CN102322849A - Pretreatment method of real-time transmission tasks - Google Patents

Abstract

The invention relates to a pretreatment method of real-time transmission tasks. First, time zones in which a ground target is visible to a satellite are calculated, and tasks when there is no visible time window or when the time window is in the earth shadow are rejected. Then, time zones in which a ground station and the satellite can communicate are determined, time zones in which real-time transmissions of the tasks can be carried out by the satellite are determined, and tasks without a real-time transmission zone are rejected. Factors influencing graph qualities are determined, imaging quality determination functions are established, and tasks which can not satisfy the imaging quality requirements are rejected. Clipping is carried out upon the real-time transmission zone of each left task, such that task execution time windows satisfying the imaging quality requirements are obtained. Meanwhile, according to the attitude angle of the satellite pointing at the target at each time point during a task execution procedure, the observation duration of the task is calculated. When the observation duration of the task is in the task execution time window, the task is considered as an executable task. All executable tasks are submitted to a satellite task planning system, and are subject to task planning and task scheduling.

Description

A kind of preprocess method to real biography task

Technical field

The invention belongs to satellite mission planning and scheduling field, relate in a kind of satellite mission planning process preprocess method the real-time Transmission task.

Background technology

The motor-driven imaging satellite of rapid posture can be realized multiple complicated imaging pattern by the rapid posture maneuverability.Compare with the traditional earth observation satellite that adopts the substar imaging, the rapid posture maneuverability has increased the observation airplane meeting of satellite to target greatly, thereby has stronger observing capacity.Each imaging pattern of the motor-driven imaging satellite of rapid posture all is accompanied by operations such as a plurality of attitude maneuvers, camera switch machine, and these operations form the steering order sequence that front and back link up.Because instruction is various, therefore the real-time problem that can't guarantee to instruct reliability and the instruction of layout and last notes to carry out must set up a cover mission planning and a dispatching system, accomplishes the automated analysis and the processing of observation mission in enormous quantities.

Real biography task is a generic task more special in the satellite earth observation task, need be at the same picture of blit at present that forms images, and be the key link of the motor-driven imaging satellite mission planning of rapid posture to the pre-service of real biography task.Seldom mention pre-service in the existing mission planning method to real biography task; And in the calculating of time window, there is certain defective; Rolled up " exploitation of satellite whole world generaI investigation mission planning system pre-processing module " delivered on 7 phases " Computer Simulation " at 2006 the 23rd like Liu Xiong; Li Xi is in its master's thesis " the efficiency optimization method research of many constellations territory observation mission ", and Li Jufang has mentioned the method that adopts the visible time window of STK computed in software in its doctor's thesis " many land stations of the many stars of space reconnaissance mission planning Study on Problems "; Its basic step is a constructive simulation scene in STK software; Set up artificial physicals such as satellite, terrain object and sensor, parameters such as satellite orbit, sensor field of view are set, can pass through sensor and target data.This method realizes simple; In satellite mission planning method research and software product, obtained widespread use, still, carried out the task pre-service based on STK software; Can make final Optimization result receive the influence of STK software; The error of STK software also inevitably can be brought in the final Optimization result, and this method do not consider the variation of different observation condition hypograph quality, the degradation problem under the resolution of image when excessive like satellite side-sway angle or the angle of pitch.

The motor-driven imaging satellite of rapid posture is owing to possess wide-angle attitude maneuver ability; There is very big-difference in image quality when same section visible time interval adopts different attitude angle that same target is observed, so this method is inapplicable to the motor-driven imaging satellite of rapid posture.In addition, in the task planning system, hope real biography task is carried out certain pre-service; Eliminate its singularity, make it to adopt same treatment scheme, to simplify procedures with other tasks; And not needing problems such as whether other consideration can pass in fact, prior art can't satisfy this type demand.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome the deficiency of prior art, a kind of preprocess method to real biography task of highly versatile is provided.

Technical solution of the present invention is: a kind of preprocess method to real biography task, and step is following:

(1) according to the camera fabric width mission area band is divided;

(2) confirm the visible time interval [t of satellite according to the maximum angle of pitch of satellite and maximum roll angle and task stripe information to each band ₀', t _n'], reject visible time window of nothing and time window task in the shadow zone, ground; Visible time interval [the t of each band ₀', t _n'] by the visible time interval [t of satellite to these four summits of band ₁, t ₂] _k, k=1,2,3,4 seek common ground and reject behind the time interval in shadow zone, ground obtains; Satellite is confirmed by the maximum angle of pitch and the maximum roll angle of satellite the visible time interval on the single summit of band;

(3) according to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn];

(4) according to step (3) but the interval [t of the call duration time that obtains _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, confirm that satellite can carry out the real time interval [t that passes to task ₀, t _n], rejecting does not exist can pass interval task in fact;

(5) with modulation transfer function MTF, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction be as the principal element that influences picture quality, in step (4) but the interval [t of the call duration time of confirming ₀, t _n] in picture quality is expressed as the function of a single variable R (t) of time,

R(t)＝η _MTFR _MTF+η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _snrR _snr(t)+η _breathR _breath(t)，

η in the formula _MTF+ η _GSDx+ η _GSDy+ η _Snr+ η _Breath=1, R _MTF, R _GSDx(t), R _GSDy(t), R _Snr(t), R _Breath(t) be respectively modulation transfer function MTF, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction and the function of a single variable of time relation;

(6) the function of a single variable expression formula that adopts step (5) to obtain calculate respectively in step (4), confirm can pass time interval [t in fact ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of interval image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m);

(7) the minimum permission image quality of note is R _p, with R _pThe R that obtains with step (6) ₀, R _n, R _MaxCompare, set the tasks satisfy that image quality requires can pass interval [t in fact ₁, t ₂], reject and do not satisfy the task that image quality requires;

(8) adopt the flat-sawn method to calculate the observation duration T of each task band _Last, T _LastBegin to finish time of being continued to the summit of the last observation of this band for the summit of observing at first from this band; Observation duration T when the task band _LastDuring less than the task observation window time interval length of step (7), this task be for executing the task, and all can be executed the task submit to the mission planning system and carry out mission planning and scheduling.

