CN114137519A - High-resolution SAR imaging parameter calculation method - Google Patents

High-resolution SAR imaging parameter calculation method Download PDF

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CN114137519A
CN114137519A CN202111143238.6A CN202111143238A CN114137519A CN 114137519 A CN114137519 A CN 114137519A CN 202111143238 A CN202111143238 A CN 202111143238A CN 114137519 A CN114137519 A CN 114137519A
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repetition frequency
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程博文
郝梁
赵思阳
蒋帅
刘伟伟
庞亚龙
田苗苗
栾申申
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Beijing Institute of Spacecraft System Engineering
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Abstract

The invention provides a resolution SAR imaging parameter calculation method, which takes parameters such as imaging scene position, imaging synthetic aperture duration, sliding factor, minimum repetition frequency, maximum repetition frequency and the like as input conditions, respectively calculates and obtains zero Doppler center time and imaging start and end time of an imaging scene through a satellite-ground geometric model, selects repetition frequency which accords with SAR imaging performance indexes as imaging parameters and outputs the imaging parameters in an imaging arc section according to a fixed time step length, reduces calculation time expenditure, avoids returning to an iterative search process, saves storage resources, is suitable for being realized in a satellite-borne environment under the condition of resource limitation, and is convenient for deployment and implementation of satellite-borne hardware; the invention can realize the sliding bunching imaging modes with different imaging resolutions and imaging widths by modifying parameters such as imaging synthetic aperture duration, sliding factors, minimum repetition frequency, maximum repetition frequency and the like; and the performance index calculation is integrated, and the wave position design integration characteristic is achieved.

Description

High-resolution SAR imaging parameter calculation method
Technical Field
The invention belongs to the technical field of radar system design, and particularly relates to a method for calculating a resolution SAR imaging parameter, which is suitable for wave position design in an SAR satellite sliding bunching mode for realizing high-resolution imaging through whole satellite attitude maneuver.
Background
In order to realize high-resolution imaging and guarantee a certain azimuth mapping width, a high-resolution SAR satellite generally adopts a sliding beam bunching mode, the sliding speed of a beam footprint on the ground is reduced by controlling the azimuth rotation angle of an antenna beam, and meanwhile, the synthetic aperture time of an imaging point is increased, so that the high-resolution imaging is realized. During the satellite rotation, due to the fact that echo range migration is large, in terms of wave level design, a single repetition frequency imaging realization mode adopted in a traditional satellite-borne SAR is not effective any more, the repetition frequency changing design must be carried out in the whole imaging process, and effective reception of echoes is guaranteed by moving an echo window. Figure 1 shows the working of sliding bunching. At present, the sliding spotlight mode is successfully applied to a TerrraSAR-X satellite in Germany, and can realize the imaging of 0.25m resolution in the azimuth direction.
Wave position design of the existing satellite-borne SAR sliding bunching mode is given by a ground computer through a repeated iteration simulation mode based on a high-precision satellite-ground geometric model. For example, the institute 201910549798.8 of space radio technology in west ampere discloses a method for designing a segment variable repetition frequency time sequence of an ultra-high resolution spaceborne SAR, which comprises the steps of segmenting the azimuth direction by adopting a fixed slant range span mode, designing an azimuth echo receiving window and a working repetition frequency, verifying a variable repetition frequency design result by a simulation means, and readjusting the slant range span if the variable repetition frequency design result does not meet the condition until the echo of the whole scene can be effectively received. However, the method has the problems that the number of the segments is large, the repetition frequency calculation times are large, the calculation amount is large, meanwhile, in the repeated iteration process, the intermediate calculation result needs to be stored, the requirement on storage resources is high, and the like, and the method is not suitable for being implemented in a satellite-borne environment under the condition of limited resources.
Disclosure of Invention
In view of this, the present invention provides a method for calculating a resolution SAR imaging parameter, which reduces the calculation time overhead, avoids a search process of returning iteration, saves storage resources, and facilitates the deployment and implementation of satellite-borne hardware.
