Method and system for analyzing factors influencing deformation measurement accuracy of differential interferometric SAR satellite

Abstract

The application provides a differential interferometric SAR satellite deformation variable measurement precision influence factor analysis method and system, comprising: obtaining error sources affecting system positioning precision; deriving an error transfer function of differential interferometric SAR satellite ground surface deformation variable measurement according to the error sources; setting satellite system parameters according to deformation variable measurement requirements; calculating the influence degree of error sources on differential interferometric SAR deformation variable measurement precision through the satellite system parameters and the error transfer function; and performing deformation variable measurement precision solidification calculation and responding to changes in satellite parameters. The application can be used for differential interferometric SAR deformation variable measurement satellite system overall design, solves the differential interferometric SAR deformation variable measurement precision change problem caused by changes in satellite system design parameters, and can quickly respond to the influence of changes in satellite design parameters on differential interferometric SAR deformation variable measurement precision.

Description

Technical Field

[0001] This invention relates to the field of signal and information processing technology, specifically to a method and system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement. Background Technology

[0002] Differential Interferometric Synthetic Aperture Radar (DISAR) is an important remote sensing tool for acquiring information about surface deformation, playing a crucial role in monitoring geophysical phenomena such as seismic deformation, landslides, and ground subsidence. In DISAR deformation measurement, a SAR satellite passes over the same area twice, observing surface deformation during these two passes. This yields two SAR images of the area, one before and one after the deformation. Under certain conditions regarding the satellite's reorbiting time and inter-satellite baseline, interferometry is applied to the two acquired SAR images to obtain interferometric phase information. The phase of any pixel in the interferogram represents the sum of the change in distance between the radar and that pixel and the change in the target's scattering phase. If the scattering phase remains stable between the two observations, the interferometric phase reflects the change in distance between the target and the radar during the two observations, including topographic information, surface deformation, and phase delay caused by atmospheric activity. The topographic phase is determined using known DEM (Digital Elevation Model) data of the observation area. The phase delay caused by the atmosphere and ionosphere is calculated through atmospheric compensation and removed from the interferometric phase. The remaining deformation phase is then used to invert the surface deformation.

[0003] The accuracy of deformation measurement in differential interferometric SAR (DISAR) satellites is a core indicator of the satellite system, directly impacting the application value of deformation products. Therefore, analyzing the factors influencing the accuracy of DISAR satellite deformation measurement is a crucial task in DISAR satellite system design. On one hand, satellite system designers need to analyze these influencing factors to identify and allocate various engineering performance requirements. On the other hand, designers also need to perform calculations and analyses on the actual engineering development results to evaluate the on-orbit deformation measurement performance of the DISAR satellite. The analysis of factors influencing the accuracy of DISAR satellite deformation measurement involves integrated satellite and ground design, system decoherence, baseline measurement errors, satellite position and velocity errors, slant range measurement errors, and many other factors. It also requires in-depth analysis of the sensitivity to deformation measurement accuracy errors and the establishment of a full-link error model for the DISAR satellite.

[0004] Patent document CN115453520A discloses a method and equipment for measuring surface deformation based on dual-frequency multi-polarization differential interferometry, which obtains multi-scale surface deformation information of different land cover types by fusing L-band and X-band measurements.

[0005] Patent document CN216411556U discloses a synthetic aperture radar system based on time-series interferometric deformation measurement for data preprocessing of SAR image sets; removing flat and terrain phases from the interferometric phase to generate differential interferometric phases, and calculating differential interferograms pixel by pixel; performing linear deformation phase estimation in the time and spatial domains on the differential interferometric phases to obtain the time-series deformation phase of each point target; and calculating phase transformation deformation based on radar wavelength parameters to obtain the deformation measurement value of the synthetic aperture radar image.

[0006] Patent document CN115372964A discloses a dual-frequency multi-scale surface deformation measurement test system, including two sets of X-band polarized antennas, two sets of L-band polarized antennas, two sets of X-band front-end receiving equipment, two sets of L-band front-end receiving equipment, two sets of transmitting equipment, two sets of calibration equipment, one integrated control unit, two sets of wave control units, two sets of servo mechanisms, two sets of inertial navigation equipment, and one set of recording equipment. The two sets of X-band polarized antennas transmit and receive X-band polarized signals, respectively placed on the left and right sides of the antenna frame to form an X-band cross-track interference baseline; the two sets of L-band polarized antennas transmit and receive L-band polarized signals, respectively placed on the left and right sides of the antenna frame to form an L-band cross-track interference baseline.

