CN107515396B - A kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design - Google Patents
A kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design Download PDFInfo
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- CN107515396B CN107515396B CN201710532862.2A CN201710532862A CN107515396B CN 107515396 B CN107515396 B CN 107515396B CN 201710532862 A CN201710532862 A CN 201710532862A CN 107515396 B CN107515396 B CN 107515396B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/904—SAR modes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
- G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
- G01S13/904—SAR modes
- G01S13/9064—Inverse SAR [ISAR]
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Abstract
The invention discloses a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, includes the following steps: to calculate object run track and Covering time, setting imaging center moment, computer azimuth angle, the elevation angle, imaging start and stop moment and target oblique distance, setting redundancy oblique distance and initial transmissions pulsewidth, selection PRF, judges DcWhether it is more than the upper limit, calculates echo window length and Dr, judge DrIt whether is more than to deposit biography ability, calculate echo initial time, adjustment beam position, calculate antenna gain and echo signal intensity, setting MGC, be imaged.The present invention fully considers extraterrestrial target kinetic characteristic and radar system limitation to be imaged, in conjunction with STK software, solve the problems, such as that the parameters of target motion in Traditional Space target inverse synthetic aperture radar imaging parameter designing, radar beam are directed toward and system parameter computational accuracy is insufficient.In such a way that mechanical scanning and electric scanning combine, beam position needed for realizing extraterrestrial target inverse synthetic aperture radar imaging reduces cost of implementation and complexity.
Description
Technical field
The present invention relates to a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters designs, pass through the inverse synthesis hole of ground
Radar system parameters when diameter radar carries out high-resolution imaging to extraterrestrial target design, and belong to radar system design technology neck
Domain, the extraterrestrial target include satellite, space station, airship and rocket end etc..
Background technique
Since October 4 nineteen fifty-seven, since the former Soviet Union succeeds in sending up first artificial earth satellite, world's space technology is flourishing
Development, the scope of activities of the mankind is expanded into outer space, greatly extends the visual field of the mankind, expedited the emergence of as satellite navigation,
A series of deep AEROSPACE APPLICATIONs for changing human life style such as communication and broadcast.With the development of space technology, the mankind are to too
The a large amount of spacecraft of air-launched ends 2014, and the whole world has succeeded in sending up nearly 7000 spacecrafts.It is so numerous
Spacecraft also comes to subsequent Spacecraft Launch and human information safety belt potential while providing convenient to human lives
It threatens.In addition, the space junk to gather in space, the spacecraft remains scrapped and ballistic weapon are also next huge to the safety belt of the mankind
Risks.Therefore, it is highly desirable to detect extraterrestrial target, be imaged, identify and catalogue.
Inverse Synthetic Aperture Radar (ISAR) is a kind of high-resolution microwave that non-cooperative moving targets can be imaged
Remote sensing system, it obtains orientation high-resolution, benefit relative to inverse synthetic aperture caused by static radar using moving target
Distance is obtained to high-resolution with broadband signal.ISAR has round-the-clock, round-the-clock, operating distance is remote and imaging resolution is high etc.
Advantage is suitble to be observed extraterrestrial target, can be used to carry out satellite dynamic surveillance, and space junk detection, is led at space cataloguing
Early warning etc. is played, for space situation awareness, ensures that space travel is of great significance safely.
Institutes Of Technology Of Nanjing Cao eastwards in the master thesis of entitled the ISAR technical research of imaging " extraterrestrial target ",
The design of extraterrestrial target inverse synthetic aperture radar imaging system and signal processing are described and are studied, but this article is not directed to
Extraterrestrial target feature provides accurate target track parameter and calculates and radar system parameters design method.University of Electronic Science and Technology's model
Record it is macro in the doctorate of entitled " inverse synthetic aperture radar imaging and perturbation technique study ", to Aerospace Satellite target ISAR at
As principle, simulated radar echo and satellite motion model are analyzed, but the motion model that provides of this article be not able to satisfy it is high-precision
Imaging demand is spent, and does not provide corresponding direction parameter calculating and design method.
Summary of the invention
Technology of the invention solves the problems, such as: overcome the deficiencies in the prior art, the present invention provides a kind of extraterrestrial target is inverse
Synthetic aperture radar image-forming Parameters design, by fully considering that extraterrestrial target kinetic characteristic and radar system to be imaged limit
System, in conjunction with STK software virtual technique, gives a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, solves
Extraterrestrial target kinematic parameter to be imaged, radar beam are directed toward in Traditional Space target inverse synthetic aperture radar imaging parameter designing
With the problem of system parameter computational accuracy deficiency.In such a way that mechanical scanning and radar antenna electric scanning combine, realize
Beam position needed for extraterrestrial target inverse synthetic aperture radar imaging, reduces cost of implementation and complexity.