A high resolution SAR imaging parameter calculation method comprises the following steps:
step (1), receiving the position of the scene including imaging through a satellite-ground link
Figure BDA0003284783010000011
Calculating parameters of imaging synthetic aperture time length T, sliding factor A, minimum repetition frequency and maximum repetition frequency;
step (2) extrapolating the satellite orbit position according to the set time step length to obtain the satellite position at each moment
Figure BDA0003284783010000021
And velocity
Figure BDA0003284783010000022
Step (3) according to the position of the imaging scene
Figure BDA0003284783010000023
And extrapolated satellite positions
Figure BDA0003284783010000024
And velocity
Figure BDA0003284783010000025
Calculating satellite Doppler frequency at each time
Figure BDA0003284783010000026
And selecting the Doppler frequency sign change time as the zero Doppler time of the imaging scene
Figure BDA0003284783010000027
Step (4) taking the zero Doppler time of the scene
Figure BDA0003284783010000028
As a center, calculating the imaging start T according to the total imaging duration T of the sliding bunching modesAnd an end time Te；
Step (5), sliding factors according to sliding bunching modes and imaging target positions
Figure BDA0003284783010000029
Calculating virtual center point coordinates for sliding spotlight patterns
Figure BDA00032847830100000210
Step (6), according to the imaging start time and the imaging end time obtained in the step (4) and the virtual center point coordinate obtained in the step (5)
Figure BDA00032847830100000211
Obtaining the short-distance point slant distance and the long-distance point slant distance of the antenna in the distance direction according to the satellite position and the antenna beam width within the set time step from the starting time to the ending time;
step (7), according to the minimum repetition frequency and the maximum repetition frequency in the imaging mode, sequentially selecting PRFs (pseudo random frequencies) which accord with constraint conditions from small to large as system repetition frequency parameters according to a set time step;
step (8), the system repetition frequency parameters output in the step (7) are firstly subjected to SAR performance index screening on the system repetition frequency parameters ranked first, if the system repetition frequency parameters do not meet the conditions, the step (7) is returned, second system repetition frequency parameters are obtained, and whether the system repetition frequency parameters meet the SAR performance indexes or not is judged; and repeating the steps until the first system repetition frequency parameter which accords with the SAR performance index is found.
Further, in the step (7), the PRF is selected according to the following constraints:
Figure BDA00032847830100000212
in the formula, int () is a rounding function for fetching an integer part of data; frac () is used to fetch the fractional part; rminAnd RmaxThe oblique distances of the near distance points and the far distance points are respectively; t ispIs the width of the echo, TgThe protection time is determined by the SAR system design.
Preferably, in the step (8), the PRF is selected according to the position ambiguity and the distance ambiguity index.
Preferably, in the step (8), the calculation formula of the orientation ambiguity filtering is as follows:
Figure BDA0003284783010000031
in the formula, B is the azimuth Doppler bandwidth and is determined by SAR load design; f is the Doppler frequency, fdeEstimating deviation for equivalent Doppler center frequency, wherein m is the sequence number of the azimuth fuzzy area and is given by an antenna directional diagram;
Figure BDA0003284783010000032
expressed as a function of the antenna azimuth two-way gain:
Figure BDA0003284783010000033
where V is the satellite-to-ground equivalent speed, DaIs the azimuth antenna dimension.
Preferably, in the step (8), the calculation formula of the distance ambiguity filtering is as follows:
Figure BDA0003284783010000034
in the formula, DWP represents the echo delay time, τwThe width of an echo data window is defined, and n is a sequence number of a fuzzy area and is given by an antenna directional diagram; tau is echo delay time, R (tau) is slope distance, i.e. stepThe short distance point slope distance R obtained in the step (6)minAnd a remote point slope distance Rmax，σ0(τ) is the ground target backscattering coefficient; thetai(τ) represents the angle of incidence; g (τ) is a two-way gain function of the range antenna, expressed as:
Figure BDA0003284783010000035
where λ is the operating wavelength, DrIs the distance dimension to the antenna, and α (τ) is the viewing angle corresponding to R (τ).