[0007] Patent document CN114624708A discloses an atmospheric correction method and system for complex environments, including: extracting permanent scatterer (PS) points from a time-series image data to obtain a PS point set; dividing the PS point set into regions, with all region center points forming a center point set S; triangulating the S to construct a triangular network; performing atmospheric phase interpolation on the PS point set based on the triangular network to obtain an atmospheric phase estimation result p'; and subtracting p' from the cumulative phase of the time-series image data to complete atmospheric correction.

[0008] Patent document CN108983232A discloses an InSAR two-dimensional surface deformation monitoring method based on adjacent orbit data. First, SAR data from adjacent orbits are used to obtain surface deformation measurements in two different slant range directions. Then, deformation measurements in two different slant range directions are obtained for the common area of ​​the adjacent orbits. Next, the incident angle and azimuth angle of each point in the common area are calculated for both orbits. Subsequently, a coefficient matrix is ​​constructed for each point. Finally, based on the rigorous geometric relationship between satellite imaging geometry and surface deformation, ignoring north-south deformation, a system of equations is established, and the two-dimensional surface deformation is obtained by solving the equations using the least squares criterion.

[0009] None of the methods proposed in the aforementioned patent documents provide a comprehensive and systematic error analysis and system design for deformation measurement accuracy based on the positioning principle. With the rapid development of spaceborne differential interferometric SAR technology, the application demands for deformation measurement products are increasing. Therefore, it is imperative to focus on researching methods that can analyze the influencing factors of differential interferometric SAR satellite deformation measurement accuracy, ensuring better universality and faster response speed. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurements.

[0011] A method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to the present invention includes:

[0012] Step S1: Identify the error sources affecting the system's positioning accuracy;

[0013] Step S2: Derive the error transfer function of the differential interferometric SAR satellite for measuring surface deformation based on the error sources;

[0014] Step S3: Set the satellite system parameters according to the deformation measurement requirements;

[0015] Step S4: Calculate the degree of influence of the error source on the measurement accuracy of differential interferometric SAR deformation using the satellite system parameters and the error transfer function;

[0016] Step S5: Perform deformation measurement accuracy calculations to respond to changes in satellite parameters.

[0017] Preferably, the error source is obtained by establishing a differential interferometric SAR satellite surface deformation measurement equation;

[0018] The establishment of the differential interferometric SAR satellite surface deformation measurement equation includes: the differential interferometric SAR surface deformation measurement observation equation, as shown in the following equation:

[0019]

[0020]

[0021] Where, φ InSAR The interference phase is represented by Δr, and the surface deformation is represented by φ. topo Indicates the terrain phase, φ atm Indicates the atmospheric delay differential phase during transit, φ cor The phase of the decoherent noise is represented by λ, which represents the radar wavelength, and p is the phase of the radar. t p represents the target position vector. sThe vector represents the position of the phase center of the satellite antenna, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0022] Deformation measurement accuracy σ Δr As shown in the following formula:

[0023]

[0024] Where Δr represents the surface deformation, Indicates the accuracy of terrain phase. Indicates the accuracy of atmospheric phase measurements. Indicates the decoherent phase accuracy;

[0025] Differential interferometric SAR uses the range-Doppler equation and a ground elevation model for ground target localization, as shown in the following equation:

[0026]

[0027] In the formula, r1 represents the slant distance of the main image, v s f represents the velocity vector. dc R represents the imaging Doppler center. e Ω represents the Earth's radius, h represents the ground elevation, f represents the Earth's oblateness factor, and Ω represents the Earth's flattening factor. DEM Represents the external digital elevation model (DEM), p t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z (t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0028] The error sources affecting the system's positioning accuracy include satellite orbit positioning error, satellite velocity error, slant range measurement error, interferometric baseline error, and ground elevation error.

[0029] Preferably, the satellite system parameters include satellite orbital altitude, radar carrier frequency, and operating wavelet parameters.

[0030] Preferably, the transfer function for the influence of the satellite orbit positioning error on the accuracy of surface deformation measurement includes:

[0031] The transfer function of the influence of the main image satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0032]

[0033]

[0034]

[0035] Where Δr represents the surface deformation, λ represents the radar wavelength, and p t p represents the target position vector. s p represents the position vector of the satellite antenna phase center. t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z p represents the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system. s,x p s,y p s,z These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system; v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in a fixed Earth coordinate system; the subscript i represents the i-th axis component, r1 represents the slant distance of the main image, and R... e denoted by , where f represents the Earth's radius, f represents the Earth's oblateness factor, and h represents the ground elevation.

