KR20110097277A - Synthetic aperture radar image forming simulation system and method - Google Patents

Abstract

The present invention relates to a simulation system and method for forming an image of a point target / multi target / distributed target for verifying the performance of the SAR system, and more particularly, operation modes (Strip, Spotlight, Scan) for obtaining an image of the SAR After setting the satellite and the shooting time of the satellite, input the observation time of SAR to calculate the position of the satellite and the target for each simulation time, and set the amount of change of the satellite's error factor (Antenna Pointing Error, Jitter, Drift) SAR image is formed based on the system parameters such as the forward and backward paths of the satellite, the phase delay time for each pulse, the antenna gain value, the window filter value, and the values of the I and Q channels received in each pulse. The present invention relates to a SAR image forming simulation system and method.
The SAR image forming simulation system according to the present invention includes a project package unit for generating or managing a simulation scenario of SAR for image acquisition from a satellite; An orbit package unit for designing satellite orbits from Kepler orbital elements for the satellites and predicting orbital elements at arbitrary times; A SAR hardware package unit configured to calculate an index range affected by the antenna using the antenna parameters of the SAR, and model the received signal to reflect the influence of the antenna performance and error factors; A target package unit for generating a reflection map using virtual ground clutter information when simulating the received signal of the SAR; A simulation package unit configured to generate and process a simulated signal using the orbital element, the payload information, and the clutter information for the satellite to execute a simulation according to an operation mode; And a display package unit for forming a final SAR image from the simulation signal according to the simulation, performing geometric / radial quality evaluation on the formed image, and displaying or storing the result on a screen.
According to the present invention, Chirp Pulps generation modeling can be implemented by simulating a wideband pulse generation and compression technique including amplitude / phase stability, rate of change, and the like of an LFM pulse in the range direction. In addition, the spotlight mode can be used to form a high resolution image to improve resolution in the azimuth direction. In addition, we analyze the effects of SAR satellite system design parameters on the final image to improve SAR satellite system design capability, and simulate and analyze various parameters to create a simulation program for predicting and displaying the final image quality of the designed satellites and sensors. Can be implemented.

Description

Synthetic aperture radar image forming simulation system and method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simulation system and method for forming an image of a point target / multi target / distributed target for verifying the performance of a synthetic aperture radar (SAR) system. After inputting the SAR observation time, the satellite position and the target position are calculated for each simulation time, the satellite change error factor (Antenna Pointing Error, Jitter, Drift) is set, the satellite's forward path and SAR image forming simulation system and method for forming SAR image based on system parameters such as backward path, phase delay time for each pulse, antenna gain value, value of I channel and Q channel received in each pulse It is about.

SAR (Synthetic Aperture Radar) signal processing technology has been introduced since the 1960s and has been changing a lot. Early SAR algorithms, called unfocused SARs, mapped the data received by the antenna to a two-dimensional image plane without any special signal processing. After that, it has been developed to obtain high resolution video images through focused SAR signal processing that changes the phase of the received signal.

As the computer's processing speed gets faster, even if SAR data is processed digitally, real-time processing is possible depending on the amount of data. It became possible to get. Therefore, research on various signal processing algorithms and various applications that are made possible by digitally processing SAR data has emerged as a very important field of radar signal processing. Typical SAR image processing algorithms include Range Doppler Algorithm (RDA), Chip Scaling Algorithm (CSA), Frequency Scaling Algorithm (FSA), and SPECtral ANalysis method (SPECAN).

In addition, with the development of the SAR system, the technology of collecting earth observation information from aviation and satellite is rapidly developing. The development of SAR image data utilization technology is urgent, and the conversion of utilization technology should accurately predict the surface scattering characteristics of microwaves and develop a simulation model to verify the performance of SAR system.

The acquisition of high resolution SAR images requires different approaches for the rang direction and the azimuth direction, and for the generation of spotlight mode SAR, CW (Continuous Wave) is reflected from the point targets according to the geometrical conditions of the ground surface and the position and rotation angle of the antenna. We need to generate a simulation method of the raw signal data of the SAR system by calculating the phase and amplitude of.