Preferably, in the step (3), the Doppler frequency is set
Figure BDA0003284783010000036
The calculation formula is as follows:
Figure BDA0003284783010000037
Figure BDA0003284783010000038
is the imaging scene velocity vector under the geocentric inertial coordinate system, lambda is the carrier wave wavelength, RstIs the distance between the satellite and the object located in the center of the imaged scene.
Preferably, the set time is 1 s.
Preferably, in the step (6), the estimating of the slant range between the satellite position and the virtual center point coordinate at each time includes:
knowing the satellite position:
Figure BDA0003284783010000041
the nearest and farthest beam pointing vectors of the antenna in the distance direction obtained according to the beam width of the antenna are respectively as follows:
Figure BDA0003284783010000042
establishing a space linear equation:
Figure BDA0003284783010000043
wherein, a is the equator radius of the earth, c is the polar radius of the earth, l, m, n are direction numbers, and the specific expression is as follows:
Figure BDA0003284783010000044
when X, Y, Z are
Figure BDA0003284783010000045
Then, the coordinate position (x, y, z) of the nearest beam in the earth-fixed coordinate system can be obtained by solving according to the space linear equation, and is recorded as (x)1，y1，z1) When X, Y, Z are
Figure BDA0003284783010000046
Then, the coordinate position (x, y, z) of the far beam in the earth-fixed coordinate system can be obtained by solving according to the space linear equation, and is recorded as (x)2，y2，z2) And then the satellite coordinates in the satellite earth-fixed coordinate system
Figure BDA0003284783010000047
Simultaneous obtaining of short-range point slope distance RminAnd a remote point slope distance RmaxRespectively as follows:
Figure BDA0003284783010000051
Figure BDA0003284783010000052
the invention has the following beneficial effects:
the invention provides a resolution SAR imaging parameter calculation method, which takes parameters such as imaging scene position, imaging synthetic aperture duration, sliding factor, minimum repetition frequency, maximum repetition frequency and the like as input conditions, respectively calculates and obtains zero Doppler center time and imaging start and end time of an imaging scene through a satellite-ground geometric model, selects repetition frequency which accords with SAR imaging performance indexes as imaging parameters and outputs the imaging parameters in an imaging arc section by fixed time step length, reduces calculation time expenditure, avoids returning to an iterative search process, saves storage resources, is suitable for being realized in a satellite-borne environment under the condition of resource limitation, and is convenient for deployment and implementation of satellite-borne hardware.
The invention can realize the sliding bunching imaging modes with different imaging resolutions and imaging widths by modifying parameters such as imaging synthetic aperture duration, sliding factors, minimum repetition frequency, maximum repetition frequency and the like; and the performance index calculation is integrated, and the wave position design integration characteristic is achieved.
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FIG. 1 is a schematic flow diagram of the process of the present invention;
FIG. 2 is a SAR satellite sliding bunching mode imaging model;
FIG. 3 is a range of pitch variation;
FIG. 4 shows the result of the selection of the re-frequency varying parameter;
FIG. 5 is a slider point target distribution;
fig. 6 is a sliding focus point imaging result.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
In order to realize high-resolution imaging, the existing SAR satellites for realizing high-resolution imaging through whole-satellite attitude maneuver generally adopt a sliding beam-bunching imaging mode. In this mode, since the range of the scene skew is changed greatly, so that the echo window determined by a single repetition frequency (PRF) cannot completely receive the scene echo, it is necessary to adopt a variable repetition frequency mode to form receiving windows located at different positions to ensure effective reception of the echo. The invention designs a high-resolution SAR imaging parameter on-orbit calculation method based on the sliding bunching working characteristics adopted by a satellite, mainly solves the problem of self-adaptive adjustment of system repetition frequency caused by the change of the slant range, and has the characteristics of low calculation and storage resource cost and convenience for deploying and implementing satellite-borne hardware.