The present invention's advantage compared with prior art is:

(1) but the present invention according to the call duration time of earth station and satellite and user's image quality requirement; Real biography task has been carried out Preliminary screening; Rejected the task of " not having visible time window ", " not satisfying image quality requires ", " time window is in the shadow zone, ground ", " do not exist and to pass the interval in fact ", " not satisfying the observation duration "; Reached and cut down the decision-making quantity of mission planning problem and the purpose of feasible zone; Reduced the complexity of problem; And eliminated the particularity of real biography task, made it to adopt same mission planning to handle flow process with other tasks;

(2) in the task with traditional planning problem, all target is reduced to point target, sets unified, the less observation duration to guarantee to obtain the terrain object image of appointment; The motor-driven imaging satellite of rapid posture is owing to possess multiple complicated imaging pattern; There is very big-difference in the target sizes that faces; And attitude maneuver is frequent between the task; Consumed time has nothing in common with each other, and sets the unified observation duration, will influence its dynamical advantage of the motor-driven imaging satellite performance of rapid posture.The inventive method is based on the particular location of observed object; Through confirming the time of the corresponding substar of real biography task; Obtain the observation time started and the concluding time of task, calculate the more accurate observation duration, to satisfy the needs of the motor-driven imaging satellite mission planning of rapid posture;

(3) the present invention is with the foundation of image quality as time window calculating; Main dynamic indicator to influencing picture quality is taken all factors into consideration; For different surface attribute and observation requirements, can different observed objects be treated with a certain discrimination through parameters such as adjustment weight, earth surface reflection rates; Adapt to the cutting of different observed object time window and require diversified demand; Can satisfy the needs of the motor-driven imaging satellite mission planning of rapid posture, and image quality computing function and the decoupling zero of time window method of cutting out, good versatility and dirigibility had;

(4) the inventive method adopts the flat-sawn method as finding the solution the observation duration of task and the core algorithm of minimum permission image quality equation; Not only can obtain the numerical solution of arbitrary accuracy; And iterations is less; Computing velocity is fast, can satisfy the constraint of extensive optimization problem for the algorithm time complexity.

Description of drawings

Fig. 1 is the FB(flow block) of the inventive method;

Fig. 2 is the visible time window calculation flow chart of the present invention;

Fig. 3 is a fabric width computing formula derivation synoptic diagram of the present invention;

Fig. 4 can pass interval [t in fact for task 2 in the embodiment of the invention ₀, t _n] the interior situation of change synoptic diagram of observing the angle of pitch;

Fig. 5 can pass interval [t in fact for task 2 in the embodiment of the invention ₀, t _n] the interior situation of change synoptic diagram of observing roll angle;

Fig. 6 can pass interval [t in fact for task 2 in the embodiment of the invention ₀, t _n] the situation of change synoptic diagram of interior sun altitude;

Fig. 7 can pass interval [t in fact for task 2 in the embodiment of the invention ₀, t _n] the situation of change synoptic diagram of interior image quality.

Embodiment

As shown in Figure 1, the flow process of passing round for a look the preprocess method of survey task during the motor-driven imaging satellite of rapid posture of the present invention comprises: 1. the mission area band is divided; 2. calculate the position and the speed of satellite; 3. calculate the visible time interval of satellite to each task band; 4. but the call duration time that calculates land station and satellite is interval; 5. calculate satellite and can carry out the real time interval that passes task; 6. the structure imaging quality is confirmed function; 7. the existence of judgement time window; 8. adopt flat-sawn method cutting time window; 9. confirm the observation duration; 10. output is to the pretreatment information of each real biography task.Describe in detail respectively below:

One, the mission area band is divided

Usually, the longitude and latitude on a plurality of summits of observation mission zone passage is described, and these summits is connected successively promptly obtain mission area.Among the present invention, adopt following method that mission area is divided into the band that is parallel to satellite orbit, be convenient to satellite and implement observation:

1. from satellite star roll off the production line, be width, do the parallel lines that star rolls off the production line, until covering mission area with substar camera fabric width (the satellite side-sway angle is 0 o'clock a camera fabric width); It is the set of substar (the vertical projection point that satellite position point is gone up at the earth's surface) that star rolls off the production line;

2. do the vertical line that the satellite star rolls off the production line from each summit of mission area, and calculate the distance between the intersection point, two intersection points that distance is grown most between the note intersection point are respectively L1 and L2, and the mission area summit corresponding with L1 is D1, and the mission area summit corresponding with L2 is D2;

3. connect L1 and D1 respectively, L2 and D2 obtain and the roll off the production line intersection point of parallel lines of step 1 culminant star, constitute tetragonal 4 intersection points and promptly form a task band, thus mission area are divided;

4. select to cover fully one or more task bands of mission area, as the elementary cell of mission planning and scheduling.

Two, calculate the position and the speed of satellite

The method that employing is found the solution dynamics of orbits equation numerical integration is forecast orbital position and the speed of satellite under the J2000 inertial coordinates system in the limiting time section.

According to the orbital tracking of satellite, can extrapolate the orbital position R under the mission planning initial time J2000 inertial coordinates system _SatWith speed V _Sat, adopt the Cowell method to find the solution dynamics of orbits equation (selecting Gauss perturbed motion equation for use) again, obtain the orbital position R of satellite under the J2000 inertial coordinates system in the limiting time section _SatWith speed V _SatGauss perturbed motion equation and Cowell method have detailed explanation in " spacecraft orbit is theoretical " (Liu Linzhu, 2000) book that National Defense Industry Press publishes.The J2000 inertial coordinates system defines the document that sees reference " coordinate system additional perturbation and reference frame are selected problem in the earth satellite motion " (" space science journal " 2008 the 28th the 2nd phases of volume, author Liu Lin, Tang Jingshi).

Three, calculate the visible time interval of satellite to each task band

To each band, the orbital position R that obtains according to above-mentioned second portion _SatWith speed V _SatCalculate the attitude angle that each discrete moment point satellite points to each band summit, according to attitude of satellite maneuvering range each discrete moment point is traveled through again, obtain the visible time window of each band; According to the result of calculation of target sun altitude, reject observation window at last in the shadow zone, ground.The example that is calculated as with a band describes below.

1. according to the orbital position R under the J2000 coordinate system _SatWith speed V _Sat, calculate the attitude angle on each each summit of moment point satellite sensing band in the limiting time section.Only describe below with the example that is calculated as of a point.

The orbital position R of known satellite _Sat, speed V _Sat, the earth longitude and latitude of terrain object point And Coordinated Universal Time(UTC) UTC time t.At first, calculate the t position vector R of impact point under the J2000 inertial coordinates system constantly according to the earth longitude and latitude of impact point _{T, f}(t), then according to R _{T, f}(t) with satellite t position vector R constantly _Sat, obtain the attitude angle that t moment satellite points to this impact point.Concrete steps are following:

Terrain object is put the earth longitude and latitude to be converted into the earth's core longitude and latitude

computing formula and to be:

λ _c＝λ _d，

Wherein representes compression of the earth, calculates impact point the earth's core distance then:

R _e=6378.140km is the terrestrial equator radius.