And, for the operation and design of SAR, it is necessary to analyze the impact analysis method by Point Target and the quality of Multi Target or Distributed Target. The existing simulator has a problem that it is impossible to analyze the complete image radar because it provides the analysis function of the point target.

An object of the present invention for solving the above-described problems, after setting the shooting time of the satellite, input the observation time of the SAR to calculate the position of the satellite and the target for each simulation time, and the error influence factor of the satellite (Antenna Pointing Error, Jitter, and Drift), and adjust the system parameters such as the satellite's forward and backward paths, the phase delay time for each pulse, the antenna gain value, and the I and Q channel values received from each pulse. The present invention provides a SAR image forming simulation system and method capable of forming a SAR image based on the present invention.

SAR image formation simulation system according to the present invention for achieving the above object, the project package unit for generating or managing a simulation scenario of SAR for image acquisition from the satellite; An orbit package unit for designing satellite orbits from Kepler orbital elements for the satellites and predicting orbital elements at arbitrary times; A SAR hardware package unit configured to calculate an index range affected by the antenna using the antenna parameters of the SAR, and model the received signal to reflect the influence of the antenna performance and error factors; A target package unit for generating a reflection map using virtual ground clutter information when simulating the received signal of the SAR; A simulation package unit configured to generate and process a simulated signal using the orbital element, the payload information, and the clutter information for the satellite to execute a simulation according to an operation mode; And a display package unit for forming a final SAR image from the simulation signal according to the simulation, performing geometric / radial quality evaluation on the formed image, and displaying or storing the result on a screen.

Also, an operation selector for selecting whether to operate in a strip mode, a scan mode, or a spotlight mode for an operation mode for acquiring an image of the SAR. Additionally included.

The apparatus may further include a satellite error setting unit that defines an error range for the antenna pointing position of the satellite and sets an error of a satellite shift due to external force such as satellite phase shift jitter and solar wind. do.

The simulation package unit generates a raw signal of a point target or a multi target through an operation mode setting process, a satellite error setting process, an orbit propagation process, a propagation pulse delay process, and a return signal calculation process.

The operation mode setting process may include operating in a strip mode, a scan mode, or a spotlight mode for an operation mode for acquiring an image of the SAR. Set the satellite operating mode to select.

In addition, the satellite error setting process, the error range for the positioning point of the antenna of the satellite and defines the error of the satellite (drift) due to the phase shift error (jitter) and the external force including the solar wind of the satellite. do.

In addition, the orbit propagation process calculates the position of the satellite and the position of the target for each simulation time by inputting the observation time of the SAR.

In addition, the propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, calculates the round trip distance between the satellite and the target during the imaging time, and phase delay for each pulse. Calculate

In addition, the return signal calculation process calculates an antenna gain value to be applied for each pulse, and calculates values of an I channel and a Q channel received in each pulse.

In addition, the simulation package unit generates a distributed target raw signal through an orbit propagation process, a propagation pulse delay process, a reflectivity map display process, and an overlapping return signal calculation process.

In addition, the orbit propagation process calculates the position of the satellite and the position of the target for each simulation time by inputting the observation time of the SAR.

In addition, the propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, calculates the round trip distance between the satellite and the target during the imaging time, and phase delay for each pulse. Calculate

In addition, the reflectivity map display process calculates a local projection angle between the signal and the indicator, calculates a shadow area not reflected by each pulse, and calculates a diffusion value of the reflectivity map reflected by each pulse.

The overlap return signal calculation process calculates an antenna gain value to be applied to each pulse, and calculates by overlapping the values of the I channel and the Q channel received in each pulse.