The technical solution of the invention is as follows:
an on-orbit calculation method for high-resolution SAR imaging parameters mainly comprises the following steps:
step 1: receiving imaged scene location over satellite-to-ground link
Figure BDA0003284783010000061
Calculating parameters such as imaging synthetic aperture time length T, sliding factor A, minimum repetition frequency, maximum repetition frequency and the like;
step 2: extrapolating the satellite orbit position by a fixed time step length (such as 1 second) to obtain the satellite position at each moment
Figure BDA0003284783010000062
And velocity
Figure BDA0003284783010000063
And step 3: according to the position of the imaged scene
Figure BDA0003284783010000064
And extrapolated satellite positions
Figure BDA0003284783010000065
And velocity
Figure BDA0003284783010000066
Calculating the satellite Doppler frequency f at each timedcAnd selecting the Doppler frequency sign change time to determine the Doppler frequency sign change time as the zero Doppler time of the imaging scene
Figure BDA0003284783010000067
The doppler frequency calculation formula is as follows:
Figure BDA0003284783010000068
in the formula
Figure BDA0003284783010000069
Is a satellite position vector under the earth center inertial coordinate system,
Figure BDA00032847830100000610
is an imaging scene position vector under the geocentric inertial coordinate system,
Figure BDA00032847830100000611
is the velocity vector of the satellite under the earth center inertial coordinate system,
Figure BDA00032847830100000612
is the imaging scene velocity vector under the geocentric inertial coordinate system, lambda is the carrier wave wavelength, RstIs the distance between the satellite and the object located in the center of the imaged scene.
And 4, step 4: at zero Doppler time of the scene
Figure BDA00032847830100000613
As a center, calculating the imaging start T according to the total imaging duration T of the sliding bunching modesAnd an end time TeAnd satisfies the following conditions:
Figure BDA00032847830100000614
and 5: sliding factor and imaging target location according to sliding bunching mode
Figure BDA00032847830100000615
Calculating virtual center point coordinates for sliding spotlight patterns
Figure BDA00032847830100000616
Figure BDA00032847830100000617
Wherein A is a sliding factor determined by the upper note parameter,
Figure BDA00032847830100000618
is an imaging target position vector under the geocentric inertial coordinate system,
Figure BDA00032847830100000619
a satellite position vector at zero doppler time.
Step 6: according to the imaging start time, the imaging end time and the virtual center point coordinate obtained in the steps 3 and 4, in a fixed time step (such as 1 second), calculating the short distance and the long distance of the antenna in the distance direction according to the satellite position and the antenna beam width within the time from the start time to the end time, wherein the calculation method comprises the following steps:
knowing the satellite position:
Figure BDA0003284783010000071
the nearest and farthest beam pointing vectors of the antenna in the distance direction obtained according to the beam width of the antenna are respectively as follows:
Figure BDA0003284783010000072
establishing a space linear equation:
Figure BDA0003284783010000073
wherein, a is 6378140m and c is 6356755m, l, m and n are directions, and the specific expression is as follows:
Figure BDA0003284783010000074
when X, Y, Z are
Figure BDA0003284783010000075
Then, the coordinate position of the nearest beam in the earth-fixed coordinate system can be obtained by solving according to the space linear equation and is recorded as (x)1，y1，z1) When X, Y, Z are
Figure BDA0003284783010000076
Then, the coordinate position of the far beam in the earth-fixed coordinate system can be obtained by solving according to a space linear equation and is recorded as (x)2，y2，z2) And then the satellite coordinates in the satellite earth-fixed coordinate system
Figure BDA0003284783010000077
Simultaneous obtaining of short-range point slope distance RminAnd a remote point slope distance RmaxRespectively as follows:
Figure BDA0003284783010000078
Figure BDA0003284783010000081
and 7: and according to the minimum repetition frequency and the maximum repetition frequency in the imaging mode, sequentially selecting PRFs (pulse repetition frequencies) meeting the constraint condition from small to large as a system repetition frequency parameter by using a fixed step length (such as 1). Wherein the PRF is selected with the constraints of:
Figure BDA0003284783010000082
where C represents the speed of light and int () is a rounding function, which is used to fetch the integer part of the data; frac () is used to fetch the fractional part; rminAnd RmaxThe slope distance of the near point and the slope distance of the far point are given by the step 5; t ispIs the width of the echo, TgThe protection time is determined by the SAR system design.