Be tied to the transition matrix R of J2000 inertial coordinates system according to UTC Time Calculation body-fixed coordinate system _If(t), computing method have detailed description in " spacecraft orbit is theoretical " (Liu Linzhu, 2000) that National Defense Industry Press publishes.Through coordinate transform, obtain the position vector of impact point under the J2000 inertial coordinates system:

R _x(α), R _y(α), R _z(α) represent primitive transformation matrix respectively around x, y, the rotation of z axle:

$R_x\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\α}& \sin \mathrm{\α}\\ 0& -\sin \mathrm{\α}& \cos \mathrm{\α}\end{array}\right]$

$R_y\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}\cos \mathrm{\α}& 0& -\sin \mathrm{\α}\\ 0& 1& 0\\ \sin \mathrm{\α}& 0& \cos \mathrm{\α}\end{array}\right]$

$R_z\left(\mathrm{\α}\right)=\left[\begin{array}{ccc}\cos \mathrm{\α}& \sin \mathrm{\α}& 0\\ -\sin \mathrm{\α}& \cos \mathrm{\α}& 0\\ 0& 0& 1\end{array}\right]$

Calculate the vector of satellite directed towards ground impact point under the J2000 inertial coordinates system then:

R _f(t)＝R _T，f(t)-R _sat

With vector R _f(t) transform to the satellite orbit coordinate system by the J2000 inertial coordinates system:

$R_o\left(t\right)=R_{\mathrm{oi}}{R}_f\left(t\right)=\left(\begin{array}{c}{v}_x\left(t\right)\\ v_y\left(t\right)\\ v_z\left(t\right)\end{array}\right)$

Wherein, R _OiExpression J2000 inertial coordinate is tied to the transition matrix of satellite orbit coordinate system.Above-mentioned body-fixed coordinate system definition, the definition of satellite orbit coordinate system and J2000 inertial coordinate are tied to the conversion derivation of satellite orbit coordinate system and see " satellite orbit and attitude dynamics and control " (Zhang Renwei writes, 1998) that publishing house of BJ University of Aeronautics & Astronautics publishes.

Crab angle is 0 o'clock; According to geometric relationship between the attitude Eulerian angle, obtain the observation attitude angle

(change preface be 312) of satellite to target:

$\left[\begin{array}{c}\mathrm{yaw}\left(t\right)\\ \mathrm{roll}\left(t\right)\\ \mathrm{pitch}\left(t\right)\end{array}\right]=\left[\begin{array}{c}0\\ \arcsin \left(\frac{v_x\left(t\right)}{\left|R_o\left(t\right)\right|}\right)\\ -\arctan \left(\frac{v_y\left(t\right)}{v_z\left(t\right)}\right)\end{array}\right]$

Yaw in the following formula (t), roll (t) and pitch (t) represent the corresponding relation of time t and crab angle, roll angle and the angle of pitch in the attitude angle of satellite definite object point respectively.

2. the targeted attitude angle of each moment point satellite that obtains according to attitude of satellite maneuvering range and step 1 is calculated the visible time interval [t of satellite to each summit of band ₁, t ₂] _k, k=1,2,3,4.

Satellite is subject to the attitude maneuver ability of satellite to the observation of target, so has only in the attitude maneuver scope of the targeted attitude of satellite at satellite, could carry out observation mission.For k summit,

T representes the time range that limits, if corresponding attitude angle [yaw roll pitch] satisfies | and roll|≤roll _Max, | pitch|≤pitch _Max, roll wherein _Max, pitch _MaxThe maximum roll angle of expression satellite and the maximum angle of pitch, then t ∈ [t ₁, t ₂] _k, i.e. [t ₁, t ₂] _kFor the set of the t that satisfies above-mentioned condition, if [t ₁, t ₂] _kNot existing, is " not having visible time window " with this target label.Calculation process is as shown in Figure 2.

3. according to the visible time interval [t of satellite to each summit of band ₁, t ₂] _k, k=1,2,3,4, calculate satellite to the visible time interval of band [t ' ₀, t ' _n].

To the visible time interval [t of satellite to each summit ₁, t ₂] _k, k=1,2,3,4 seek common ground, promptly obtain satellite to the visible time interval of band [t ' ₀, t ' _n].

4. according to ground sun altitude result of calculation, reject time interval in the shadow zone, ground.

Between the visible range that generally step 3 calculates [t ' ₀, t ' _n] have a plurality of separating, wherein between the part visible range in the shadow zone, ground, can't satisfy the image-forming condition of optical camera, should give rejecting.

Between the visible range that step 3 is obtained [t ' ₀, t ' _n], a bit calculate the sun altitude ε of this moment point observed object from wherein optional, if ε＜0, then this is rejected in the shadow zone, ground, otherwise keeps.If do not exist [t ' ₀, t ' _n] not in the shadow zone, ground, then with this target label be " time window is in the shadow zone, ground ".

Sun altitude is relevant with the time, and computation process is following:

(1) calculates Julian date and Julian century number according to the Gregorian calendar time (Pascal Greggory is gone through)

Be respectively Y, M, D if provide year, the moon, the day (containing the purpose fraction part) of Gregorian calendar time, then corresponding Julian date is:

$\mathrm{JD}=D-32075+[1461\×(Y+4800+[\frac{M-14}{12}\left]\right)\÷4]$

$+[367\×(M-2-[\frac{M-14}{12}]\×12)\÷12]$

$-[3\×[(Y+4900+[\frac{M-14}{12}\left]\right)\÷100]\÷4]-0.5$

The integral part that X is got in [X] expression in the formula, fraction part is omitted.

The yojan Julian date of starting at from 12 o'clock on the 1st January of nineteen fifty is MJD=JD-2433283

Revising the Julian century number is MJC=MJD/36525

(2) calculate the variation of the sun with respect to the orbit parameter of the earth

Major semi-axis a _h=1.49597927 * 10 ⁸

Eccentric ratio e _h=1.67301085 * 10 ^-2-4.1926 * 10 ^-5MJC-1.26 * 10 ^-7MJC ²

Orbit inclination (being ecliptic obliquity)

i _h＝23.4457888616-1.30141669×10 ^-2MJC-9.445×10 ^-7MJC ²+5.000×10 ^-7MJC ³；

Argument of perigee ω _h=1.67301085 * 10 ^-2-4.1926 * 10 ^-5MJC-1.26 * 10 ^-7MJC ²

Mean anomaly

M _h＝358.000682-0.9856002623MJD-1.550000×10 ^-4MJC ²-3.3333×10 ^-6MJC ³；

Right ascension of ascending node Ω _h=0;