Meanwhile, the SAR image forming simulation method according to the present invention for achieving the above object is a SAR image forming simulation method for processing a raw image signal for a point target / multi target from a satellite, (a) obtaining an image of SAR An operation mode setting step of setting an operation mode to perform the operation mode; (b) a satellite error setting step of defining an error range for an antenna pointing position of a satellite and setting an error of a satellite shift due to an external force including a satellite phase shift jitter and solar wind; (c) an orbit propagation step of calculating a position of the satellite and a position of the target by setting a time when the position of the satellite is closest to the target along the orbit of the satellite and inputting an observation time; (d) a propagation delay that calculates the arrival time of the forward path and the backward path to the satellite, calculates the round trip distance of the satellite and the target during the imaging time, and calculates a phase delay for each pulse; step; And (e) calculating an antenna gain value and a window filter value to be applied to each pulse, and calculating a return signal for calculating the values of the I channel and the Q channel received in each pulse.

Here, in the point target / multi-target raw video signal generated after step (e), phase signals are uniformly distributed, and a phase delay is generated in the center of the raw video signal.

Meanwhile, a SAR image forming simulation method according to the present invention for achieving the above object is a SAR image forming simulation method for processing a raw image signal for a distributed target from a satellite, comprising: (a) an operation for obtaining an image of a SAR An operation mode setting step of setting a mode; (b) a satellite error setting step of defining an error range for the position and attitude of the satellite; (c) calculating a position of the satellite and a position of the target for each simulation time by inputting an observation time; (d) calculating a round trip distance (R array) of the satellite and the target during an imaging time, and calculating a phase delay for each pulse; (e) calculating a shadow area not reflected by each pulse, and calculating a diffusion value of the reflectivity map reflected by each pulse; And (f) calculating overlapping values of the I channel and the Q channel received in each pulse.

In addition, the step (a) sets the operation mode (Strip, Spotlight, Scan) for the SAR image acquisition.

In addition, the step (b) defines the error range for the antenna pointing position of the satellite and sets the error for the phenomenon that the satellite moves due to an external force such as satellite phase shift jitter and solar wind.

In addition, step (c) sets the shooting time of the satellite to UTC time.

In addition, step (d) calculates the arrival time of the forward path and the arrival of the backward path to the satellite.

Further, step (e) calculates the local projection angle between the signal and the indicator.

In the step (e), the continuously varying indicator model is modeled as a Facet type using Piecewise Planar Approximation to calculate a local projection angle between the signal and the indicator.

In addition, the slope of each resolution cell of the DEM is calculated to model in the facet shape, and the slope is defined as a vector parallel to the facet, and is represented by the sum of the gradient component, which is an inclination angle, and the aspect component, which is an azimuth angle.

In the step (d), an antenna gain value to be applied for each pulse is calculated, and the values of the I channel and the Q channel received in each pulse are overlapped and calculated.

According to the present invention, it is possible to implement a model that most appropriately expresses the state of the earth's surface and predicts microwave scattering characteristics in this state.

In the range direction, Chirp Pulps generation modeling can be implemented by simulating wideband pulse generation and compression techniques including amplitude / phase stability and rate of change of LFM pulses.

In addition, the spotlight mode can be used to form a high resolution image to improve resolution in the azimuth direction.

In addition, we analyze the effects of SAR satellite system design parameters on the final image to improve SAR satellite system design capability, and simulate and analyze various parameters to simulate and predict the final image quality of the designed satellite and sensor. Can be implemented.

1 is a configuration diagram schematically showing the configuration of a SAR image forming simulation system according to an embodiment of the present invention.
2 is a flowchart illustrating a process of processing a raw image signal for a point target / multi target in a SAR image forming simulation method according to an exemplary embodiment of the present invention.
3 is a diagram illustrating a point target raw video signal generated according to an embodiment of the present invention.
4 is a flowchart illustrating a process of processing a raw image signal for a dispersion target in a SAR image forming simulation method according to an exemplary embodiment of the present invention.
5 is a view showing a FACET model according to an embodiment of the present invention.
6 is a view showing a shadow model according to an embodiment of the present invention.
7 is a view showing a Kirchhoff diffusion model according to an embodiment of the present invention.
8 is a diagram illustrating a multi-target raw signal image according to an embodiment of the present invention.
9 is a view illustrating a processed image of a distributed target raw signal according to an embodiment of the present invention.
10 illustrates quantitative quality of a SAR image according to an embodiment of the present invention.
FIG. 11 is a diagram illustrating a quantitative change in quality of SAR images due to satellite error according to an embodiment of the present invention. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a configuration diagram schematically showing the configuration of a SAR image forming simulation system according to an embodiment of the present invention.