The technical solution of the invention is as follows:
A kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, includes the following steps:
Step 1: calculating extraterrestrial target running track according to known extraterrestrial target orbit parameter；In satellite simulation tool
Virtual extraterrestrial target to be imaged is established in packet software, and newest orbital data is imported into STK software, updates target track information；
Step 2: a virtual-sensor is arranged for the virtual extraterrestrial target to be imaged that the first step is established, according to ISAR days
Vertical half angle θ is arranged in line maximum scan rangeVHA, vertical half angle θVHACalculation method such as formula (1) shown in:
Wherein ReFor earth radius, H is orbit altitude, θr_maxFor ISAR antenna maximum scan range；
According to ISAR radar present position latitude and longitude coordinates, virtual ground station is established in STK software, it is virtual by analyzing
Virtual-sensor on extraterrestrial target to be imaged is to the coverage condition at virtual ground station, when cover time central instant was top
It carves, i.e. the oblique distance shortest moment；
Step 3: the top moment that crosses for first obtaining second step is set as the imaging center moment, according to real around test site
Border environment, judges whether there is and blocks, and blocks if existing on ISAR radar to the sight of target to be imaged at this time, successively the
The imaging moment for avoiding blocking is found within the scope of the cover time that two steps obtain, and the imaging moment for avoiding blocking is set as being imaged
Central instant；
Step 4: the imaging center moment obtained according to third step is calculated by the visibility analysis tool of STK software
Imaging center moment virtual ground station to the azimuth and the elevation angle of virtual target to be imaged；
Step 5: a new virtual-sensor is established for virtual ground station, in STK software to simulate ISAR radar
System, the vertical half-angle of new virtual-sensor are the half for the antenna beamwidth that expectation target to be imaged passes through direction, newly
Virtual-sensor horizontal half-angle be another dimension of antenna beam angle half；The direction of new virtual-sensor presses the 4th
Walk the azimuth being calculated and elevation angle setting；By analysis virtual ground station sensor to the covering feelings of virtual target to be imaged
Condition, obtain Target Traversing radar beam to be imaged enters moment and departure time, the initial time and knot as this imaging
The beam moment；
Step 6: passing through STK software according to this initial time being imaged and finish time that the 5th step is calculated
Visibility analysis tool calculates the nearest oblique distance R that initial time and finish time ISAR radar is imaged to target to be imagednMost
Remote oblique distance Rf；
Step 7: the farthest oblique distance R being calculated in the 6th stepfWith nearest oblique distance RnIt is oblique that both ends symmetrically increase protective redundancy
Away from Rr, for the ISAR radar return window Design of length and PRF selection in subsequent step；
Step 8: setting ISAR radar initial transmissions pulse is wide according to the limitation of the duty ratio of ISAR radar and data transfer rate
Spend Tp；
Step 9: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith farthest oblique distance
Rf, protective redundancy oblique distance R that the 7th step obtainsr, ISAR radar initial transmissions pulse width T that the 8th step obtainsp, calculate ISAR
The transmitting impulse disturbances band section of radar, shown in calculation method such as formula (2):
Wherein c is the light velocity, and N transmitting receives pulse daley number, and PRT is the transmitting pulse spacing of ISAR radar；
Obtained PRT is taken down by zebra figure in the Interval selecting PRT of radar transmitted pulse interference fringe according to formula (2)
Number obtains ISAR radar PRF；
Step 10: the ISAR radar initial transmissions pulse width T being arranged according to the 8th steppThe ISAR thunder obtained with the 9th step
Up to PRF, ISAR radar duty ratio D is calculatedc, shown in calculation method such as formula (3)
Dc=Tp*PRF (3)
Then judge duty ratio DcWhether exceed the ISAR radar duty ratio upper limit, if exceeding, returns to the 8th step, otherwise,
By ISAR radar initial transmissions pulse width TpIt is determined as actual transmission pulse width, the ISAR radar PRF that the 9th step is obtained
It is determined as practical PRF, and carries out in next step；
Step 11: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith it is farthest tiltedly
Away from Rf, protective redundancy oblique distance R that the 7th step obtainsr, fire pulse width T that the 8th step obtainsp, calculate ISAR radar return window
Length Tw, shown in calculation method such as formula (4):
Step 12: ISAR radar return window length is calculated in the practical PRF and the 11st step that are selected according to the tenth step,
Calculate data transfer rate Dr, shown in calculation method such as formula (5):
Dr=(2*fs*Qn*Tw*BAQ+An*Qn)*PRF (5)
