance is to imaging belt length Degree W_sceneLess than normal, then perform step S1 and reset orientation to imaging belt length data W_sceneValue, Then step S2～S5 are repeated, until ρ_aMore than resolution index request, then orientation is to imaging belt Length reaches maximum.Loop iteration method is utilized to meet orientation to resolution when determining target oblique distance for R The maximum imaging belt length that rate requires.

Need to provide following 2 explanations at this:

(1) oblique distance be the point target of R in orientation when the difference of position resolution be slightly changed, ginseng Number design result to ensure that worst resolution meets index request.

(2) the calculation method of parameters derivation of the present invention there is a precondition, it is simply that false During being located at imaging, satellite flight track is approximately straight line.If imaging time is long, satellite flies Row track can not be approximately straight line, then the parameter utilizing the method for the invention to obtain has certain journey The deviation of degree.The method of the invention can ensure to set in the case of meeting three below condition at the same time The accuracy of meter parameter: first, orientation is not less than 0.4 ° to beam angle；Second, orientation is to one-tenth Image-tape length is not more than 15 kilometers；Azimuth resolution is more than or equal to 0.3 meter.The most at present and not In coming 10 years from the point of view of the Development Trends of satellite-borne synthetic aperture slip beam bunching mode, in engineering Attainable spaceborne synthetic aperture radar (SAR) system meets three above condition the most simultaneously, therefore, and this Bright content has higher engineer applied and is worth.

Claims (10)

1. satellite-borne synthetic aperture radar slip beam bunching mode orientation is to a parameter acquiring method, and it is special Levy and be to comprise the following steps that

Step S1: set orientation to initial imaging belt length data, orientation to antenna beamwidth, Orientation to initial angle of strabismus data, orientation to terminating angle of strabismus data and target place oblique distance；

Step S2: utilize orientation to initial imaging belt length data, orientation to antenna beamwidth Data, orientation build to termination angle of strabismus data and target oblique distance to initial angle of strabismus data, orientation The reference oblique distance model that wave beam center of rotation during point target oblique distance is corresponding, it is thus achieved that during point target oblique distance Reference oblique distance data corresponding to wave beam center of rotation；

Step S3: according to the reference oblique distance data that wave beam center of rotation during point target oblique distance R is corresponding Build effective irradiation time model that a point target of oblique distance R is corresponding, it is thus achieved that this point target Effectively initial radiation time data and this point target effectively terminate radiation time data；

Step S4: building oblique distance according to the most initial described irradiation time and termination irradiation time is R Effective Doppler Frequency Model corresponding to a point target and doppler bandwidth model, obtain this Initial effective doppler frequency data corresponding to point target, terminate effective doppler frequency data and many General Le band data；

Step S5: according to initial effective doppler frequency data and the effective Doppler frequency number of termination According to, the resolution descent coefficient that causes of doppler bandwidth data, antenna radiation pattern, imaging processing add Resolution descent coefficient that the resolution descent coefficient that causes of power, Doppler's parameter estimate error cause, It is corresponding that the resolution descent coefficient that imaging algorithm approximation causes builds the point target that oblique distance is R Azimuth resolution model, it is thus achieved that the azimuth resolution that this point target is corresponding；

Step S6: judge whether azimuth resolution meets less than resolution index request, if Show that orientation set in advance is less than normal to imaging belt length data, then perform step S1 and reset Orientation, to imaging belt length data value, repeats step S1～S5 until azimuth resolution is more than dividing Resolution index request, then the maximum orientation of output is to imaging belt length data.

2. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that described point target oblique distance is the ginseng that wave beam center of rotation during R is corresponding Examine oblique distance model R_rotIt is expressed as follows:

$R_{rot}=\frac{R\·\[tan({\mathrm{\ψ}}_{end}+{\mathrm{\θ}}_a/2)-tan({\mathrm{\ψ}}_{start}-{\mathrm{\θ}}_a/2)\]-W_{scene}}{\[tan\left({\mathrm{\ψ}}_{end}\right)-tan\left({\mathrm{\ψ}}_{start}\right)\]}---\left(1\right)$

Wherein: ψ_endFor orientation to terminating angle of strabismus data, θ_aFor orientation to antenna beam width degrees of data, ψ_startFor orientation to initial angle of strabismus data, W_sceneFor orientation to initial imaging belt length data.

3. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that described oblique distance is effective irradiation time that the point target of R is corresponding Model includes effectively initiateing irradiation time model t_{A, start, 0}With effectively termination irradiation time model t_{A, end, 0}, Solve t_{A, start, 0}And t_{A, end, 0}Equation group be expressed as follows respectively:

$\left\{\begin{array}{c}\frac{V_g\·t_{a,start,0}}{R_{rot}}=tan\left({\mathrm{\ψ}}_{start,0}\right)\\ \frac{V_g\·t_{a,start,0}-X_p}{R_{rot}}=tan({\mathrm{\ψ}}_{start,0}-{\mathrm{\θ}}_a/2)\end{array}\right.---\left(2\right)$

$\left\{\begin{array}{c}\frac{V_g\·t_{a,end,0}}{R_{rot}}=tan\left({\mathrm{\ψ}}_{end,0}\right)\\ \frac{V_g\·t_{a,end,0}-X_p}{R_{rot}}=tan({\mathrm{\ψ}}_{end,0}+{\mathrm{\θ}}_a/2)\end{array}\right.---\left(3\right)$

Wherein: V_gFor wave beam ground speed, ψ_{Start, 0}Irradiation time is initiateed corresponding for this point target effective Orientation to angle of strabismus, X_pFor this point target in the location variable of imaging region,θ_aFor orientation to beam angle, R_rotFor center of rotation oblique distance, ψ_{End, 0}Fixed Justice effectively terminates orientation corresponding to irradiation time to angle of strabismus for this point target；Solve equation (2) to obtain Obtain t_{A, start, 0}Data, solve equation (3) and obtain t_{A, end, 0}Data.

4. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that described oblique distance is effective Doppler frequency that the point target of R is corresponding Rate model includes initial effective Doppler frequency that this point target is corresponding with doppler bandwidth model Model f_{A, start, 0}, terminate effective Doppler frequency f_{A, end, 0}Model, wherein:

$f_{a,start,0}=-\frac{2\·V_s}{\mathrm{\λ}}\·sin({\mathrm{\ψ}}_{start,0}-{\mathrm{\θ}}_a/2)=-\frac{2\·V_s}{\mathrm{\λ}}\·\frac{V_g\·t_{a,start,0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,start,0}-X_p)}^2}}---\left(4\right)$

$f_{a,end,0}=-\frac{2\·V_s}{\mathrm{\λ}}\·sin({\mathrm{\ψ}}_{end,0}+{\mathrm{\θ}}_a/2)=-\frac{2\·V_s}{\mathrm{\λ}}\·\frac{V_g\·t_{a,end,0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,end,0}-X_p)}^2}}---\left(5\right)$

Wherein: V_sIt is that synthetic aperture radar launches the wavelength of signal, ψ for satellite velocities, λ_{Start, 0}For oblique distance For the point target of R effectively initiate orientation corresponding to irradiation time to angle of strabismus, θ_aFor orientation to Beam angle, V_gFor wave beam ground speed, t_{A, start, 0}For the most initial irradiation that this point target is corresponding Time, X_pFor this point target in the location variable of imaging region,R is Point target oblique distance, ψ_{End, 0}It is defined as this point target effective and terminates orientation corresponding to irradiation time to tiltedly Visual angle, t_{A, end, 0}For this point target corresponding effectively terminate irradiation time.

5. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 4 Access method, it is characterised in that described oblique distance is the doppler bandwidth mould that the point target of R is corresponding Type is expressed as follows:

$\begin{array}{c}{f}_d=f_{a,start,0}-f_{a,end,0}\\ =-\frac{2\·V_s}{\mathrm{\λ}}\[\frac{V_g\·t_{a,start,0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,start,0}-X_p)}^2}}-\frac{V_g\·t_{a,end,0}-X_p}{\sqrt{R^2+{(V_g\·t_{a,end,0}-X_p)}^2}}\]\end{array}---\left(6\right)$

Wherein: V_sIt is that synthetic aperture radar launches the wavelength of signal, V for satellite velocities, λ_gFor wave beam ground Face velocity, t_{A, start, 0}For the most initial irradiation time, X that the point target that oblique distance is R is corresponding_pFor This point target in the location variable of imaging region,R is this point mesh Mark oblique distance, t_{A, end, 0}For this point target corresponding effectively terminate irradiation time.

6. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that described azimuth resolution model ρ_aIt is expressed as follows:

${\mathrm{\ρ}}_a=k_1\·k_2\·k_3\·k_4\·\frac{V_g}{f_d}---\left(7\right)$

Wherein: k₁The resolution descent coefficient that causes for antenna radiation pattern, k₂Cause for imaging processing weighting Resolution descent coefficient, k₃The resolution descent coefficient that causes for Doppler's parameter estimate error, k₄ Resolution descent coefficient, the f caused is approximated for imaging algorithm_dFor the point target pair that oblique distance is R The doppler bandwidth answered, V_gFor wave beam ground speed.

7. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that simplify geometry mould according to satellite-borne synthetic aperture radar slip beam bunching mode Type obtains the azimuth resolution of any point target that orientation oblique distance in imaging belt is R.

8. satellite-borne synthetic aperture radar slip beam bunching mode orientation obtains to parameter as claimed in claim 1 Access method, it is characterised in that utilize loop iteration method to meet orientation when determining target oblique distance for R To the maximum imaging belt length of resolution requirement.

9. satellite-borne synthetic aperture radar slip beam bunching mode orientation as claimed in claim 1 is to parameter Acquisition methods, it is characterised in that in setting a period of time, satellite flight track is approximately straight line, point Target is static target；During imaging, control azimuth is to beam position, makes beam center point to all the time Away from a virtual point below imaging region, described virtual point is wave beam center of rotation, virtual point It is in below ground；Wave beam the most slowly slips over imaging region, and in imaging region, oblique distance is R Point target go through 3dB beam angle, enter into left side edge from directional diagram right side edge and leave, Initial angle of strabismus during point target approach axis figure right side edge, point target departure direction figure left side Termination angle of strabismus during edge.

10. satellite-borne synthetic aperture radar slip beam bunching mode orientation as claimed in claim 1 is to parameter Acquisition methods, it is characterised in that described orientation is looked side ways to termination to initial angle of strabismus data and orientation The size of angular data and positive and negative not restriction, therefore, it is adaptable to positive side-looking satellite-borne SAR slides poly- Bundle pattern, is also applied for looking side ways satellite-borne SAR slip beam bunching mode.