And 8: and (4) screening SAR performance indexes of each repetition frequency parameter output in the step (7), and if the repetition frequency parameters do not meet the conditions, repeating the step (7). The method specifically comprises the following steps:
(1) the orientation ambiguity screening method comprises the following steps:
Figure BDA0003284783010000083
in the formula (f)prfThe frequency corresponding to the wave position is represented and is the reciprocal of PRF; b is the azimuth Doppler bandwidth, and is determined by SAR load design; f is the Doppler frequency, calculated in step 3, fdeEstimating deviation for equivalent Doppler center frequency, wherein m is the sequence number of the azimuth fuzzy area and is given by an antenna directional diagram;
Figure BDA0003284783010000084
expressed as a function of the antenna azimuth two-way gain:
Figure BDA0003284783010000085
where V is the satellite-to-ground equivalent speed, DaIs the azimuth antenna size;
(2) the distance ambiguity screening method comprises the following steps:
Figure BDA0003284783010000086
in the formula, DWP represents the echo delay time, τwThe width of an echo data window is defined, and n is a sequence number of a fuzzy area and is given by an antenna directional diagram; tau is echo delay time, R (tau) is slope distance R which is the slope distance R of the near point obtained in the step (6)minAnd a remote point slope distance Rmax，σ0(τ) is the ground target backscattering coefficient; thetai(τ) represents the angle of incidence; g (τ) is a two-way gain function of the range antenna, expressed as:
Figure BDA0003284783010000091
in the formula, alphanAnd alphafRespectively representing a proximal viewing angle and a distal viewing angle; λ is the operating wavelength, DrIs the distance dimension to the antenna, and α (τ) is the viewing angle corresponding to R (τ).
Example (b):
according to the method, a set of high-resolution SAR imaging parameters are designed according to given input system requirement parameters, and the effectiveness of the method is verified through system performance obtained through analysis.
According to the method of the present invention, imaging parameters are calculated, and system input parameters are shown in the following table.
Table 1 attached examples input parameter table
Figure BDA0003284783010000092
Figure BDA0003284783010000101
The zero doppler time calculated by step 3 is 56 seconds according to the satellite orbit parameters given herein, and the start time is 48 seconds and the end time is 64 seconds according to the synthetic aperture duration input parameters and the calculation method of step 4.
The calculated near point slant distance and far point slant distance according to the steps 5-6 are shown in fig. 3, and the variable repetition frequency selection result according to the steps 7-8 is shown in fig. 4.
The generated variable repetition frequency parameter information is led into echo simulation software, the simulation scene point target is set as shown in figure 5, the target scene width is about 25km multiplied by 25km, each target can be completely covered by a beam, and the accumulation time of each point target is ensured.
The imaging adopts Deramping + distance NCS to realize sliding bunching imaging. The imaging algorithm comprises azimuth anticline preprocessing and distance NCS algorithm processing, and a high-resolution variable repetition frequency imaging processing algorithm is designed according to the variable repetition frequency characteristic. The main flow of the algorithm is to interpolate the variable repetition frequency signal into a uniform signal, then to perform azimuth signal up-sampling, then to perform distance compression and distance migration correction by using the NCS algorithm, and finally to perform azimuth compression.