(3) adopt solution by iterative method equation E _h-e _hSinE _h=M _h, obtain eccentric anomaly E _h, iterative formula is E _{H (k+1)}=e _hSinE _{H (k)}+ M _hOr

Initial value E _{H (0)}=M _h

(4) by E _hAnd e _hThe anomaly of looking for the truth θ _h

$\mathrm{tg}\frac{{\mathrm{\&theta;}}_{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">h</figure-callout>}}}{2}=\sqrt{\frac{1-{\mathrm{<figure-callout\; id="1"\; label="e\; h"\; filenames="HSA00000498678500021.png,HSA00000498678500033.png"\; state="\{\{state\}\}">e</figure-callout>}}_h}{1+e_h}}\mathrm{<figure-callout\; id="2"\; label="tg\; E\; h"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">tg</figure-callout>}\frac{E_h}{}\frac{{}_{}}{2};$

(5) according to formula u _h=ω _h+ θ _hCalculate latitude argument (being ecliptic longitude);

(6) according to formula tg α _h=cosi _hTgu _hCalculate sun right ascension α _h

(7) according to formula sin δ _h=sini _hSinu _hCalculate solar declination;

(8) according to formula α _G=α _G0+ 6.3003881t calculates the Greenwich right ascension;

(9) α _G0And α _GWith radian (rad) is unit, and the time of t for starting at from this year initial (by universal time) constantly is unit with the mean solar day.α _G0Value is from find the astronomical chronicle then;

(10) Calculation of ground targets solar elevation angle λ,

is the observed target latitude and longitude.

The derivation of said method sees " spacecraft flight principle of dynamics " (Xiao Yelun writes, nineteen ninety-five) that the Yuhang Publishing House publishes for details.

But four, calculate satellite and the call duration time interval of specifying land station

This part calculating can be accomplished through business softwares such as STK, and concrete steps are geographical longitudes and latitudes of input Coordinated Universal Time(UTC) UTC time t, satellite orbit parameter and land station in STK

The antenna of setting land station then receives elevation angle EA, but can obtain the interval [t of call duration time of satellite and land station _Gs1, t _Gs2].

Five, calculate satellite and can carry out the real time interval that passes task

The satellite that obtains according to third part is to the visible time window [t of target ₀', t _n'] but and the interval [t of the 4th part satellite that obtains and the call duration time of specifying land station _Gs1, t _Gs2], calculate satellite and can be carried out to picture and the time interval [t that passes down simultaneously task ₀, t _n], concrete steps are following:

(1) if t ₀'＜t _Gs1＜t _Gs2＜t _n', t then ₀=t _Gs1, t _n=t _Gs2

(2) if t _Gs1＜t ₀'＜t _n'＜t _Gs2, t then ₀=t ₀', t _n=t _n';

(3) if t _Gs1＜t ₀'＜t _Gs2＜t _n', t then ₀=t ₀', t _n=t _Gs2

(4) if t ₀'＜t _Gs1＜t _n'＜t _Gs2, t then ₀=t _Gs1, t _n=t _n';

(5) if t ₀'＜t _n'＜t _Gs1＜t _Gs2, [t then ₀, t _n] do not exist, promptly do not exist to be carried out to picture and the time interval that passes down simultaneously, be " do not exist and can pass the interval in fact " with task flagging.

Six, the structure imaging quality is confirmed function

Image quality is mainly swept and parameter determining such as the geometric resolution of linear array both direction, modulation transfer function MTF, signal to noise ratio (S/N ratio), fabric width by pushing away.Wherein MTF is main relevant with static factor such as camera design manufacturing and satellite attitude stabilization degree, flutter etc., and therefore the selection for observation time point does not have actual influence, is normal value when the setting of camera imaging parameter remains unchanged.Mainly by terrain object reflectivity and sun altitude decision, for the appointed area, reflectivity is certain to signal to noise ratio (S/N ratio), and sun altitude is big more, and signal to noise ratio (S/N ratio) is high more; Under the prerequisite that camera design parameter and satellite orbital altitude are confirmed; Fabric width is relevant with the angle of pitch with the observation roll angle, and the roll angle and the angle of pitch are big more, and fabric width is big more; Because there is contradiction in big fabric width with high resolving power, so fabric width is not as the leading indicator of image quality calculating.Push away and sweep resolution and influenced by the angle of pitch, the angle of pitch is big more, pushes away that to sweep resolution poor more.Linear array resolution is influenced by roll angle mainly, and roll angle is big more, and linear array resolution is poor more.Therefore the dynamic factor that influences image quality mainly comprises roll angle, the angle of pitch and sun altitude.According to the content of third part, under the prerequisite that satellite, target are confirmed, observation time is unique determinative of roll angle, the angle of pitch and sun altitude, so image quality can be expressed as the function of a single variable of time.

Among the present invention, the image quality Comprehensive Assessment by MTF, push away geometric resolution, signal to noise ratio (S/N ratio) (snr) and fabric width (breath) weighted sum of sweeping direction (GSDx) and linear array direction (GSDy) and obtain.At first calculate each item index respectively, then the result of calculation of each item index is converted into the image quality of single index, again with each item index according to image-forming condition.Weighting obtains the Comprehensive Assessment result.Computation process is following:

1. computational geometry resolution

Known satellite orbit altitude H, attitude angle [yaw roll pitch], camera pixel dimension d, focal distance f, field angle FOV, earth radius Re, satellite pushes away sweeps geometry of direction resolution GSD _xWith linear array geometry of direction resolution GSD _yFor

${\mathrm{GSD}}_x=H\&CenterDot;\sec \mathrm{\&beta;}\&CenterDot;\frac{\mathrm{<figure-callout\; id="2"\; label="d\; f\; sec"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">d</figure-callout>}}{f}{\sec }^{}{}^2\mathrm{\&gamma;}$

${\mathrm{GSD}}_y=H\&CenterDot;\mathrm{se}{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">c</figure-callout>}}^2\mathrm{\&beta;}\&CenterDot;\frac{d}{f}\sec \mathrm{\&gamma;}$

Wherein

expression with the camera shooting spot projection to pushing away the equivalent side-sway angle and the equivalent angle of pitch of sweeping after direction and the linear array direction.

2. it is wide to be calculated to be film size

The fabric width computing method are as shown in Figure 3, and O representes the earth centre of sphere among the figure, and S representes satellite; S ' expression substar ,+X representes the working direction of satellite, promptly camera pushes away and sweeps direction; + Y representes camera linear array direction, supposes that the earth is desirable spheroid, and XY crosses on the plane substar and earth sphere is tangent.The intersection points on A, B 2 expressions viewing field of camera corner edge and XY plane, A ', B ' expression viewing field of camera corner edge and earth surface intersection point, then the spherical distance of A ', B ' point-to-point transmission is the fabric width of the attitude of satellite after motor-driven.The F point is the intersection point on camera optical axis and XY plane, and F ' is the intersection point of camera optical axis and earth surface.