[0036] The transfer function of the influence of satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0037]

[0038] Where Δr represents the surface deformation, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0039] Preferably, the transfer function based on the influence of the satellite velocity error on the accuracy of surface deformation measurement includes:

[0040]

[0041] Where Δr represents the surface deformation, v represents the satellite velocity, the subscript i represents the i-th axis component, λ represents the radar wavelength, and p t p represents the target position vector. s The vector represents the position of the phase center of the satellite antenna, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0042]

[0043] Where the subscript i represents the i-th axis component, p t,x ,p t,y ,p t,z p represents the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system. s,x p s,y p s,z These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system, respectively, and r1 represents the slant distance of the main image.

[0044] Preferably, the transfer function of the influence of the slope distance measurement error on the accuracy of surface deformation measurement includes:

[0045]

[0046] Where Δr represents the surface deformation, r1 represents the slant range of the main image, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry;

[0047]

[0048] Among them, f dc Indicates the center of the imaging Doppler.

[0049] Preferably, the transfer function based on the influence of the ground elevation error on the accuracy of surface deformation measurement includes:

[0050]

[0051] Where Δr represents the surface deformation, h represents the ground elevation, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry;

[0052]

[0053] Among them, R e This represents the Earth's radius.

[0054] Preferably, the coherence coefficient needs to take into account the decoherence caused by interference, and the total coherence coefficient is expressed as follows:

[0055] γ=γ temp ·γ SNR ·γ amb ·γ ISLR ·γ B ·γ Doppler ·γ vol ·γ coregis ·γ jam

[0056] In the formula, γ is the total coherence coefficient, γ temp Indicates time decoherence, γ SNR Indicates signal-to-noise ratio (SNR) decoherence, γ amb Indicates fuzzy decorrelation, γ ISLR Indicates sidelobe decoherence, γ B Indicates baseline decoherence, γ Doppler Indicates Doppler decoherence, γ vol Indicates volume scattering decoherence, γ coregis Indicates registration decoherence, γ jam This indicates interference decoherence.

[0057] A system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to the present invention includes:

[0058] Module M1: Identify error sources affecting the system's positioning accuracy;

[0059] Module M2: Derive the error transfer function of differential interferometric SAR satellite for measuring surface deformation based on the error sources;

[0060] Module M3: Set satellite system parameters according to deformation measurement requirements;

[0061] Module M4: Calculates the degree of influence of the error source on the measurement accuracy of differential interferometric SAR deformation using the satellite system parameters and the error transfer function;

[0062] Module M5: Performs calculations to solidify the accuracy of deformation measurement and responds to changes in satellite parameters.

[0063] Preferably, the error source is obtained by establishing a differential interferometric SAR satellite surface deformation measurement equation;

[0064] The establishment of the differential interferometric SAR satellite surface deformation measurement equation includes: the differential interferometric SAR surface deformation measurement observation equation, as shown in the following equation:

[0065]

[0066]

[0067] Where, φ InSAR φ represents the interference phase, Δr represents the surface deformation, and φ represents the surface deformation. topo Indicates the terrain phase, φ atm Indicates the atmospheric delay differential phase during transit, φ cor The phase of the decoherent noise is represented by λ, which represents the radar wavelength, and p is the phase of the radar. t p represents the target position vector. s The vector represents the position of the phase center of the satellite antenna, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0068] Deformation measurement accuracy σ Δr As shown in the following formula:

[0069]

[0070] Where Δr represents the surface deformation, Indicates the accuracy of atmospheric phase measurements. Indicates the decoherent phase accuracy. Indicates the decoherent phase accuracy;

[0071] Differential interferometric SAR uses the range-Doppler equation and a ground elevation model for ground target localization, as shown in the following equation:

[0072]

[0073] In the formula, r1 represents the slant distance of the main image, v s f represents the velocity vector. dc R represents the imaging Doppler center. e Ω represents the Earth's radius, h represents the ground elevation, f represents the Earth's oblateness factor, and Ω represents the Earth's flattening factor. DEM Represents the external digital elevation model (DEM), p t =(p t,x ,p t,y ,p t,z ) T The superscript "T" indicates matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z(t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0074] The error sources affecting the system's positioning accuracy include satellite orbit positioning error, satellite velocity error, slant range measurement error, interferometric baseline error, and ground elevation error.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] 1. The processing approach of this invention differs from existing design methods. It is the first to propose a method for analyzing the factors affecting the measurement accuracy of differential interferometric SAR deformation based on the differential interferometric SAR positioning equation.