Wherein fsIt is distance to sample frequency, QnQuantization digit, BAQFor data compression rate, AnTo assist data bits；
13rd step, the data transfer rate D being calculated according to the 12nd steprEnergy is stored and transmitted with ISAR radar system data
Power judges data transfer rate DrWhether exceed ISAR radar system data and store and transmit ability, if exceeding, returns to the 7th step, it is no
Then, it carries out in next step；
14th step, the nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarn, the 7th step
Obtained protective redundancy oblique distance RrThe PRF selected with the 9th step calculates ISAR radar return initial time Ts, calculation method such as formula
(6) shown in:
15th step, in such a way that mechanical scanning and ISAR radar antenna electric scanning combine, adjustment imaging needs
Beam position；According to electric scanning angle find antenna wave position so that ISAR radar to the sight of target to be imaged closest to wave beam in
The heart；
16th step, the antenna wave position obtained according to the 15th step, calculate ISAR radar to target to be imaged sight and
The angle of beam center, and then obtain corresponding antenna gain G；
17th step calculates the receiver inlet echo signal intensity I in addition to manual gain control gain value MGCs, meter
Shown in calculation method such as formula (7):
Wherein PtFor peak transmitted power, λ is carrier wavelength, and σ is target state estimator radar cross section, GrcTo increase except manual
Receiving channel overall gain outside beneficial control gain value MGC, the loss of L transmission link, R are ISAR radar being averaged to target oblique distance
Value, can be approximately (Rn-Rf)/2；
The manual gain value MGC of ISAR radar is arranged according to the signal range of receiving of receiver in 18th step,
So that echo-signal is received machine reception；
The echo signal intensity I being calculated according to the 17th steps, calculate the manual gain value of ISAR radar
MGC value range, shown in calculation method such as formula (8):
Wherein IminFor the receivable echo signal intensity of minimum, ImaxFor the corresponding echo signal intensity of the saturation of receiver；
19th step, the ISAR that the practical PRF and actual transmission pulse width, the 14th step that select after the tenth step are obtained
Radar system echo initial time Ts, the obtained ISAR radar manual gain of the obtained antenna wave position of the 15th step, the 18th step
ISAR radar posture is arranged by the scanning mode of the 15th step, by the starting of the imaging obtained in the 5th step in control gain value MGC
Moment and finish time carry out ISAR radar imagery.
In a kind of above-mentioned extraterrestrial target inverse synthetic aperture radar imaging Parameters design, in the first step, track ginseng
The interval of number renewable time and imaging moment is no more than 12 hours.
In a kind of above-mentioned extraterrestrial target inverse synthetic aperture radar imaging Parameters design, in second step, sensor
Type is set as rectangle, and horizontal half-angle is arranged between 0.005 °~0.01 °.
In a kind of above-mentioned extraterrestrial target inverse synthetic aperture radar imaging Parameters design, in the 15th step, pass through
Aerial mechanical, which horizontally rotates, realizes the obtained azimuth of four-step calculation, realizes the by aerial mechanical inclination and antenna electric scanning
The elevation angle that four-step calculation obtains.
It is mechanical in the 15th step in a kind of above-mentioned extraterrestrial target inverse synthetic aperture radar imaging Parameters design
Horizontally rotate Adjustment precision 1 order of magnitude at least smaller than radar beam width.
Compared with the prior art, the invention has the advantages that:
[1] present invention has fully considered the limitation of extraterrestrial target characteristic and ISAR radar system and ISAR imaging to be imaged
Work characteristics gives a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, is extraterrestrial target high-resolution
Imaging provides a kind of economic, efficient implementation.
[2] present invention makes full use of the virtual technology in STK software, passes through the sensing on virtual extraterrestrial target to be imaged
Covering of the device to virtual ground station determines that it's the top moment pasts target；By virtual ground station to the direction of extraterrestrial target to be imaged, really
It is fixed that required azimuth and the elevation angle is imaged；The coverage condition of imaging space target is treated by virtual ground ISAR radar system, really
Surely initial time and finish time is imaged；By the nearest and farthest oblique distance at virtual ground station to extraterrestrial target to be imaged, determine
The parameters such as PRF, ISAR the radar return window length and sampling initial time of ISAR radar system.
[3] present invention increases Observable range, improves systematic error fault-tolerant ability, protect by the way that redundancy oblique distance is rationally arranged
Demonstrate,prove extraterrestrial target echo data complete documentation to be imaged.