The final imaging results are shown in the following figures, where it can be seen that the point targets are well focused. The imaging resolution, the integral sidelobe ratio and the peak sidelobe ratio meet the requirements.
Attached table 2 point target imaging result index
Figure BDA0003284783010000102
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A high resolution SAR imaging parameter calculation method is characterized by comprising the following steps:
step (1), receiving the position of the scene including imaging through a satellite-ground link
Figure FDA0003284783000000011
Calculating parameters of imaging synthetic aperture time length T, sliding factor A, minimum repetition frequency and maximum repetition frequency;
step (2) extrapolating the satellite orbit position according to the set time step length to obtain the satellite position at each moment
Figure FDA0003284783000000012
And velocity
Figure FDA0003284783000000013
Step (3) according to the position of the imaging scene
Figure FDA0003284783000000014
And extrapolated satellite positions
Figure FDA0003284783000000015
And velocity
Figure FDA0003284783000000016
Calculating satellite Doppler frequency at each time
Figure FDA0003284783000000017
And selecting the Doppler frequency sign change time as the zero Doppler time of the imaging scene
Figure FDA0003284783000000018
Step (4) taking the zero Doppler time of the scene
Figure FDA0003284783000000019
As a center, calculating the imaging start T according to the total imaging duration T of the sliding bunching modesAnd an end time Te；
Step (5), sliding factors according to sliding bunching modes and imaging target positions
Figure FDA00032847830000000110
Calculating virtual center point coordinates for sliding spotlight patterns
Figure FDA00032847830000000111
Step (6), according to the imaging start time and the imaging end time obtained in the step (4) and the virtual center point coordinate obtained in the step (5)
Figure FDA00032847830000000112
Obtaining the short distance point of the antenna in the distance direction according to the satellite position and the antenna beam width within the time from the starting time to the ending time by the set time step lengthSkew distance and remote point skew distance;
step (7), according to the minimum repetition frequency and the maximum repetition frequency in the imaging mode, sequentially selecting PRFs (pseudo random frequencies) which accord with constraint conditions from small to large as system repetition frequency parameters according to a set time step;
step (8), the system repetition frequency parameters output in the step (7) are firstly subjected to SAR performance index screening on the system repetition frequency parameters ranked first, if the system repetition frequency parameters do not meet the conditions, the step (7) is returned, second system repetition frequency parameters are obtained, and whether the system repetition frequency parameters meet the SAR performance indexes or not is judged; and repeating the steps until the first system repetition frequency parameter which accords with the SAR performance index is found.
2. The high resolution SAR imaging parameter calculation method according to claim 1, wherein in said step (7), the PRF is selected with the constraint that:
Figure FDA00032847830000000113
wherein C represents the speed of light; int () is a rounding function for taking the integer part of the data; frac () is used to fetch the fractional part; rminAnd RmaxThe oblique distances of the near distance points and the far distance points are respectively; t ispIs the width of the echo, TgThe protection time is determined by the SAR system design.
3. The method for calculating high resolution SAR imaging parameters according to claim 1 or 2, wherein in said step (8), the PRF is selected according to an index of azimuth ambiguity and distance ambiguity.
4. The method for calculating the parameters of the high resolution SAR imaging according to claim 3, wherein in said step (8), the calculation formula of the orientation ambiguity filtering is:
Figure FDA0003284783000000021
in the formula (f)prfThe frequency corresponding to the wave position is represented and is the reciprocal of PRF; b is the azimuth Doppler bandwidth, and is determined by SAR load design; f is the Doppler frequency, fdeEstimating deviation for equivalent Doppler center frequency, wherein m is the sequence number of the azimuth fuzzy area and is given by an antenna directional diagram;
Figure FDA0003284783000000022
expressed as a function of the antenna azimuth two-way gain:
Figure FDA0003284783000000023
where V is the satellite-to-ground equivalent speed, DaIs the azimuth antenna dimension.