It is α that note satellite optical axis points to the angle, and the attitude maneuver that A, B are ordered points to the angle and is respectively α ₁, α ₂, the character according to right-angle triangle has

$\mathrm{\&alpha;}=\arctan \left(\frac{\sqrt{{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{roll}+{\tan }^2\mathrm{pitch}}}{\cos \mathrm{roll}}\right)$

${\mathrm{\&alpha;}}_1=\arctan \left(\frac{\sqrt{{\sin }^2(\mathrm{roll}-\frac{\mathrm{FOV}}{2})+{\tan }^2\mathrm{pitch}}}{\cos (\mathrm{rpll}-\frac{\mathrm{FOV}}{2})}\right)$

${\mathrm{\&alpha;}}_2=\arctan \left(\frac{\sqrt{{\sin }^2(\mathrm{roll}+\frac{\mathrm{FOV}}{2})+{\tan }^2\mathrm{pitch}}}{\cos (\mathrm{rpll}+\frac{\mathrm{FOV}}{2})}\right)$

According to the triangulo operation relation, in triangle SOF ', can obtain:

So have

${\mathrm{SF}}^{\&prime;}=(R_e+H)\cos \mathrm{\&alpha;}-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&alpha;}}$

In like manner can get

${\mathrm{SA}}^{\&prime;}=(R_e+H)\cos {\mathrm{\&alpha;}}_1-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2{\mathrm{\&alpha;}}_1}$

${\mathrm{SB}}^{\&prime;}=(R_e+H)\cos {\mathrm{\&alpha;}}_2-\sqrt{{R_e}^2-{(R_e+H)}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="HSA00000498678500033.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2{\mathrm{\&alpha;}}_2}$

Can know ∠ A ' SB '=∠ ASB=FOV by Fig. 3, calculate the length of line segment A ' B ' in the middle employing cosine law of triangle A ' SB ':

$A^{\&prime;}{B}^{\&prime;}=\sqrt{{\mathrm{SA}}^{\&prime;2}+{\mathrm{SB}}^{\&prime;2}-{2\mathrm{SA}}^{\&prime;}\&CenterDot;{\mathrm{SB}}^{\&prime;}\&CenterDot;\cos \mathrm{FOV}}$

By the corresponding geocentric angle of the length computation of line segment A ' B '

$\mathrm{\&phi;}=2\arcsin \left(\frac{A^{\&prime;}{B}^{\&prime;}}{{2R}_e}\right)$

Fabric width is the spherical distance L of A ', B ' point-to-point transmission _{A ' B '}=φ R _e

3. calculating signal to noise ratio (S/N ratio)

After CCD camera TDI integration progression was selected, signal to noise ratio (S/N ratio) was by sun altitude and the decision of earth surface reflection rate.Snr computation adopts signal to noise ratio (S/N ratio) numerical table under the structure different condition, and table of logarithm carries out the method for bivariate interpolation again.The structure of signal to noise ratio (S/N ratio) numerical table adopts 6S (Second Simulation of the Satellite Signal in the Solar Spectrum) computed in software to obtain, and " analysis of HJ-1A Satellite CCD Camera incident light spectrum radiance " that Sun Jifu, Wu Yanlin deliver on 2003 the 24th the 2nd phases of volume " space flight is returned and remote sensing " has more specific introduction to this method.Through 6S software; Obtaining sun altitude is 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, 90 °; The earth surface reflection rate is 7%, 10%, 15%, 20%, 26%, 40%, 50%, 60%, 70%, 80%, 90%, 100% o'clock corresponding respectively signal to noise ratio (S/N ratio); Adopt the binary function interpolation calculation to obtain any sun altitude and the corresponding signal to noise ratio (S/N ratio) of any face of land reflectivity on this basis; The binary function interpolation has detailed explanation in " numerical analysis " (Yan Qingjin writes, 2000) book that publishing house of BJ University of Aeronautics & Astronautics publishes, method is following:

Known signal to noise ratio (S/N ratio) numerical table snr (r _i, ε _j), i=0,1 ..., 11, r _i=0.07,0.15 ..., 1.00, expression earth surface reflection rate, j=0,1 ..., 8, ε _j=10,20 ..., 90, the expression sun altitude.If any face of land reflectivity and sun altitude (r, ε) satisfy:

r _i-1≤r＜r _i，ε _j-1≤ε＜ε _j

Then corresponding snr computation formula is:

$\mathrm{snr}(r,\mathrm{\&epsiv;})=\frac{(r-r_i)(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_j)}{(r_{i-1}-r_i)({\mathrm{\&epsiv;}}_{j-1}-{\mathrm{\&epsiv;}}_j)}\mathrm{snr}(r_{i-1},{\mathrm{\&epsiv;}}_{j-1})+\frac{(r-r_i)(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_{j-1})}{(r_{i-1}-r_i)({\mathrm{\&epsiv;}}_j-{\mathrm{\&epsiv;}}_{j-1})}\mathrm{snr}(r_{i-1},{\mathrm{\&epsiv;}}_j)$

$+\frac{(r-r_{i-1})(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_j)}{(r_i-r_{i-1})({\mathrm{\&epsiv;}}_{j-1}-{\mathrm{\&epsiv;}}_j)}\mathrm{snr}(r_i,{\mathrm{\&epsiv;}}_{j-1})+\frac{(r-r_{i-1})(\mathrm{\&epsiv;}-{\mathrm{\&epsiv;}}_{j-1})}{(r_i-r_{i-1})({\mathrm{\&epsiv;}}_j-{\mathrm{\&epsiv;}}_{j-1})}\mathrm{snr}(r_i,{\mathrm{\&epsiv;}}_j)$

The earth surface reflection rate is determined by morphologic characteristics in the above-mentioned algorithm, and for specific objective, the earth surface reflection rate is normal value.

4. calculate each item index individual event quality grade

Calculate the individual event quality grade according to each item index, wherein MTF, geometric resolution and fabric width adopt the method for linear interpolation to calculate, and signal to noise ratio (S/N ratio) is a reference calculation with standard image-forming condition (70 ° of sun altitudes, earth surface reflection rate 26%, 85 minute).

