Space-based ultra-long baseline interference SAR system design method and device

Abstract

The invention provides a space-based ultra-long baseline interference SAR (Synthetic Aperture Radar) system design method and device, and belongs to the field of radar measurement, and the method comprises the following steps: for double-base interference, analyzing the relation among elevation precision, phase error and coherence so as to deduce the relation between the elevation precision and a vertical baseline; for double-base interference, analyzing coherence and the relationship between a vertical baseline and a critical baseline in combination with the critical baseline; obtaining the relation between the ratio of the vertical base line to the critical base line and the elevation accuracy; carrying out interference SAR time sequence deformation rate error analysis so as to derive a relation between deformation rate precision and each error source; deriving the influence of the incoherent noise on the deformation rate precision; and obtaining the relationship between the ratio of the coherence time base line to the revisit period and the deformation rate precision. The high-precision terrain and deformation measurement task requirement of the space-based SAR technology is met.

Description

Technical Field

[0001] The invention belongs to the field of radar measurement, and in particular relates to a space-based ultra-long baseline interferometric SAR system design method and device. Background Art

[0002] Interferometric Synthetic Aperture Radar (InSAR) technology can achieve two core functions, surface elevation measurement and deformation monitoring, by utilizing the phase difference of radar signals. It has become a key technical means in the fields of topographic mapping, geological disaster warning, and infrastructure safety assessment. The implementation of this technology relies on two typical observation modes:

[0003] 1. Single flyby mode: Two satellites or dual antennas simultaneously observe the same area to form a spatial baseline, and extract high-precision surface elevation information based on the principle of differential interferometry. Typical applications of this mode include digital elevation model (DEM) construction, glacier terrain mapping, etc.

[0004] 2. Repeated mode: Revisit the same area multiple times with a single or multiple satellites to form a time baseline, and use the heavy-track interferometric SAR technology to monitor slow surface deformation, such as fault creep and urban ground subsidence monitoring.

[0005] However, facing the increasing demand for terrain and deformation measurement accuracy, the existing interferometric SAR system still has the problem of mutual constraints between system design and measurement accuracy, and the analytical relationship between spatial baseline, temporal baseline and interferometric SAR measurement performance is still unclear; the extension of spatial baseline is beneficial to elevation measurement, and the extension of temporal baseline is beneficial to time series deformation measurement, but existing research has not yet given a clear definition and quantitative analysis of ultra-long spatial baseline and ultra-long time baseline.

[0006] For spatial baseline and elevation measurement, interferometric SAR obtains elevation information through spatial baseline, and its sensitivity is proportional to the length of spatial baseline. Spatial baseline is defined as the component of the baseline in the cross-track plane that is perpendicular to the line of sight of the radar beam (focus on the vertical baseline). Increasing the baseline length can improve the accuracy of elevation measurement, but at the same time it will produce decoherence, which will affect the accuracy of elevation measurement. The spatial baseline cannot be increased indefinitely. Therefore, it is urgent to establish a constraint relationship between the baseline length and the accuracy of elevation measurement and find the longest interferometric baseline.

[0007] For time baseline and deformation measurement, InSAR can measure surface deformation through periodic observation of the earth at different time periods. The time baseline is defined as the time difference between two images of the interference pattern. The coherent time baseline is defined as the time required for the temporal decoherence to decay from the initial to the original 1 / e (approximately equal to 0.36). Generally, the increase of the coherent time baseline can improve the measurement accuracy of the deformation rate, but the coherence will decrease with the increase of the time span, and the coherent time baseline cannot be increased indefinitely. Therefore, it is urgent to propose a space-based ultra-long baseline interferometric SAR system to clarify the definition of the ultra-long time baseline and guide the design and development of the space-based interferometric SAR system.

[0008] In summary, the existing InSAR technology faces dual constraints of baseline length and system design in terms of elevation and deformation measurement, and has not yet formed a definition method for ultra-long spatial baselines and ultra-long time baselines. How to define the high robustness observation of interferometric SAR under ultra-long baselines through innovative error analysis has become a technical problem that needs to be solved in the field of space-based radar remote sensing. Summary of the invention

[0009] In order to solve the above technical problems, the present invention proposes a space-based ultra-long baseline interferometric SAR system design method and device. First, taking bistatic interference as an example, the relationship between elevation accuracy and phase error and coherence is analyzed, and volume scattering decoherence and spatial baseline decoherence are mainly considered. Combined with the critical baseline, the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy is constructed, and the optimal vertical baseline length is analyzed, thereby defining the ultra-long spatial baseline; considering the relationship between the deformation rate measurement accuracy and atmospheric delay, decoherence noise, system phase noise, orbit error, and DEM error, the time series covariance matrix of the decoherence noise is analyzed in detail, and the spatial baseline decoherence and time decoherence are used. The coherent time baseline, revisit period, and long-term coherence are comprehensively considered to obtain the relationship between the ratio of the coherent time baseline to the revisit period and the deformation rate accuracy, thereby defining the ultra-long time baseline. The present invention can guide the design of a space-based ultra-long baseline interferometric SAR system, thereby meeting the high-precision terrain and deformation measurement task requirements of space-based SAR technology.