[4] present invention is on the basis of guaranteeing that data transfer rate is no more than system capability, by increasing duty ratio and average as far as possible
Transmission power improves system signal noise ratio；By estimating echo signal intensity, the MGC yield value range of needs is calculated, guarantees echo
Signal is properly received.
[5] present invention realizes the beam position of demand in such a way that mechanical scanning and radar antenna electric scanning combine.
Realization demand azimuth is horizontally rotated by aerial mechanical, and the demand elevation angle, drop are realized by aerial mechanical inclination+antenna electric scanning
Low system cost of implementation and complexity.
[6] method that the present invention uses realizes the inverse synthetic aperture of extraterrestrial target using synthetic aperture radar equipment
Radar imagery extends the application range of synthetic aperture radar, enriches the realization rate of inverse synthetic aperture radar imaging.
[7] logic smoothness of the present invention, clear thinking, design rationally, step simplify, those skilled in the art are according to the present invention
The step of tested, can fast and accurately calculate the parameter of inverse synthetic aperture radar imaging, save test period, have
Standby wide market application prospect.
Detailed description of the invention
Fig. 1 is flow chart of the invention
Fig. 2 is PRF selection result figure in embodiment
Fig. 3 is the international space station ISAR figure that embodiment obtains
Specific embodiment
For make technical solution of the present invention more be illustrated, with reference to the accompanying drawing explanation and specific embodiment to the present invention make into
The description of one step:
As shown in Figures 1 to 3, a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, includes the following steps:
Step 1: calculating extraterrestrial target running track according to known extraterrestrial target orbit parameter；In satellite simulation tool
Virtual extraterrestrial target to be imaged is established in packet software, and newest orbital data is imported into STK software, updates target track information；
Step 2: a virtual-sensor is arranged for the virtual extraterrestrial target to be imaged that the first step is established, according to ISAR days
Vertical half angle θ is arranged in line maximum scan rangeVHA, vertical half angle θVHACalculation method such as formula (1) shown in:
Wherein ReFor earth radius, H is orbit altitude, θr_maxFor ISAR antenna maximum scan range；
According to ISAR radar present position latitude and longitude coordinates, virtual ground station is established in STK software, it is virtual by analyzing
Virtual-sensor on extraterrestrial target to be imaged is to the coverage condition at virtual ground station, when cover time central instant was top
It carves, i.e. the oblique distance shortest moment；
Step 3: the top moment that crosses for first obtaining second step is set as the imaging center moment, according to real around test site
Border environment, judges whether there is and blocks, and blocks if existing on ISAR radar to the sight of target to be imaged at this time, successively the
The imaging moment for avoiding blocking is found within the scope of the cover time that two steps obtain, and the imaging moment for avoiding blocking is set as being imaged
Central instant；
Step 4: the imaging center moment obtained according to third step is calculated by the visibility analysis tool of STK software
Imaging center moment virtual ground station to the azimuth and the elevation angle of virtual target to be imaged；
Step 5: a new virtual-sensor is established for virtual ground station, in STK software to simulate ISAR radar
System, the vertical half-angle of new virtual-sensor are the antenna beamwidth that expectation target to be imaged passes through direction (for known quantity)
Half, the horizontal half-angle of new virtual-sensor is the half of the beam angle of another dimension of antenna (for known quantity)；New void
The azimuth and the elevation angle that the direction of quasi- sensor is obtained by four-step calculation are arranged；By analysis virtual ground station sensor to void
The coverage condition for intending target to be imaged, obtain Target Traversing radar beam to be imaged enters moment and departure time, is made with this
Initial time and finish time for this imaging；
Step 6: passing through STK software according to this initial time being imaged and finish time that the 5th step is calculated
Visibility analysis tool calculates the nearest oblique distance R that initial time and finish time ISAR radar is imaged to target to be imagednMost
Remote oblique distance Rf；
Step 7: in order to overcome orbital prediction error, ISAR radar site error and attitude error etc. non-ideal
The influence of factor guarantees target echo data to be imaged by complete documentation, in the farthest oblique distance R that the 6th step is calculatedfMost
Nearly oblique distance RnBoth ends symmetrically increase protective redundancy oblique distance Rr, for the ISAR radar return window Design of length and PRF in subsequent step
Selection；If amount of redundancy is excessive, it is excessively high to will lead to data transfer rate, exceeds ISAR radar limit of power, needs appropriate redundancy, until