$R_{\mathrm{MTF}}=\frac{\mathrm{MTF}-{\mathrm{MTF}}_{\mathrm{worst}}}{{\mathrm{MTF}}_{\mathrm{best}}-{\mathrm{MTF}}_{\mathrm{worst}}}\&CenterDot;100$

Wherein, MTF _Worst, MTF _BestExpression minimum respectively, maximum MTF.

$R_{\mathrm{GSD}}=\frac{\mathrm{GSD}-{\mathrm{GSD}}_{\mathrm{worst}}}{{\mathrm{GSD}}_{\mathrm{best}}-{\mathrm{GSD}}_{\mathrm{worst}}}\&CenterDot;100$

GSD _Worst, GSD _BestRepresent the poorest, best resolution respectively.

$R_{\mathrm{breath}}=\frac{L-L_{\mathrm{worst}}}{L_{\mathrm{best}}-L_{\mathrm{worst}}}\&CenterDot;100$

L _Worst, L _BestExpression minimum respectively, maximum fabric width.

$R_{\mathrm{snr}}=\left\{\begin{array}{cc}85+\frac{\mathrm{snr}(r,\mathrm{\&epsiv;})-\mathrm{snr}\left(\mathrm{0.26,70}\right)}{\mathrm{snr}\left(\mathrm{1.00,90}\right)-\mathrm{snr}\left(\mathrm{0.07,10}\right)}\&CenterDot;15,& \mathrm{snr}(r,\mathrm{\&epsiv;})>85\\ \frac{\mathrm{snr}(r,\mathrm{\&epsiv;})-\mathrm{snr}\left(\mathrm{0.07,10}\right)}{\mathrm{snr}\left(\mathrm{1.00,90}\right)-\mathrm{snr}\left(\mathrm{0.07,10}\right)}\&CenterDot;15,& \mathrm{snr}(r,\mathrm{\&epsiv;})\&le;85\end{array}\right.$

5. calculate the image quality integrated level

Image quality grade R=R (t) expression formula is following:

R (t)=∑ η _iR _i(t)=η _MTFR _MTF+ η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _SnrR _Snr(t)+η _BreathR _Breath(t) η _MTF, η _GSDx, η _GSDy, η _SnrAnd η _BreathThe weight of representing single index respectively, the weight of single index satisfies ∑ η=1.Different based on user's request, the weight of each item index can be adjusted.Comprehensive grading is the weighted sum of each item index mark.Except that MTF was normal value, other index scoring was the function of time.

Seven, the existence of judgement time window

The function of a single variable expression formula R=R (t) that adopts the 6th part to obtain calculates respectively what step 5 was confirmed can pass time interval [t in fact ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m).Remember that minimum permission image quality is R _p, with R _pWith R ₀, R _n, R _MaxCompare, image quality requires can pass interval [t in fact for satisfying of setting the tasks ₁, t ₂] whether exist.

During the optical satellite imaging, adopt the substar image quality best usually, so R _MaxApproximate the high imaging quality grade of this visible time interval, at [t ₀, t _m] interval, R=R (t) can be approximately monotonically increasing function, at [t _m, t _n] interval, R=R (t) can be approximately monotonic decreasing function.

(1) if R _Max＜R _p, can know by the monotonicity of function, then time interval [t ₁, t ₂] do not exist, task flagging is " not satisfying image quality requires ";

(2) if R _Max＞R _p, R ₀>=R _p, R _n>=R _p, can know that by the monotonicity of function visible time interval satisfies image quality requirement, t fully ₁=t ₀, t ₂=t _n

(3) if R _Max＞R _p, R ₀＜R _p, R _n>=R _p, can know t by the monotonicity of continuous function intermediate value theorem and function ₁∈ (t ₀, t _m), t ₂=t _n, adopt the flat-sawn method to ask t ₁

(4) if R _Max＞R _p, R ₀>=R _p, R _n＜R _p, can know t by the monotonicity of continuous function intermediate value theorem and function ₁=t ₀, t ₂∈ (t _m, t _n), adopt the flat-sawn method to ask t ₂

(5) if R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), adopt the flat-sawn method to ask t ₁, t ₂

Eight, adopt flat-sawn method cutting time window

According to minimum permission image quality R _p, can pass interval [t in fact what satisfy that image quality requires ₁, t ₂] the interior flat-sawn method solving equation R that adopts _p=R (t _p), obtain the time window starting point t in the 7th part steps (3), (5) ₁, the time window end point t in step (4), (5) ₂

Flat-sawn method (also claiming secant method) is to find the solution complex nonlinear equation a kind of numerical solution commonly used, and its advantage is that speed of convergence is very fast, and the rank of speed of convergence are at least 1.618, and has avoided Newton method to need the deficiency of computing function derivative.

Flat-sawn method solving equation R _p=R (t _p) step following:

As [R (t ₀)-R (t _p)] [R (t _m)-R (t _p)]＜0 o'clock,

And satisfy R _p=R (t _p).Make x _-1=t ₀, x ₀=t _m, for k=0,1 ..., M carries out

(1) calculates $x_{k+1}=x_k-\frac{R\left(x_k\right)\&CenterDot;(x_k-x_{k-1})}{R\left(x_k\right)-R\left(x_{k-1}\right)};$

(2) if | x _K+1-x _k|＜σ, get t _p≈ x _K+1, obtain the time window starting point, otherwise change (1).Wherein M representes maximum iteration time, and σ is the error of calculation of permission.

Make x _-1=t _m, x ₀=t _n, can obtain R with method _p=R (t _p) at interval (t _m, t _n) on another root, i.e. time window end point.

Nine, calculate the observation duration of target

The observation duration of band, promptly, depend on the length of band from beginning to observe the duration of end observation.To a multi-ribbon task,, can obtain the observation duration of all bands because therefore the equal in length of all bands only needs an optional band to calculate.To each band; The satellite that at first obtains according to the step 1 of third part points to the attitude angle on each summit; Adopt the flat-sawn method to calculate the beginning observation time and end observation time of band again, obtain the observation duration of band, judge at last whether the visible time window of band can comprise the observation duration of band; If can not, then this task can not be carried out.Be that example describes with a band below:

1. each the moment point satellite that obtains according to the step 1 of third part points to the attitude angle on each summit of band, [the t that obtains in the step 2 of third part ₁, t ₂] _k, k=1, in 2,3,4, adopting the flat-sawn method to calculate the angle of pitch is 0 o'clock, satellite points to the time on each summit of band.