Referring to FIG. 1, the SAR image forming simulation system 100 according to the present invention includes a project package unit 110, an orbit package unit 120, a SAR hardware package unit 130, and a target package unit 140. ), A simulation package unit 150, a display package unit 160, and an operation selector 170.

The satellite error setting unit may further define an error range for the antenna pointing position of the satellite and set an error for a satellite shift due to an external force such as satellite phase shift jitter and solar wind. It may include.

The project package unit 110 generates or manages a simulation scenario of SAR for image acquisition from a satellite.

The orbit package 120 designs satellite orbits from Kepler orbital elements for satellites and predicts orbital elements at arbitrary times.

The SAR hardware package unit 130 calculates an index range affected by the antenna using the antenna parameters of the SAR, and models the received signal to reflect the influence of the antenna performance and the error factor.

When simulating the received signal of the SAR, the target package unit 140 generates a reflectivity map using virtual ground clutter information.

The simulation package 150 generates and processes a simulated signal using the orbital element, the payload information, and the clutter information about the satellite to execute a simulation according to an operation mode.

The display package unit 160 forms a final SSAR image from the simulation signal according to the simulation, performs geometric / radial quality evaluation on the formed image, and displays or stores the result on the screen.

The operation selector 170 selects whether to operate in a strip mode, a scan mode, or a spotlight mode for an operation mode for acquiring an image of a SAR. .

In FIG. 1, the simulation package 150 includes an operation mode setting process, a satellite error setting process, an orbit propagation process, a propagation pulse delay process, and a calculated return signal process. A point target or a multi-target raw signal is generated by using the target signal.

In this case, the operation mode setting process selects whether to operate in a strip mode, a scan mode, or a spotlight mode for an operation mode for acquiring an image of a SAR. Set the satellite operating mode to

In addition, the satellite error setting process defines an error range for the antenna pointing position of the satellite and sets an error for a phenomenon in which the satellite moves due to an external force such as satellite phase shift jitter and solar wind.

In addition, the orbit propagation process sets the imaging time of the satellite, inputs the observation time of the SAR, and calculates the position of the satellite and the position of the target for each simulation time.

In addition, the propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, and the round trip distance between the satellite and the target during the imaging time. Calculate the (R array) and calculate the phase delay for each pulse.

In addition, the return signal calculation process calculates an antenna gain value to be applied to each pulse, a window filter value to be applied to each pulse, and calculates values of I and Q channels received in each pulse. do.

Meanwhile, the simulation package 150 includes an orbit propagation process, a propagation pulse delay process, a reflection map display process, and a superposition return signal calculation. To generate a distributed target raw signal.

At this time, the orbit propagation process sets the shooting time of the satellite, inputs the observation time of the SAR, and calculates the position of the satellite and the target for each simulation time.

In addition, the propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, and the round trip distance between the satellite and the target during the imaging time. Calculate the (R array) and calculate the phase delay for each pulse.

In addition, the reflectivity map display process calculates a local incidence angle between the signal and the indicator, calculates shadow areas that are not reflected in each pulse, and diffuses the reflectivity map reflected in each pulse. Calculate the Scattering value.

In addition, the overlap return signal calculation process calculates an antenna gain value to be applied to each pulse, calculates a window filter value to be applied to each pulse, and calculates values of I and Q channels received in each pulse. Calculate by overlapping.

2 is a flowchart illustrating a process of processing a raw image signal for a point target / multi target in a SAR image forming simulation method according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the SAR image forming simulation system 100 according to the present invention is an orbit propagation process, and sets a time when the position of the satellite is closest to the target along the trajectory of the satellite to zero time. In addition, the position of the satellite and the position of the target are calculated for each simulation time by inputting the observation time of the SAR in the payload module (S210).