[0077] 2. This invention is based on a rigorous theoretical model for calculation and solidifies the calculation process. Compared with existing technologies, it provides a more comprehensive analysis of error items and solves the problem of changes in the measurement accuracy of differential interferometric SAR deformation caused by changes in satellite system design parameters. It can quickly respond to the impact of changes in satellite design parameters on the measurement accuracy of differential interferometric SAR deformation. Attached Figure Description

[0078] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0079] Figure 1 This is a schematic diagram of the processing flow of the working method of the present invention.

[0080] Figure 2 This is a schematic diagram of the geometry of differential interferometric SAR observation.

[0081] Figure 3 A schematic diagram illustrating the effect of the main image satellite orbit determination error (0.01m) on the differential interferometric phase of the double orbit.

[0082] Figure 4 A schematic diagram illustrating the effect of satellite orbit determination error (0.01m) on the phase of the differential interferometric test for double orbit.

[0083] Figure 5 A schematic diagram illustrating the effect of the main image satellite velocity measurement error (0.001 m / s) on the phase of the differential interferometry in the double orbit.

[0084] Figure 6 This is a schematic diagram illustrating the effect of systematic slant range error on the phase of the differential interference of the double-track system.

[0085] Figure 7 This is a schematic diagram showing the effect of ground elevation error (5m) on the differential interference phase of the heavy rail.

[0086] Figure 8 The curve (16 views) shows the variation of interferometric phase accuracy with coherence coefficient.

[0087] Figure 9 The curve shows the change in deformation measurement accuracy as a function of interference phase error. Detailed Implementation

[0088] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0089] According to the present invention, a method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement is provided, such as... Figure 1 The above includes:

[0090] Step S1: Identify the error sources affecting the system's positioning accuracy. This includes obtaining the error sources by establishing the differential interferometric SAR satellite surface shape measurement equation. Establishing the differential interferometric SAR satellite surface shape measurement equation includes: the differential interferometric SAR surface shape measurement observation equation. Specifically, in heavy-orbit differential interferometry, the radar slant range information contained in the phase of the target point in the SAR image is directly obtained through time delay measurement, or obtained after interferometric processing of two SAR images, as shown in the following equation:

[0091]

[0092] In the formula, λ is the radar wavelength, and φ is the absolute interferometric phase obtained by interferometric processing of the SAR images acquired from Flight 1 and Flight 2. r2 can be obtained by acquiring the spatial position of the target before deformation using the known external DEM, r1, and Doppler equations. The final deformation of the target in the radar line-of-sight direction before and after deformation is as follows:

[0093] Δr=r2-r′2

[0094] In practical differential interferometric SAR, the interferometric phase includes not only the deformation phase and terrain phase, but also the atmospheric delay differential phase between two passes and the decoherent phase noise. As shown in the following equation:

[0095]

[0096]

[0097] Where, φ InSAR The interference phase is represented by Δr, and the surface deformation is represented by φ.topo Indicates the terrain phase, φ atm Indicates the atmospheric delay differential phase during transit, φ cor The phase of the decoherent noise is represented by λ, which represents the radar wavelength, and p is the phase of the radar. t p represents the target position vector. s t1 represents the position vector of the phase center of the satellite antenna, and t2 represents the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0098] Deformation measurement accuracy σ Δr As shown in the following formula:

[0099]

[0100] Where Δr represents the surface deformation, Indicates the accuracy of terrain phase. Indicates the accuracy of atmospheric phase measurements. This indicates the decoherence phase accuracy.

[0101] Differential interferometric SAR uses the range-Doppler equation and a ground elevation model for ground target localization, as shown in the following equation:

[0102]

[0103] In the formula, r1 represents the slant distance of the main image, v s f represents the velocity vector. dc R represents the imaging Doppler center. e Ω represents the Earth's radius, h represents the ground elevation, f represents the Earth's oblateness factor, and Ω represents the Earth's flattening factor. DEM Represents the external digital elevation model (DEM), p t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z (t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0104] Error sources affecting the positioning accuracy of the system include satellite orbit positioning error, satellite velocity error, slant range measurement error, interferometric baseline error, and ground elevation error.

[0105] Step S2: Derive the error transfer function for differential interferometric SAR satellite measurements of surface deformation based on the error sources. The transfer function, based on the influence of satellite orbit positioning error on the accuracy of surface deformation measurements, includes:

[0106] The transfer function of the influence of the main image satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0107]

[0108]

[0109]

[0110] Where Δr represents the surface deformation, λ represents the radar wavelength, and p t p represents the target position vector. s This represents the satellite antenna phase center position vector, where the subscript i represents the i-th axis component, r1 represents the slant range of the main image, and R e Let h represent the Earth's radius, f represent the Earth's elevation, and p represent the Earth's oblateness factor. t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z (t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0111] The transfer function of the influence of satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0112]

[0113] Where Δr represents the surface deformation, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0114] The transfer function of the influence of satellite velocity error in the main image on the accuracy of surface deformation measurement includes:

[0115]

[0116] Where Δr represents the surface deformation, v represents the satellite velocity, the subscript i represents the i-th axis component, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the phase center of the satellite antenna, and t2 represents the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0117]

[0118] Where the subscript i represents the i-th axis component, p t,x ,p t,y ,p t,z p represents the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system. s,x p s,y p s,z These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system, respectively, and r1 represents the slant distance of the main image.