It meets the requirements；
Step 8: setting ISAR radar initial transmissions pulse is wide according to the limitation of the duty ratio of ISAR radar and data transfer rate
Spend Tp；Biggish fire pulse width T is selected as far as possiblep, to improve ISAR radar duty ratio, increase average emitted power, improve figure
As signal-to-noise ratio；
Step 9: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith farthest oblique distance
Rf, protective redundancy oblique distance R that the 7th step obtainsr, ISAR radar initial transmissions pulse width T that the 8th step obtainsp, calculate ISAR
The transmitting impulse disturbances band section of radar, shown in calculation method such as formula (2):
Wherein c is the light velocity, and N transmitting receives pulse daley number, and PRT is the transmitting pulse spacing of ISAR radar；
Obtained PRT is taken down by zebra figure in the Interval selecting PRT of radar transmitted pulse interference fringe according to formula (2)
Number obtains ISAR radar PRF；In order to increase ISAR radar average emitted power, reduction azimuth ambiguity should be in system capability range
Biggish PRF is inside selected as far as possible；
Step 10: the ISAR radar initial transmissions pulse width T being arranged according to the 8th steppThe ISAR thunder obtained with the 9th step
Up to PRF, ISAR radar duty ratio D is calculatedc, shown in calculation method such as formula (3)
Dc=Tp*PRF (3)
Then judge duty ratio DcWhether exceed the ISAR radar duty ratio upper limit, if exceeding, returns to the 8th step, otherwise,
By ISAR radar initial transmissions pulse width TpIt is determined as actual transmission pulse width, the ISAR radar PRF that the 9th step is obtained
It is determined as practical PRF, and carries out in next step；
Step 11: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith it is farthest tiltedly
Away from Rf, protective redundancy oblique distance R that the 7th step obtainsr, fire pulse width T that the 8th step obtainsp, calculate ISAR radar return window
Length Tw, shown in calculation method such as formula (4):
Step 12: ISAR radar return window length is calculated in the practical PRF and the 11st step that are selected according to the tenth step,
Calculate data transfer rate Dr, shown in calculation method such as formula (5):
Dr=(2*fs*Qn*Tw*BAQ+An*Qn)*PRF (5)
Wherein fsIt is distance to sample frequency, QnQuantization digit, BAQFor data compression rate, AnTo assist data bits；
13rd step, the data transfer rate D being calculated according to the 12nd steprEnergy is stored and transmitted with ISAR radar system data
Power judges data transfer rate DrWhether exceed ISAR radar system data and store and transmit ability, if exceeding, returns to the 7th step, it is no
Then, it carries out in next step；
14th step, the nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarn, the 7th step
Obtained protective redundancy oblique distance RrThe PRF selected with the 9th step calculates ISAR radar return initial time Ts, calculation method such as formula
(6) shown in:
15th step, in such a way that mechanical scanning and ISAR radar antenna electric scanning combine, adjustment imaging needs
Beam position；According to electric scanning angle find antenna wave position so that ISAR radar to the sight of target to be imaged closest to wave beam in
The heart, it is ensured that link gain maximizes；
16th step, the antenna wave position obtained according to the 15th step, calculate ISAR radar to target to be imaged sight and
The angle of beam center, and then obtain corresponding antenna gain G；
17th step calculates the receiver inlet echo signal intensity I in addition to manual gain control gain value MGCs, meter
Shown in calculation method such as formula (7):
Wherein PtFor peak transmitted power, λ is carrier wavelength, and σ is target state estimator radar cross section, GrcTo increase except manual
Receiving channel overall gain outside beneficial control gain value MGC, the loss of L transmission link, R are ISAR radar being averaged to target oblique distance
Value, can be approximately (Rn-Rf)/2；
The manual gain value MGC of ISAR radar is arranged according to the signal range of receiving of receiver in 18th step,
So that echo-signal is received machine reception；
The echo signal intensity I being calculated according to the 17th steps, calculate the manual gain value of ISAR radar
MGC value range, shown in calculation method such as formula (8):
Wherein IminFor the receivable echo signal intensity of minimum, ImaxFor the corresponding echo signal intensity of the saturation of receiver；
19th step, the ISAR that the practical PRF and actual transmission pulse width, the 14th step that select after the tenth step are obtained
Radar system echo initial time Ts, the obtained ISAR radar manual gain of the obtained antenna wave position of the 15th step, the 18th step
ISAR radar posture is arranged by the scanning mode of the 15th step, by the starting of the imaging obtained in the 5th step in control gain value MGC
Moment and finish time carry out ISAR radar imagery.
Preferably, in the first step, the interval of orbit parameter renewable time and imaging moment is no more than 12 hours, for guaranteeing
The accuracy of extraterrestrial target orbital prediction.