Subsequently, the SAR image forming simulation system 100 calculates the arrival time of the forward path and the backward path of the satellite as a propagation delay process, and calculates the imaging time. It calculates the round trip distance (R array) of the satellite and the target during (Imaging Time), and calculates a phase delay for each pulse (S220).

Subsequently, the SAR image forming simulation system 100 calculates an antenna gain value and a window filter value to be applied to each pulse as a return signal generation process, and receives each pulse. The calculated values of the I channel and the Q channel are calculated (S230).

In addition, the SAR image forming simulation system 100 forms a point target raw signal based on the system parameters calculated as described above through the simulation package unit 150 to display the display unit 160 as shown in FIG. 3. Display through (S240).

3 is a diagram illustrating a point target raw video signal generated according to an embodiment of the present invention. As shown in FIG. 3, in the point target raw video signal, phase signals are uniformly distributed, and a phase delay is generated in the center of the raw video signal.

4 is a flowchart illustrating a process of processing a raw image signal for a multi-target in a SAR image forming simulation method according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the SAR image forming simulation system 100 according to the present invention sets the shooting time of the satellite to UTC time and inputs the observation time (tx time of a pulse) of the SAR in the payload module for each simulation time. A satellite position (Vs0: satellite position) and a target position (Vt0: target position) are calculated (S410).

Subsequently, the SAR image forming simulation system 100 calculates the forward time (t1: forward path) of the forward path and the backward path (t2: backward path) of the satellite, and during the imaging time (Imaging Time) The satellite and the round trip distance (R array Delay) of the target is calculated, and the phase delay (Phase delay) for each pulse (S420).

Subsequently, the SAR image forming simulation system 100 calculates a local incidence angle between the signal and the indicator, calculates shadow areas not reflected by each pulse, and reflectance maps reflected by each pulse. Scattering value of is calculated (S430).

In this case, in order to obtain a local incidence angle between a signal and an index, the SAR image forming simulation system 100 first needs to calculate a direction of direction of each index point as shown in FIG. 5. The surface model is modeled as a facet using Piecewise Planar Approximation. 5 is a view showing a FACET model according to an embodiment of the present invention.

In addition, the slope of each resolution cell of the digital elevation model (DEM) is calculated to model in the facet shape, and the slope is defined as a vector parallel to the facet, and is expressed as the sum of the gradient component and the azimuth aspect component.

Subsequently, the SAR image forming simulation system 100 calculates the shadow and layover of the projection surface by using the azimuth and elevation angles of the satellite. At this time, Z-buffer algorithm is used. The Z-buffer algorithm is mainly used in the field of computer graphics for visibility analysis. In 1998, Amhar applied it to the detection of shadow area when producing aerial images of aerial photographs. Algorithms related to occlusion detection have been suggested at home and abroad, but the occlusion detection method using the Z-buffer algorithm is most widely used.

As shown in FIG. 6, the SAR image forming simulation system 100 according to the present invention has a center position (X, Y, Z) and attitude information (w, k, f) of SAR for visual analysis using a Z-buffer algorithm. ), DEM is required. The shadow area is detected by comparing the distance from the center of SAR to the DEM. 6 is a view showing a shadow model according to an embodiment of the present invention.

At this time, the application method of the algorithm generates a virtual grid having the same coordinate system and size as the DEM (distance image). After the distance between all points of the target space (DEM) is obtained from the center position of the SAR, the distance is stored in corresponding coordinates of the generated distance image. Gradient projection conversion is performed on the DEM by using the posture information (w, k, f) and the center position (X, Y, Z) of the camera at the time of image acquisition. Instead of the height value, the distance value stored in the distance image is assigned by referring to the coordinate value of the original DEM. The shadow area can be determined by comparing the distance to be stored in the Z-buffer.

In FIG. 6, the points A and F are not shadow regions, and have one coordinate on the Z-buffer at the gradient projection conversion. However, in the case of points B and D, it is a shadow area, and when transformed, they have the same coordinates (positioned on the same collimation line) on points C, E, and Z-buffer, not the shadow area. Therefore, B'B <B'C is the distance from the DSM calculated above to the average sea level, because point C is closer to the satellite and point B is farther from the satellite. Therefore, point B corresponds to the occlusion area. Similarly, D'D, D'E could be compared to determine the shadow area except the largest value, and null is given to the detected area to show the result.