[0119] The transfer function of the influence of the main image slant distance measurement error on the accuracy of surface deformation measurement includes:

[0120]

[0121] Where Δr represents the surface deformation, r1 represents the slant range of the main image, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry.

[0122]

[0123] Among them, f dc r1 represents the Doppler imaging center and r1 represents the slant distance of the main image.

[0124] The transfer function of the influence of ground elevation error on the accuracy of surface deformation measurement includes:

[0125]

[0126] Where Δr represents the surface deformation, h represents the ground elevation, λ represents the radar wavelength, and p t p represents the target position vector. st1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry.

[0127]

[0128] Among them, R e This represents the Earth's radius.

[0129] The transfer function of the coherence coefficient to the decoherent noise phase is:

[0130]

[0131] In the formula, N l Let γ represent the number of views and γ be the total coherence coefficient. The total coherence coefficient is expressed as follows:

[0132] γ=γ temp ·γ SNR ·γ amb ·γ ISLR ·γ B ·γ Doppler ·γ vol ·γ coregis ·γ jam

[0133] In the formula, γ temp Indicates time decoherence, γ SNR Indicates signal-to-noise ratio (SNR) decoherence, γ amb Indicates fuzzy decorrelation, γ ISLR Indicates sidelobe decoherence, γ B Indicates baseline decoherence, γ Doppler Indicates Doppler decoherence, γ vol Indicates volume scattering decoherence, γ coregis Indicates registration decoherence, γ jam This indicates interference decoherence.

[0134] Step S3: Set the satellite system parameters according to the deformation measurement requirements. The satellite system parameters include satellite orbital altitude, radar carrier frequency, and operating wavefront parameters. See Table 1 below:

[0135] Table 1 Preliminary Design Results of Satellite System Parameters

[0136] orbital altitude 607km radar carrier frequency 1.26GHz range of incident angles 20°～46°

[0137] Step S4: Calculate the impact of the error source on the accuracy of differential interferometric SAR deformation measurement using satellite system parameters and the error transfer function. In other words, based on the set satellite parameters and the error transfer function of the error source for differential interferometric SAR satellite surface deformation measurement, calculate the impact of the error source on the accuracy of differential interferometric SAR deformation measurement. The influence of the main image satellite orbit determination error (0.01m each on all three axes) on the double-orbit differential interferometric phase is shown in the attached figure. Figure 3 As shown, the influence of the heading-direction orbit determination error on the heavy-track interferometric phase is negligible; the influences of radial and transheading orbit determination errors on the heavy-track differential interferometric phase vary slowly along the incident angle, with spatial variation less than 1.5° within a 100km range. It should be noted that differential interferometric SAR surface deformation measurement is a relative deformation measurement, and the slowly varying phase deviation can be corrected through fitting estimation.

[0138] The influence of auxiliary image satellite orbit determination error (0.01m each on all three axes) on the phase of the double orbit differential interferometry is shown in the attached figure. Figure 4 As shown, the influence of the heading-direction orbit determination error on the heavy-track interferometric phase is negligible; the influences of radial and transheading orbit determination errors on the heavy-track differential interferometric phase vary slowly along the incident angle, with spatial variation less than 1.5° within a 100km range. Differential interferometric SAR surface deformation measurement is a relative deformation measurement, and the slowly varying phase deviation can be corrected through fitting estimation.

[0139] The effect of satellite velocity measurement error (0.001 m / s on each of the three axes) on the phase of the double orbit differential interferometry is shown in the attached figure. Figure 5 As shown in the figure, the effect of velocity measurement error on the phase of interference of the heavy rails is negligible.

[0140] The effect of systematic slant distance error (3m) on the phase of the differential interferometry of the double track is shown in the attached figure. Figure 6 As shown in the figure, the systematic slant range error affects the phase of the differential interferometric SAR slowly along the incident angle, with a spatial variation of less than 2° within a 100km range. It should be noted that differential interferometric SAR surface deformation measurements are relative deformation measurements, and the slowly varying phase deviation can be corrected through fitting estimation.