5. The method for calculating the parameters of the high resolution SAR imaging according to claim 3, wherein in the step (8), the calculation formula of the distance ambiguity filtering is as follows:
Figure FDA0003284783000000024
in the formula, DWP represents the echo delay time, τwThe width of an echo data window is defined, and n is a sequence number of a fuzzy area and is given by an antenna directional diagram; tau is echo delay time, R (tau) is slope distance, namely the slope distance R of the near point obtained in the step (6)minAnd a remote point slope distance Rmax，σ0(τ) is the ground target backscattering coefficient; thetai(τ) represents the angle of incidence; g (τ) is a two-way gain function of the range antenna, expressed as:
Figure FDA0003284783000000025
in the formula, alphanAnd alphafRespectively representing a near-end view and a far-end viewAn angle; λ is the operating wavelength, DrIs the distance dimension to the antenna, and α (τ) is the viewing angle corresponding to R (τ).
6. The high resolution SAR imaging parameter calculation method according to claim 1 or 2, characterized in that in the step (3), Doppler frequency fdciThe calculation formula is as follows:
Figure FDA0003284783000000031
Figure FDA0003284783000000032
is the imaging scene velocity vector under the geocentric inertial coordinate system, lambda is the carrier wave wavelength, RstIs the distance between the satellite and the object located in the center of the imaged scene.
7. The high resolution SAR imaging parameter calculation method according to claim 1 or 2, wherein said set time is 1 s.
8. The method for calculating the high resolution SAR imaging parameters according to claim 1 or 2, wherein in the step (6), the estimation of the slant range between the satellite position and the virtual center point coordinate at each time is specifically as follows:
knowing the satellite position:
Figure FDA0003284783000000033
the nearest and farthest beam pointing vectors of the antenna in the distance direction obtained according to the beam width of the antenna are respectively as follows:
Figure FDA0003284783000000034
and
Figure FDA0003284783000000035
establishing a space linear equation:
Figure FDA0003284783000000036
wherein, a is the equator radius of the earth, c is the polar radius of the earth, l, m, n are direction numbers, and the specific expression is as follows:
Figure FDA0003284783000000037
when X, Y, Z are
Figure FDA0003284783000000041
Then, the coordinate position (x, y, z) of the nearest beam in the earth-fixed coordinate system can be obtained by solving according to the space linear equation, and is recorded as (x)1，y1，z1) When X, Y, Z are
Figure FDA0003284783000000042
Then, the coordinate position (x, y, z) of the far beam in the earth-fixed coordinate system can be obtained by solving according to the space linear equation, and is recorded as (x)2，y2，z2) And then the satellite coordinates in the satellite earth-fixed coordinate system
Figure FDA0003284783000000043
Simultaneous obtaining of short-range point slope distance RminAnd a remote point slope distance RmaxRespectively as follows:
Figure FDA0003284783000000044
Figure FDA0003284783000000045
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CN115657031A (en) * 2022-12-12 2023-01-31 中国科学院空天信息创新研究院 Image domain moving target detection method based on long-time sliding bunching
CN116087953A (en) * 2023-03-20 2023-05-09 中国科学院空天信息创新研究院 Satellite-borne SAR multi-target imaging parameter design method
CN116699613A (en) * 2023-08-04 2023-09-05 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

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115657031A (en) * 2022-12-12 2023-01-31 中国科学院空天信息创新研究院 Image domain moving target detection method based on long-time sliding bunching
CN115657031B (en) * 2022-12-12 2023-03-07 中国科学院空天信息创新研究院 Image domain moving target detection method based on long-time sliding bunching
CN116087953A (en) * 2023-03-20 2023-05-09 中国科学院空天信息创新研究院 Satellite-borne SAR multi-target imaging parameter design method
CN116699613A (en) * 2023-08-04 2023-09-05 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
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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