In addition, the SAR image forming simulation system 100 according to the present invention uses a scattering model as shown in FIG. 7. FIG. 7 is a view showing a Kirchhoff Scattering Model according to an embodiment of the present invention. FIG.

As shown in FIG. 7, the diffusion model reflects surface characteristics to Surface Roughness or Moisture Content, and includes polarization information, radar frequency information, and projection angle. Incidence angle information, local slope information, surface roughness information, moisture content information, etc. are input to the scattering model, and the reflection map is reflected by reflecting the DEM information. It is created and displayed on the screen.

Subsequently, the SAR image forming simulation system 100 calculates an antenna gain value to be applied to each pulse, calculates a window filter value to be applied to each pulse, and calculates the I and Q channels received from each pulse. The return signal is generated by overlapping the calculated values (S440).

The SAR used in the SAR image forming simulation system 100 according to the present invention is an advanced radar technique for obtaining a high resolution image image of a target using microwaves in a microwave band. As shown in FIG. 8, a high resolution video image is obtained through focused SAR signal processing that changes a phase of a received signal. That is, SAR generates SAR focusing image by applying CSA (Chirp Scaling Algorithm) algorithm in Strip Map Mode, applies Frequency Scaling Algorithm (FSA) algorithm in Spotlight Mode, and SPECtral ANalysis method in Scan Mode. ) Generate SAR Focusing image by applying algorithm.

8 is a diagram illustrating a multi-target raw signal image according to an embodiment of the present invention. As shown in FIG. 8, an image compressed in a distance direction with respect to the raw signal image may be acquired, and an image compressed in the flight direction may be obtained.

9 is a view illustrating a processed image of a distributed target raw signal according to an embodiment of the present invention. In FIG. 9, (a) shows digital elevation model (DEM) information for modeling the facet of FIG. 5, and (b) shows a distance by generating a raw signal image from a reflection map from which a slope of each resolution cell is calculated. It shows the result of the image compressed in the direction (Range Compressed) and in the direction of flight (Azimuth Compressed).

Here, the SAR image displayed on the screen through the display package unit 160 in the SAR image forming simulation system 100 according to the present invention may be stored in the form of SLC (Single Look Complex) data. Most SLC data is stored in the form of band interleaved by pixel (BIP), band interleaved by line (BIL), and band sequential (BSQ). The same data format is used when processing data in a program. Receives data from SAR-equipped satellites and fish, and stores observation data in two channels: I (In Phase) and Q (Quadrature Phase). Since both channels form one sample of data, the BIP format is convenient for handling the data.

In addition, the SAR image forming simulation system 100 according to the present invention is a PSLR (resolution of the image in azimuth, and range) as a unit defined for measuring Radiometric Quality of a SAR image as a quantitative quality measure for measuring a quality of a SAR image. ) And ISLR (equivalent looks in azimuth, and range).

Accordingly, when comparing the quantitative quality, as shown in FIG. 10, the higher the PSLR value, the better the image quality. 10 illustrates quantitative quality of a SAR image according to an embodiment of the present invention.

In FIG. 10, (a) shows an over sampled image according to a range and azimuth, (b) shows a magnitude of range according to a distance, and (c) Magnitude of Azimuth is shown by flight, and (d) shows a quality measure result.

FIG. 11 is a diagram illustrating a quantitative quality variation of a SAR image due to an error of a satellite according to an embodiment of the present invention. FIG.

In FIG. 11A, Bus Pointing Error defines an error range for a satellite's pointing position, and Payload Pointing Error defines a range of mechanical steering angle and electrical steering angle errors of the SAR payload. Satellite Stability is a satellite phase shift error, and jitters show vibrations caused by satellite disturbances. Drift is a phenomenon in which satellites are moved by external forces such as solar wind. (b) shows the decrease in quality when there is no satellite error and all errors are reflected.