[0141] The effect of elevation error (5m) on the phase of the differential interferometer of the double track is shown in the attached figure. Figure 7 As shown in the figure, the impact of elevation errors on the differential phase of the heavy rail varies under different effective vertical baselines. Ground elevation errors include elevation deviation and relative errors. This phase error not only introduces spatially varying errors but also random errors, requiring strict control.

[0142] The effect of coherence coefficient on the phase of double-track differential interferometry is shown in the attached figure. Figure 8As shown in the figure, the accuracy of deformation measurement increases with the increase of the coherence coefficient. To ensure the accuracy of deformation measurement, a coherence coefficient better than 0.7 is required, corresponding to a surface deformation measurement accuracy of approximately 3.5 mm.

[0143] For spaceborne differential interferometric SAR systems, the two SAR images formed by repeated orbit observations are not acquired at the same time. The differences in atmospheric conditions (air pressure, temperature, water vapor, wind direction, etc.) and ionospheric conditions during the propagation of radar signals in the two observations will bring about atmospheric delay and ionospheric delay in the propagation process of electromagnetic wave signals, which in turn will produce additional atmospheric delay phase and ionospheric delay phase in the SAR interferometric results, thus affecting the acquisition of high-precision surface deformation information.

[0144] The system designed in this paper has a center frequency of 1.26 GHz and a signal bandwidth of 80 MHz. When the coherence between the main and auxiliary images is better than 0.8, the ionospheric error, after suppression, has an impact of less than 1 mm on the deformation measurement error (the ionospheric error has spatially slowly varying characteristics, and the multi-look number is assumed to be 10000). The atmospheric delay phase has spatially slowly varying and temporally rapidly varying characteristics. Atmospheric delay phase extraction is achieved through multi-time series SAR analysis, and the atmospheric delay accuracy can be controlled to below the millimeter level.

[0145] The overall impact of interferometric phase error on the accuracy of deformation measurement is as follows: Figure 9 As shown, when the total interferometric phase error is 90°, the measurement accuracy of the deformation using the two-track method is approximately 3 cm.

[0146] Step S5: Perform deformation measurement accuracy calculations to respond to changes in satellite parameters.

[0147] The present invention also provides a system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement. This system can be implemented by executing the process steps of the method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement. That is, those skilled in the art can understand the method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement as a preferred embodiment of the system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement.

[0148] A system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement, provided by the present invention, includes:

[0149] Module M1: Identifies error sources affecting system positioning accuracy. This includes obtaining error sources by establishing differential interferometric SAR satellite surface deformation measurement equations. Establishing the differential interferometric SAR satellite surface deformation measurement equations includes: the differential interferometric SAR surface deformation measurement observation equations, as shown below:

[0150]

[0151]

[0152] Where, φ InSAR φ represents the interference phase, Δr represents the surface deformation, and φ represents the surface deformation. topo Indicates the terrain phase, φ atm φ represents the atmospheric delay differential phase during transit. cor The phase of the decoherent noise is represented by λ, which represents the radar wavelength, and p is the phase of the radar. t p represents the target position vector. s t1 represents the position vector of the phase center of the satellite antenna, and t2 represents the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0153] Deformation measurement accuracy σ Δr As shown in the following formula:

[0154]

[0155] Where Δr represents the surface deformation, Indicates the accuracy of terrain phase. Indicates the accuracy of atmospheric phase measurements. This indicates the decoherence phase accuracy.

[0156] Differential interferometric SAR uses the range-Doppler equation and a ground elevation model for ground target localization, as shown in the following equation:

[0157]

[0158] In the formula, r1 represents the slant distance of the main image, v s f represents the velocity vector. dc R represents the imaging Doppler center. e Ω represents the Earth's radius, h represents the ground elevation, f represents the Earth's oblateness factor, and Ω represents the Earth's flattening factor. DEM Represents the external digital elevation model (DEM), p t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z(t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0159] Error sources affecting the positioning accuracy of the system include satellite orbit positioning error, satellite velocity error, slant range measurement error, interferometric baseline error, and ground elevation error.

[0160] Module M2: Derives the error transfer function for differential interferometric SAR satellite measurements of surface deformation based on error sources. The transfer function, based on the influence of satellite orbit positioning errors on the accuracy of surface deformation measurements, includes:

[0161] The transfer function of the influence of the main image satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0162]

[0163]

[0164]

[0165] Where Δr represents the surface deformation, λ represents the radar wavelength, and p t p represents the target position vector. s This represents the satellite antenna phase center position vector, where the subscript i represents the i-th axis component, r1 represents the slant range of the main image, and R e Let h represent the Earth's radius, f represent the Earth's elevation, and p represent the Earth's oblateness factor. t =(p t,x ,p t,y ,p t,z ) T The superscript T denotes matrix transpose, p t,x ,p t,y ,p t,z These represent the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system, respectively. s (t1)=(v x (t1),v y (t1),v z (t1)) is the velocity vector of the satellite at time t1, v x v y v z These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively.