Preferably, in second step, sensor type is set as rectangle, and horizontal half-angle is arranged between 0.005 °~0.01 °.
Preferably, in the 15th step, the azimuth for realizing that four-step calculation obtains is horizontally rotated by aerial mechanical, is passed through
The elevation angle that four-step calculation obtains is realized in aerial mechanical inclination and antenna electric scanning.
Preferably, in the 15th step, machinery horizontally rotates Adjustment precision 1 order of magnitude at least smaller than radar beam width.
It estimates imaging indicators, estimates imaging performance.
Range resolution:
Range resolution is related to system bandwidth, is by the distance resolution that acquisition target is imaged in ISAR
Wherein BrFor signal bandwidth, after carrying out windowing process, resolution ratio can be made slightly to reduce.
Azimuth resolution:
Accumulation angle is related with signal wavelength and effectively for the azimuth resolution of ISAR imaging
Wherein δ is effectively to accumulate angle, is calculate by the following formula to obtain
Wherein RsDistance for imaging initial time ISAR radar to target to be imaged, ReFor finish time ISAR thunder is imaged
Reach the distance of target to be imaged, RsrFor imaging initial time satellite position to be imaged finish time satellite position between away from
From.
Signal-to-noise ratio
The signal noise ratio (snr) of image finally obtained can be estimated by following formula:
Wherein k is Boltzmann constant, and T is receiver noise temperature, FnFor receiver noise factor, TSWhen to be imaged total
Between.
Embodiment:
This part carries out test imaging to international space station (ISS) by practical ISAR system, verifies proposed by the present invention
The validity of System Parameter Design method.The state that the input parameter list and North American Air Defense Command provided first according to table 1 is announced
Border space station orbit information, by method proposed by the present invention, parameter needed for calculating ISAR imaging the results are shown in Table 2.Then basis
Radar antenna mechanical scanning and electric scanning angle is arranged in parameters obtained, ISAR working state of system and imaging time is arranged, and right
Imaging expected results are estimated.The finally booting imaging when international space station passes through radar beam overlay area obtains final
Test ISAR image.
Parameter list is inputted in 1 embodiment of subordinate list
Output parameter table in 2 embodiment of subordinate list
| Parameter | Numerical value |
| The imaging starting ephemeris moment | 21 Feb 2016 03:20:43.850 |
| Imaging terminates the ephemeris moment | 21 Feb 2016 03:20:45.168 |
| Azimuth (°) | 138.57 |
| The elevation angle (°) | 53.99 |
| PRF(Hz) | 4683 |
| Transmitted signal bandwidth (MHz) | 240 |
| Fire pulse width (us) | 30 |
| Sample window length (us) | 110.9 |
| It samples initial time (us) | 65.3 |
| Redundancy time (us) | 80.7 |
| Median Detection Range (km) | 496.32 |
| Mechanical scanning angle (°) | 30 |
| Electric scanning angle (°) | 6.01 |
| Data transfer rate (Gbps) | 1.19 |
| Echo signal intensity (dBm) | - 110.78~-117.36 |
| Estimate azimuth resolution (m) | 1.36 |
| Estimate range resolution (m) | 0.63 |
| Signal-to-noise ratio (dB) | 46.53 |
This ISAR test uses the Inverse Synthetic Aperture Radar system of C-band, and place is imaged in Beijing.It is provided according to table 1
Input parameter, system limitation and orbit parameter, the parameters such as target imaging moment, azimuth and the elevation angle are obtained in STK software.
In STK software, virtual earth station's sensor is set by above-mentioned calculated result, it can be by observing the virtual world of imaging moment
Whether space station is in the beam coverage of earth station's sensor, tentatively judges whether calculated result is correct with this.Fig. 2 gives
The relative positional relationship of imaging moment international space station and earth station's sensor is gone out, it is seen that international space station is in wave beam at this time
In coverage area, it was demonstrated that above-mentioned calculated result is correct.It is farthest in available imaging process according to imaging moment location information
It is returned with nearest oblique distance, then the protective redundancy and fire pulse width that rationally design followed by the PRF of zebra figure selection system
Transmitting impulse disturbances are kept away, PRF selection result is as shown in Figure 3.Herein when conditions permit, PRF is selected into height as far as possible, to mention
Hi-vision signal-to-noise ratio is reduced and is obscured, this test PRF is selected as 4683Hz.Then calculate sample window length, sampling initial time
And data transfer rate, judge whether data transfer rate exceeds system limitation.