As described above, according to the present invention, by setting the shooting time of the satellite, calculate the time when the position is closest to the target, input the observation time of SAR, calculate the position of the satellite and the position of the target for each simulation time, SAR images can be formed based on system parameters such as the satellite's forward and backward paths, phase delay time for each pulse, antenna gain value, window filter value, and I and Q channel values received in each pulse. SAR image forming simulation system and method can be realized.

As those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features, the embodiments described above are intended to be illustrative in all respects and should not be considered as limiting. Should be. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

The present invention can be applied to an image radar device that generates an image such as taking a photograph by a camera by detecting a target on the ground using electromagnetic waves.

In addition, performance verification of SAR system can be applied by analyzing the effects of SAR satellite mission planning and satellite position, attitude, and pointing error.

In addition, the scattering characteristics of the object displayed on the image radar can be modeled and applied to an algorithm for extracting physical factors.

In addition, a simulation system for forming SAR image data and a large amount of data must be processed at high speed to be applied to an image radar device or system.

100: SAR image formation simulation system 110: Project package part
120: track package portion 130: SAR hardware package portion
140: target package unit 150: simulation package unit
160: display package unit 170: operation selection unit

Claims (25)

A project package unit for generating or managing a simulation scenario of SAR for image acquisition from a satellite;
An orbit package unit for designing satellite orbits from Kepler orbital elements for the satellites and predicting orbital elements at arbitrary times;
A SAR hardware package unit configured to calculate an index range affected by the antenna using the antenna parameters of the SAR, and model the received signal to reflect the influence of the antenna performance and error factors;
A target package unit configured to generate a reflection map using virtual terrestrial clutter information when simulating the received signal of the SAR;
A simulation package unit configured to generate and process a simulated signal using the orbital element, the payload information, and the clutter information for the satellite to execute a simulation according to an operation mode; And
A display package unit for forming a final SAR image from the simulation signal according to the simulation, performing geometric / radial quality evaluation on the formed image, and displaying or storing the result on a screen;
SAR image formation simulation system comprising a.
The method of claim 1,
An operation selection unit for selecting whether to operate in a strip mode, a scan mode, or a spotlight mode with respect to an operation mode for acquiring an image of the SAR;
SAR image forming simulation system, characterized in that it further comprises.
The method of claim 1,
A satellite error setting unit that defines an error range for the antenna pointing position of the satellite and sets an error of a satellite shift due to an external force such as a phase shift jitter and a solar wind of the satellite;
SAR image forming simulation system, characterized in that it further comprises.
The method of claim 1,
The simulation package unit generates a raw signal of a point target or a multi target through an operation mode setting process, a satellite error setting process, an orbit propagation process, a propagation pulse delay process, and a return signal calculation process. SAR image forming simulation system, characterized in that.
The method of claim 4, wherein
The operation mode setting process may select whether to operate in a strip mode, a scan mode, or a spotlight mode for an operation mode for acquiring an image of the SAR. SAR image forming simulation system, characterized in that for setting the satellite operating mode for.
The method of claim 4, wherein
The satellite error setting process is to define the error range for the antenna pointing position of the satellite, and to set the error for the drift of the satellite by the external force including the phase shift jitter and the solar wind of the satellite. A SAR image forming simulation system.
The method of claim 4, wherein
The orbit propagation process is a SAR image forming simulation system, characterized in that for calculating the position of the satellite and the position of the target for each simulation time by inputting the observation time of the SAR.
The method of claim 4, wherein
The propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, calculates the round trip distance of the satellite and the target during the imaging time, and calculates the phase delay for each pulse. SAR image forming simulation system, characterized in that.
The method of claim 4, wherein
The return signal calculation process may include calculating an antenna gain value to be applied to each pulse and calculating a value of an I channel and a Q channel received in each pulse.
The method of claim 1,