Be example with summit k below, explain and adopt flat-sawn method solving equation Pitch (t _PkThe step of)=0:

Satellite is to the attitude maneuver ability decision by satellite of visible time of target, and satellite is changed to 0 to the observation angle of pitch of fixed target by positive maximal value in the rail motion process, become negative maximal value by 0 again, also the i.e. visible time interval [t of k on the summit ₁, t ₂] _kOn, satellite is at first t ₁The angle of pitch be roll _Max, 1 t in the end ₂The angle of pitch be-roll _Max, therefore interval [t ₁, t ₂] _kIn the satellite angle of pitch must be arranged is 0 moment point, promptly as Pitch (t ₁) Pitch (t ₂)＜0 o'clock,

And satisfy Pitch (t _Pk)=0.

Make x _-1=t ₁, x ₀=t _Pk, for i=0,1 ..., M carries out

(1) calculates $x_{i+1}=x_i-\frac{\mathrm{Pitch}\left(x_i\right)\&CenterDot;(x_i-x_{i-1})}{\mathrm{Pitch}\left(x_i\right)-\mathrm{Pitch}\left(x_{i-1}\right)};$

(2) if | x _I+1-x _i|＜σ, get t _Pk≈ x _I+1, obtaining the angle of pitch is 0 o'clock, the time on satellite definite object summit, otherwise change (1).

Wherein M representes maximum iteration time, and σ is the error of calculation of permission.

2. because satellite must start from certain summit to the observation of band, also end at certain summit, therefore according to the visible time of satellite to each summit, can confirm satellite to the beginning observation time of band with finish observation time.

With t _PkAccording to the sequencing ordering, the note time the earliest is T _Start, the time the latest is T _End, represent the beginning observation time of band respectively and finish observation time.

3. according to the lasting observation time of computes band

T _last＝T _end-T _start

T _LastBe that visible time interval according to each summit of band calculates, consider the influence of ground shadow, therefore also need judge and reject behind the time interval in shadow zone, ground, satisfy the interval [t that image quality requires and can pass in fact what the 8th part obtained ₁, t ₂] whether can accomplish observation to band:

If T _Last＞t ₂-t ₁, it is shorter than the observation duration that this band satisfies the visible time window of all requirements, and whole observation mission can't be accomplished.

Ten, export the time window information of all targets, for being labeled of task, the reason that output can not be accomplished is submitted to the mission planning system with not being labeled of task, carries out mission planning and scheduling.

Embodiment

Consider a motor-driven imaging satellite of rapid posture that runs on the sun synchronization circular orbit; Epoch, 00:00:00.000 on July 26th, 2009 (universal time coordinated UTC) wink radical was semi-major axis 7051.2km constantly; 97.3087 ° of orbit inclinations, 249.784 ° of right ascension of ascending node, 0 ° of latitude argument.Earth surface reflection rate 50%.Attitude of satellite maneuvering range is pitch orientation and rotating direction ± 45 °.Under to pass bit rate be 800Mbps.The geographical latitude and longitude information of target is as shown in table 1, and all observed objects in this example are point target.

The geographical longitude and latitude of table 1 target

Task number	Geographic longitude (°)	Geographic latitude (°)	Minimum permission image quality R p
				1	61.1834	37.5404	70
2	130.9340	59.6211	70
				3	114.5653	-3.1025	70
4	121.5680	44.2996	70
				5	122.6877	41.2745	70
6	96.2793	36.6533	70

The geographical latitude and longitude information of available land station is as shown in table 2, and antenna receives elevation angle EA and is 10 °.

Table 2 can be used the geographical longitude and latitude of land station

Land station's title	Geographic longitude (°)	Geographic latitude (°)
			Beijing	116.388	39.9062
Kunming	102.7021	25.051

The satellite optical camera adopts panchromatic and multispectral two kinds of CCD, panchromatic pixel dimension 10 μ m, and multispectral pixel dimension 40 μ m, camera focus 10m, 1.07 ° of field angle, MTF is 0.0902 to the maximum, and minimum 0.0818.Panchromatic CCD TDI integration progression is set at 24 o'clock, and MTF is 0.0895.The signal to noise ratio (S/N ratio) numerical table is following:

Adopt the inventive method following to the pre-treatment step of these real biography tasks:

(1) the mission area band is divided

Because all observed objects in this example are point target, therefore need not carry out band and divide.

(2) the visible time window of calculation task

According to orbit elements of satellite; Calculate orbital position, the speed of satellite under the J2000 coordinate system in the universal time coordinated UTC 00:00:00.000 on July 27,2009 00:00:00.000 to 2009 year on the 26th July in, calculate the observation angle of each whole second moment satellite then task.According to attitude of satellite maneuvering range, obtain its visibility window of satellite and task.The observation angle of task 1 has exceeded the maximum attitude maneuver scope of satellite, so task 1 is marked as " do not have visible time window ", and the result of calculation of other tasks is as shown in table 3.

The visible time window of table 3 task

Task number	It is thus clear that the zero hour t ' 0	It is thus clear that the finish time t ' n
			2	00:30:55	00:34:25
3	00:48:11	00:51:32
			4	00:35:22	00:38:44
5	00:36:04	00:39:32
			6	02:15:31	02:18:58

Except task 1 " did not have visible time window ", all the other tasks all were in sun according to the district.

(3) but calculate the call duration time of land station and satellite

According to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn].Generally, but there are a plurality of communication intervals in each land station and satellite, and result of calculation is as shown in table 4.

But the call duration time of table 4 target and satellite

(4) calculation task can pass time interval in fact

According to step (3) but the satellite that obtains and the communication interval [t of land station _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, confirm that satellite can carry out the real time interval [t that passes to each task ₀, t _n], result of calculation is as shown in table 5.

Table 5 target can pass the interval in fact

Task 2～task 6 all exists can pass the interval in fact, and task 4～task 6 and two land stations all exist and can pass the interval in fact.

(5) confirm the major influence factors of image quality

Because the selection of MTF and observation time point is irrelevant, not the principal element that influences image quality therefore;

Can pass between the time window 00:31:37 to 00:34:25 in fact in task 2; The angle of pitch and roll angle result of calculation such as Fig. 4, shown in Figure 5; Angle of pitch variation range is 31.7 °～-45 °; The roll angle variation range is 0.4 °～3.4 °, so angle of pitch variation is the principal element that influences image quality.Signal to noise ratio (S/N ratio) is determined that by sun altitude sun altitude result of calculation is as shown in Figure 6, and in whole its visibility window, the variation range of sun altitude is no more than 1 °, is not the principal element that influences image quality therefore.

The analysis result of task 3～task 6 is identical with task 2.

(6) calculate image quality

Because observation attitude angle and sun altitude all can be expressed as the function of a single variable of time, so image quality also can be expressed as the function of a single variable R (t) of time.