Then in such a way that mechanical scanning and electric scanning combine, the beam position of demand is realized.Pass through aerial mechanical
Horizontally rotate to obtain demand azimuth, tilt to obtain the demand elevation angle by aerial mechanical, this test machines scanning elevation angle is
30 °, remaining 6.01 ° of elevations angle are realized by antenna electric scanning.Then according to system parameter, estimates echo signal intensity, set accordingly
Set radar system manual gain control MGC value, herein because target scattering characteristics are difficult to accurately obtain, therefore, evaluated error compared with
Greatly, test should properly increase yield value for the first time, guarantee that system is rationally arranged according to imaging results in the effective typing of echo, follow-up test
Yield value.Finally assess the imaging indicators that this test expection can obtain, including resolution ratio and signal-to-noise ratio etc..
According to above-mentioned calculating and analysis as a result, having carried out international space station ISAR imaging, the thunder of international space station is obtained
Up to image, imaging results and international space station target geometry are close, and can pass through its outstanding feature object of image discriminating.This
Experimental evidence design parameter result has successfully carried out ISAR imaging to international space station, this demonstrate that the method for the present invention is effective
Property.
The content being not described in detail in description of the invention is known to the skilled person technology.
Claims (5)
1. a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design, characterized by the following steps:
Step 1: calculating extraterrestrial target running track according to known extraterrestrial target orbit parameter；It is soft in satellite shoot
Virtual extraterrestrial target to be imaged is established in part, and newest orbital data is imported into STK software, updates target track information；
Step 2: a virtual-sensor is arranged for the virtual extraterrestrial target to be imaged that the first step is established, most according to ISAR antenna
Vertical half angle θ is arranged in the range that exposes thoroughlyVHA, vertical half angle θVHACalculation method such as formula (1) shown in:
Wherein ReFor earth radius, H is orbit altitude, θr_maxFor ISAR antenna maximum scan range；
According to ISAR radar present position latitude and longitude coordinates, virtual ground station is established in STK software, by analyze virtually at
Virtual-sensor in the target of image space is to the coverage condition at virtual ground station, and cover time central instant was the top moment, i.e.,
The oblique distance shortest moment；
Step 3: the top moment that crosses for first obtaining second step is set as the imaging center moment, according to actual rings around test site
Border judges whether there is and blocks, and blocks if existing on ISAR radar to the sight of target to be imaged at this time, successively in second step
The imaging moment for avoiding blocking is found within the scope of the obtained cover time, sets imaging center for the imaging moment for avoiding blocking
Moment；
Step 4: the imaging center moment obtained according to third step calculates imaging by the visibility analysis tool of STK software
Central instant virtual ground station to the azimuth and the elevation angle of virtual target to be imaged；
Step 5: a new virtual-sensor is established for virtual ground station in STK software, to simulate ISAR radar system,
The vertical half-angle of new virtual-sensor is the half for the antenna beamwidth that expectation target to be imaged passes through direction, and new is virtual
The horizontal half-angle of sensor is the half of the beam angle of another dimension of antenna；The direction of new virtual-sensor presses four-step calculation
Obtained azimuth and elevation angle setting；By analysis virtual ground station sensor to the coverage condition of virtual target to be imaged, obtain
Enter moment and departure time to Target Traversing radar beam to be imaged, the initial time as this imaging is at the end of
It carves；
Step 6: passing through the visible of STK software according to this initial time being imaged and finish time that the 5th step is calculated
Property analysis tool, calculate imaging initial time and finish time ISAR radar to target to be imaged nearest oblique distance RnWith it is farthest tiltedly
Away from Rf；
Step 7: the farthest oblique distance R being calculated in the 6th stepfWith nearest oblique distance RnBoth ends symmetrically increase protective redundancy oblique distance Rr,
For the ISAR radar return window Design of length and PRF selection in subsequent step；
Step 8: ISAR radar initial transmissions pulse width T is arranged according to the limitation of the duty ratio of ISAR radar and data transfer ratep；
Step 9: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith farthest oblique distance Rf, the
The protective redundancy oblique distance R that seven steps obtainr, ISAR radar initial transmissions pulse width T that the 8th step obtainsp, calculate ISAR radar
Emit impulse disturbances band section, shown in calculation method such as formula (2):
Wherein c is the light velocity, and N transmitting receives pulse daley number, and PRT is the transmitting pulse spacing of ISAR radar；