[0166] The transfer function of the influence of satellite orbit positioning error on the accuracy of surface deformation measurement is:

[0167]

[0168] Where Δr represents the surface deformation, and t1 and t2 represent the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0169] The transfer function of the effect of the main image satellite velocity error on the accuracy of surface deformation measurement includes:

[0170]

[0171] Where Δr represents the surface deformation, v represents the satellite velocity, the subscript i represents the i-th axis component, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the phase center of the satellite antenna, and t2 represents the azimuth time of the first passing target under SAR imaging geometry and the azimuth time of the second passing target under SAR imaging geometry, respectively.

[0172]

[0173] Where the subscript i represents the i-th axis component, p t,x ,p t,y ,p t,z p represents the x-axis, y-axis, and z-axis coordinates of the target position in a fixed Earth coordinate system. s,x p s,y p s,z These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system, respectively, and r1 represents the slant distance of the main image.

[0174] The transfer function of the influence of slope distance measurement error on the accuracy of surface deformation measurement includes:

[0175]

[0176] Where Δr represents the surface deformation, r1 represents the slant range of the main image, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry.

[0177]

[0178] Among them, f dc r1 represents the Doppler imaging center and r1 represents the slant distance of the main image.

[0179] The transfer function of the influence of ground elevation error on the accuracy of surface deformation measurement includes:

[0180]

[0181] Where Δr represents the surface deformation, h represents the ground elevation, λ represents the radar wavelength, and p t p represents the target position vector. s t1 represents the position vector of the satellite antenna phase center, and t2 represents the azimuth time of the target during the second pass under SAR imaging geometry.

[0182]

[0183] Among them, R e denoted by , where h represents the Earth's radius and h represents the ground elevation.

[0184] The coherence coefficient needs to take into account the decoherence caused by interference. The total coherence coefficient is expressed as follows:

[0185] γ=γ temp ·γ SNR ·γ amb ·γ ISLR ·γ B ·γ Doppler ·γ vol ·γ coregis ·γ jam

[0186] In the formula, γ is the total coherence coefficient, γ temp Indicates time decoherence, γ SNR Indicates signal-to-noise ratio (SNR) decoherence, γ amb Indicates fuzzy decorrelation, γ ISLR Indicates sidelobe decoherence, γ B Indicates baseline decoherence, γ Doppler Indicates Doppler decoherence, γ vol Indicates volume scattering decoherence, γ coregis Indicates registration decoherence, γ jam This indicates interference decoherence.

[0187] Module M3: Sets satellite system parameters according to deformation measurement requirements. Satellite system parameters include satellite orbital altitude, radar carrier frequency, and operating wavefront parameters.

[0188] Module M4: Calculates the impact of error sources on the accuracy of differential interferometric SAR deformation measurements using satellite system parameters and error transfer functions.

[0189] Module M5: Performs calculations to solidify the accuracy of deformation measurement and responds to changes in satellite parameters.