The simulation package unit, the SAR image forming simulation system, characterized in that for generating a distributed target raw signal through the orbit propagation process, propagation pulse delay process, reflectivity map display process and superposition return signal calculation process.
The method of claim 10,
The orbit propagation process is a SAR image forming simulation system, characterized in that for calculating the position of the satellite and the position of the target for each simulation time by inputting the observation time of the SAR.
The method of claim 10,
The propagation pulse delay process calculates the arrival time of the forward path, calculates the arrival time of the backward path, calculates the round trip distance of the satellite and the target during the imaging time, and calculates the phase delay for each pulse. SAR image forming simulation system, characterized in that.
The method of claim 10,
The reflectivity map display process includes calculating a local projection angle between a signal and an indicator, calculating a shadow area not reflected by each pulse, and calculating a spread value of the reflectivity map reflected by each pulse. Image Formation Simulation System.
The method of claim 10,
In the superimposition return signal calculation process, an antenna gain value to be applied to each pulse is calculated, and the SAR image forming simulation system of claim 1, wherein the I channel and Q channel values received in each pulse are overlapped and calculated.
A SAR image formation simulation method for processing a raw image signal for a point target / multi target from a satellite,
(a) an operation mode setting step of setting an operation mode for obtaining an image of a SAR;
(b) a satellite error setting step of defining an error range for an antenna pointing position of a satellite and setting an error of a satellite shift due to an external force including a satellite phase shift jitter and solar wind;
(c) an orbit propagation step of calculating a position of the satellite and a position of the target by setting a time when the position of the satellite is closest to the target along the orbit of the satellite and inputting an observation time;
(d) a propagation delay that calculates the arrival time of the forward path and the backward path to the satellite, calculates the round trip distance of the satellite and the target during the imaging time, and calculates a phase delay for each pulse; step; And
(e) a return signal calculating step of calculating an antenna gain value and a window filter value to be applied to each pulse, and calculating values of I and Q channels received in each pulse;
Image forming simulation method of SAR comprising a.
The method of claim 15,
The point target / multi-target raw video signal generated after step (e) has a phase signal uniformly distributed, and a phase delay is generated in the center of the raw video signal. .
A SAR image formation simulation method for processing raw image signals from satellites to a distributed target,
(a) an operation mode setting step of setting an operation mode for obtaining an image of a SAR;
(b) a satellite error setting step of defining an error range for the position and attitude of the satellite;
(c) calculating a position of the satellite and a position of the target for each simulation time by inputting an observation time;
(d) calculating a round trip distance (R array) of the satellite and the target during an imaging time, and calculating a phase delay for each pulse;
(e) calculating a shadow area not reflected by each pulse, and calculating a diffusion value of the reflectivity map reflected by each pulse; And
(f) calculating overlapping values of the I channel and the Q channel received in each pulse;
Image forming simulation method of SAR comprising a.
The method of claim 17,
The step (a) is the image forming simulation method of the SAR, characterized in that for setting the operation mode (Strip, Spotlight, Scan) for the SAR image acquisition.
The method of claim 17,
Step (b) is to define the error range for the antenna pointing position of the satellite, and to set the error for the phenomenon (drift) of the satellite moving due to the satellite phase shift error (jitter) and the external force such as solar wind Image formation simulation method of SAR.
The method of claim 17,
In the step (c), the image forming simulation method of the SAR, characterized in that for setting the shooting time of the satellite to UTC time.
The method of claim 17,
In step (d), the arrival time of the forward path to the satellite and the arrival time of the backward path are calculated.
The method of claim 17,
And (e) calculating a local projection angle between the signal and the indicator.
The method of claim 17,
In the step (e), the image modeling simulation method of SAR, characterized by modeling the continuously changing surface model in the facet form using Piecewise Planar Approximation to calculate the local projection angle between the signal and the surface.
The method of claim 17,
Slope of each resolution cell of the DEM is calculated to model in the facet shape, wherein the slope is defined as a vector parallel to the facet and is represented by the sum of the gradient component, the inclination angle, and the azimuth aspect component. Way.
The method of claim 17,
In step (d), an antenna gain value to be applied to each pulse is calculated, and the image formation simulation method of SAR, wherein the values of the I channel and the Q channel received in each pulse are calculated by overlapping.

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