According to formula (2), by zebra figure radar transmitted pulse interference fringe Interval selecting PRT, it is obtained PRT is inverted
To ISAR radar PRF；
Step 10: the ISAR radar initial transmissions pulse width T being arranged according to the 8th steppThe ISAR radar obtained with the 9th step
PRF calculates ISAR radar duty ratio Dc, shown in calculation method such as formula (3)
Dc=Tp*PRF (3)
Then judge duty ratio DcWhether exceed the ISAR radar duty ratio upper limit, if exceeding, the 8th step is returned to, otherwise, by ISAR
Radar initial transmissions pulse width TpIt is determined as actual transmission pulse width, the ISAR radar PRF that the 9th step obtains is determined as
Practical PRF, and carry out in next step；
Step 11: nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarnWith farthest oblique distance Rf,
The protective redundancy oblique distance R that 7th step obtainsr, fire pulse width T that the 8th step obtainsp, calculate ISAR radar return window length
Tw, shown in calculation method such as formula (4):
Step 12: ISAR radar return window length is calculated in the practical PRF and the 11st step that are selected according to the tenth step, calculate
Data transfer rate Dr, shown in calculation method such as formula (5):
Dr=(2*fs*Qn*Tw*BAQ+An*Qn)*PRF (5)
Wherein fsIt is distance to sample frequency, QnQuantization digit, BAQFor data compression rate, AnTo assist data bits；
13rd step, the data transfer rate D being calculated according to the 12nd steprAbility is stored and transmitted with ISAR radar system data, is sentenced
Disconnected data transfer rate DrWhether exceed ISAR radar system data and store and transmit ability, if exceeding, returns to the 7th step, otherwise, into
Row is in next step；
14th step, the nearest oblique distance R of the target to be imaged being calculated according to the 6th step to ISAR radarn, the 7th step obtains
Protective redundancy oblique distance RrThe PRT selected with the 9th step calculates ISAR radar return initial time Ts, calculation method such as formula (6) institute
Show:
15th step, in such a way that mechanical scanning and ISAR radar antenna electric scanning combine, the wave beam of adjustment imaging needs
It is directed toward；Antenna wave position is found according to electric scanning angle, so that ISAR radar is to the sight of target to be imaged closest to beam center；
16th step, the antenna wave position obtained according to the 15th step, the sight and wave beam of calculating ISAR radar to target to be imaged
The angle at center, and then obtain corresponding antenna gain G；
17th step calculates the receiver inlet echo signal intensity I in addition to manual gain control gain value MGCs, calculating side
Shown in method such as formula (7):
Wherein PtFor peak transmitted power, λ is carrier wavelength, and σ is target state estimator radar cross section, GrcFor except manual gain control
Receiving channel overall gain outside yield value MGC processed, the loss of L transmission link, R are ISAR radar to the average value of target oblique distance, can
It is approximately (Rn-Rf)/2；
The manual gain value MGC of ISAR radar is arranged according to the signal range of receiving of receiver in 18th step, so that
Echo-signal is received machine reception；
The echo signal intensity I being calculated according to the 17th steps, calculate the manual gain value MGC value of ISAR radar
Range, shown in calculation method such as formula (8):
Wherein IminFor the receivable echo signal intensity of minimum, ImaxFor the corresponding echo signal intensity of the saturation of receiver；
19th step, the ISAR radar that the practical PRF and actual transmission pulse width, the 14th step that select after the tenth step are obtained
System echoes initial time Ts, the obtained manual gain control system of ISAR radar of the obtained antenna wave position of the 15th step, the 18th step
ISAR radar posture is arranged by the scanning mode of the 15th step, by the initial time of the imaging obtained in the 5th step in yield value MGC
ISAR radar imagery is carried out with finish time.
2. a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design according to claim 1, feature exist
In: in the first step, the interval of orbit parameter renewable time and imaging moment is no more than 12 hours.
3. a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design according to claim 1, feature exist
In: in the second step, sensor type is set as rectangle, and horizontal half-angle is arranged between 0.005 °~0.01 °.
4. a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design according to claim 1, feature exist
In: in the 15th step, the azimuth for realizing that four-step calculation obtains is horizontally rotated by aerial mechanical, passes through aerial mechanical
The elevation angle that four-step calculation obtains is realized in inclination and antenna electric scanning.
5. a kind of extraterrestrial target inverse synthetic aperture radar imaging Parameters design according to claim 4, feature exist
In: in the 15th step, machinery horizontally rotates Adjustment precision 1 order of magnitude at least smaller than radar beam width.
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| CN112505694B (en) * | 2020-10-30 | 2023-07-28 | 北京空间飞行器总体设计部 | Space target imaging method of on-orbit SAR satellite |
| CN116699613B (en) * | 2023-08-04 | 2023-10-13 | 中国科学院空天信息创新研究院 | On-orbit accurate calculation method for scanning mode imaging starting time |
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