[0190] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0191] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement, characterized in that, include: Step S1: Identify the error sources affecting the system's positioning accuracy; Step S2: Derive the error transfer function of the differential interferometric SAR satellite for measuring surface deformation based on the error sources; Step S3: Set the satellite system parameters according to the deformation measurement requirements; Step S4: Calculate the degree of influence of the error source on the measurement accuracy of differential interferometric SAR deformation using the satellite system parameters and the error transfer function; Step S5: Perform deformation measurement accuracy calculations to respond to changes in satellite parameters; This includes obtaining the error sources by establishing differential interferometric SAR satellite surface deformation measurement equations; The establishment of the differential interferometric SAR satellite surface deformation measurement equation includes: the differential interferometric SAR surface deformation measurement observation equation, as shown in the following equation: in, Indicates the interference phase. Represents surface deformation. Indicates terrain phase, Indicates the atmospheric delay differential phase during flight. Indicates the phase of decoherent noise. Indicates the radar wavelength. Represents the target position vector. This represents the position vector of the satellite antenna phase center. and These represent the azimuth and time of the target during the first and second passes under SAR imaging geometry, respectively. Deformation measurement accuracy As shown in the following formula: in, Represents surface deformation. Indicates the accuracy of terrain phase. Indicates the accuracy of atmospheric phase measurements. Indicates the decoherence phase accuracy; Differential interferometric SAR uses the range-Doppler equation and a ground elevation model for ground target localization, as shown in the following equation: In the formula, Indicates the slant distance of the main image. Represents the velocity vector. Indicates the center of the imaging Doppler. Represents the Earth's radius. Indicates ground elevation. Represents the Earth's oblateness factor. Represents the external digital elevation model (DEM). The superscript T indicates matrix transpose. These represent the x-axis, y-axis, and z-axis coordinates of the target location in a fixed Earth coordinate system, respectively. for The velocity vector of the satellite at any given moment. , , These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively. The error sources affecting the system's positioning accuracy include satellite orbit positioning error, satellite velocity error, slant range measurement error, interferometric baseline error, and ground elevation error; The transfer function of the influence of the satellite orbit positioning error on the accuracy of surface deformation measurement includes: The transfer function of the influence of the main image satellite orbit positioning error on the accuracy of surface deformation measurement is: in, Represents surface deformation. Indicates the radar wavelength. Represents the target position vector. This represents the position vector of the satellite antenna phase center, with the subscript i representing the i-th axis component. Indicates the slant distance of the main image. Represents the Earth's radius. Indicates ground elevation. Represents the Earth's oblateness factor. The superscript T indicates matrix transpose. These represent the x-axis, y-axis, and z-axis coordinates of the target location in a fixed Earth coordinate system, respectively. , , These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system, respectively. for The velocity vector of the satellite at any given moment. , , These represent the x-axis, y-axis, and z-axis coordinates of the satellite velocity in the Earth's fixed coordinate system, respectively. The transfer function of the influence of satellite orbit positioning error on the accuracy of surface deformation measurement is: in, Represents surface deformation. and These represent the azimuth and time of the target during the first and second passes under SAR imaging geometry, respectively. The transfer function of the influence of the ground elevation error on the accuracy of surface deformation measurement includes: in, Represents surface deformation. Indicates ground elevation. Indicates the radar wavelength. Represents the target position vector. This represents the position vector of the satellite antenna phase center. This indicates the azimuth time of the target during the second pass under SAR imaging geometry; in, This represents the Earth's radius.

2. The method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to claim 1, characterized in that, The satellite system parameters include satellite orbital altitude, radar carrier frequency, and operating wavelet parameters.

3. The method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to claim 1, characterized in that, The transfer function of the influence of the satellite velocity error on the accuracy of surface deformation measurement includes: in, Represents surface deformation. This represents the satellite velocity, with the subscript i indicating the i-th axis component. Indicates the radar wavelength. Represents the target position vector. This represents the position vector of the satellite antenna phase center. and These represent the azimuth and time of the target during the first and second passes under SAR imaging geometry, respectively. Where the subscript i represents the i-th axis component, These represent the x-axis, y-axis, and z-axis coordinates of the target location in a fixed Earth coordinate system, respectively. , , These represent the x-axis, y-axis, and z-axis coordinates of the satellite in the Earth's fixed coordinate system, respectively. This represents the slant distance of the main image.

4. The method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to claim 1, characterized in that, The transfer function of the influence of the slope distance measurement error on the accuracy of surface deformation measurement includes: in, Represents surface deformation. Indicates the slant distance of the main image. Indicates the radar wavelength. Represents the target position vector. This represents the position vector of the satellite antenna phase center. This indicates the azimuth time of the target during the second pass under SAR imaging geometry; in, Indicates the center of the imaging Doppler. This represents the slant distance of the main image.

5. The method for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement according to claim 1, characterized in that, The coherence coefficient needs to take into account the decoherence caused by interference. The total coherence coefficient is expressed as follows: In the formula, The total coherence coefficient, Indicates time-related coherence. This indicates the signal-to-noise ratio (SNR) decoherence. This indicates fuzzy decoherence. This indicates that the sidelobe has been decohered. Indicates baseline decoherence. This indicates that Doppler decoherence, This indicates volume scattering decoherence. This indicates registration decoherence. This indicates interference decoherence.

6. A system for analyzing factors affecting the accuracy of differential interferometric SAR satellite deformation measurement using the method described in any one of claims 1 to 5, characterized in that, include: Module M1: Identify error sources affecting the system's positioning accuracy; Module M2: Derive the error transfer function of differential interferometric SAR satellite for measuring surface deformation based on the error sources; Module M3: Set satellite system parameters according to deformation measurement requirements; Module M4: Calculates the degree of influence of the error source on the measurement accuracy of differential interferometric SAR deformation using the satellite system parameters and the error transfer function; Module M5: Performs fixed-precision calculations for deformation measurement and responds to changes in satellite parameters.

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