Because there are contradiction in big fabric width and high resolving power, when guaranteeing high resolving power, fabric width is reduced through the restriction attitude angle.Usually image quality confirm method with high resolving power as a prior index.In the present embodiment weight of fabric width in image quality is made as 0, promptly do not consider.

The weight allocation of each item index is following:

Index	Weight
		MTF	0.125
Signal to noise ratio (S/N ratio)	0.375
		Panchromatic pushing away swept directional resolution	0.125
Panchromatic linear array directional resolution	0.125
		Multispectral pushing away swept directional resolution	0.125
The multi-spectral linear array directional resolution	0.125
		The imaging fabric width	0

Promptly

R (t)=0.125R _MTF+ 0.125R _{Panchromatic GSDx}(t)+0.125R _{Panchromatic GSDy}(t)+0.125R _{Multispectral GSDx}(t)+0.125R _{Multispectral GSDy}(t)+0.375R _Snr(t)

Because the task One's name is legion, only the result of calculation with task 2 is the representative explanation.Fig. 7 can pass the change curve of the scoring of image quality in the time window with observation time in fact for task 2.

(7) judgement time window [t ₁, t ₂] existence

Because the task One's name is legion, only the computation process with task 2 is the representative explanation.

To task 2, with t ₀=2009-7-2600:00:00 is the reference time, by t ₀=1897 seconds (is t ₀=2009-07-2600:31:37), t _n=2065 seconds (is t _n=2009-7-2600:34:25), the highest moment point t of image quality _m=1959, obtain R (t ₀)=64.34, R (t _m)=90.88, R (t _n)=56.28.

Because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by the continuous function intermediate value theorem, the t of task 2 ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₁, t ₂

The result of calculation of other tasks is following:

Task 3:

R (t ₀)=56.23, R (t _m)=57.98, R (t _n)=57.98 are because R _Max＜R _p, can know time interval [t by the monotonicity of function ₁, t ₂] do not exist, task 3 is labeled as " not satisfying image quality requires ";

Task 4:

But communication interval: R (t with Beijing Station ₀)=55.38, R (t _m)=88.20, R (t _n)=55.95 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₁, t ₂

But communication interval: R (t with Station in Kunming ₀)=87.93, R (t _m)=87.93, R (t _n)=55.95 are because R _Max＞R _p, R ₀>=R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁=t ₀, t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₂

Task 5:

But communication interval: R (t with Beijing Station ₀)=56.60, R (t _m)=91.26, R (t _n)=56.78 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₁, t ₂

But communication interval: R (t with Station in Kunming ₀)=80.29, R (t _m)=91.26, R (t _n)=56.78 are because R _Max＞R _p, R ₀>=R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁=t ₀, t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₂

Task 6:

But it is identical: R (t with the communication interval of Beijing Station and Station in Kunming ₀)=56.33, R (t _m)=91.18, R (t _n)=56.82 are because R _Max＞R _p, R ₀＜R _p, R _n＜R _p, by continuous function intermediate value theorem, t ₁∈ (t ₀, t _m), t ₂∈ (t _m, t _n), need to adopt the flat-sawn method to ask t ₁, t ₂

(8) adopt the flat-sawn method to reduce time window [t ₁, t ₂]

For passing the interval task of not satisfying the image quality requirement that exists in fact, adopt the flat-sawn method to calculate t respectively ₁, t ₂, result of calculation is as shown in table 6.

What table 6 satisfied image quality can pass the interval in fact

(9) confirm the observation duration

Because all tasks are point target in the example, observation duration less than 1 second all can pass time interval less than what satisfy image quality in fact, does not therefore have the task of " do not satisfy and observe the duration ".

(10) pre-service result (as shown in table 7) is exported to the mission planning system, carry out mission planning and scheduling.

The pre-service result of table 7 task

The content of not doing to describe in detail in the instructions of the present invention belongs to those skilled in the art's known technology.

Claims (1)

1. preprocess method to real biography task is characterized in that step is following:

(1) according to the camera fabric width mission area band is divided;

(2) confirm the visible time interval [t of satellite according to the maximum angle of pitch of satellite and maximum roll angle and task stripe information to each band ₀', t _n'], reject visible time window of nothing and time window task in the shadow zone, ground; Visible time interval [the t of each band ₀', t _n'] by the visible time interval [t of satellite to these four summits of band ₁, t ₂] _k, k=1,2,3,4 seek common ground and reject behind the time interval in shadow zone, ground obtains; Satellite is confirmed by the maximum angle of pitch and the maximum roll angle of satellite the visible time interval on the single summit of band;

(3) according to ground station location and satellite orbit parameter, but the interval [t of the call duration time of calculating land station and satellite _D0, t _Dn];

(4) according to step (3) but the interval [t of the call duration time that obtains _D0, t _Dn] to visible time interval [t ' ₀, t ' _n] reduce, confirm that satellite can carry out the real time interval [t that passes to task ₀, t _n], rejecting does not exist can pass interval task in fact;

(5) with modulation transfer function MTF, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction be as the principal element that influences picture quality, can pass interval [t in fact what step (4) was confirmed ₀, t _n] in picture quality is expressed as the function of a single variable R (t) of time,

R(t)＝η _MTFR _MTF+η _GSDxR _GSDx(t)+η _GSDyR _GSDy(t)+η _snrR _snr(t)+η _breathR _breath(t)，

η in the formula _MTF+ η _GSDx+ η _GSDy+ η _Snr+ η _Breath=1, R _MTF, R _GSDx(t), R _GSDy(t), R _{Snr (}T), R _Breath(t) be respectively modulation transfer function MTF, the geometric resolution, signal to noise ratio (S/N ratio) and the fabric width that push away the geometric resolution of sweeping direction, linear array direction and the function of a single variable of time relation;

(6) the function of a single variable expression formula that adopts step (5) to obtain calculate respectively in step (4), confirm can pass time interval [t in fact ₀, t _n] two end points t ₀And t _nAnd the highest moment point t of interval image quality _mPicture quality R ₀=R (t ₀), R _n=R (t _n), R _Max=R (t _m);

(7) the minimum permission image quality of note is R _p, with R _pThe R that obtains with step (6) ₀, R _n, R _MaxCompare, set the tasks satisfy that image quality requires can pass interval [t in fact ₁, t ₂], reject and do not satisfy the task that image quality requires;

(8) adopt the flat-sawn method to calculate the observation duration T of each task band _Last, T _LastBegin to finish time of being continued to the summit of the last observation of this band for the summit of observing at first from this band; Observation duration T when the task band _LastDuring less than the task observation window time interval length of step (7), this task be for executing the task, and all can be executed the task submit to the mission planning system and carry out mission planning and scheduling.

Images