[0010] The principle on which the present invention relies is: taking the ratio of the vertical baseline to the critical baseline as the basis for defining the ultra-long spatial baseline, classifying the influencing factors of the elevation accuracy, and determining the relationship between the two; taking the ratio of the coherent time baseline to the revisit period as the basis for defining the ultra-long time baseline, classifying the influencing factors of the deformation rate accuracy, and determining the relationship between the two.

[0011] To achieve the above object, the technical solution of the present invention is:

[0012] A method for designing a space-based ultra-long baseline interferometric SAR system comprises the following steps:

[0013] Step 101: Analyze the relationship between elevation accuracy and phase error and coherence for bi-basic interferometry, so as to derive the relationship between elevation accuracy and vertical baseline;

[0014] Step 102, for dual-base interference, combined with the critical baseline, analyze the relationship between coherence and the vertical baseline and the critical baseline;

[0015] Step 103, combining step 101 and step 102, deriving the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy;

[0016] Step 104, performing an interferometric SAR time series deformation rate error analysis, thereby deriving a relationship between deformation rate accuracy and various error sources;

[0017] Step 105, derive the influence of the decoherence noise on the deformation rate accuracy; combine the relationship derived in step 104 to derive the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy.

[0018] The present invention also provides a space-based ultra-long baseline interferometric SAR system design device, comprising the following modules:

[0019] The derivation module analyzes the relationship between elevation accuracy and phase error and coherence for bi-basic interferometry, thereby deriving the relationship between elevation accuracy and vertical baseline;

[0020] The analysis module analyzes the relationship between coherence and vertical baseline and critical baseline in combination with the critical baseline for dual-base interference;

[0021] The ratio and elevation accuracy acquisition module combines the relationship derived by the derivation module and the relationship analyzed by the analysis module to derive the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy;

[0022] The error analysis module performs deformation rate error analysis on the interferometric SAR time series, thereby deriving the relationship between the deformation rate accuracy and each error source;

[0023] The relationship acquisition module derives the influence of decoherence noise on the deformation rate accuracy; combined with the relationship derived by the error analysis module, the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy is obtained.

[0024] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the above-mentioned method for designing a space-based ultra-long baseline interferometric SAR system are implemented.

[0025] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned method for designing a space-based ultra-long baseline interferometric SAR system.

[0026] Beneficial effects:

[0027] The present invention takes various error sources into consideration, focusing on the impact of incoherent noise on elevation and deformation accuracy, balancing the constraints between various factors, and gives the definitions of ultra-long spatial baseline and ultra-long time baseline, which can provide an important reference for designers of space-based interferometric SAR systems in designing system parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A flow chart of a method for designing a space-based ultra-long baseline interferometric SAR system according to an embodiment of the present invention;

[0029] Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e is the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy; Figure 2a For the case of a slope of -20°, Figure 2b For the case of a slope of -10°, Figure 2c For the case of a slope of 0°, Figure 2d For a slope of 10°, Figure 2e For the case of a slope of 20°;

[0030] Figure 3 This is the relationship between atmospheric delay, decoherence noise, system noise and total error and deformation rate measurement accuracy;

[0031] Figure 4a , Figure 4b , Figure 4c This is the influence diagram of the relationship between decoherence noise and coherence time baseline, revisit period, and long-term coherence on deformation measurement accuracy; among them, Figure 4a is the influence of the coherent time baseline on the deformation measurement accuracy, Figure 4b The influence of revisit period on deformation measurement accuracy is shown in Figure 2. Figure 4c The influence of long-term coherence on the deformation measurement accuracy;

[0032] Figure 5a , Figure 5b is the relationship between the coherence time baseline and the revisit period ratio and the deformation rate accuracy; where, Figure 5a is the two-dimensional relationship between the coherence time baseline, revisit period and deformation rate accuracy, Figure 5b Relationship between the coherence time baseline and the revisit period ratio and deformation rate accuracy. DETAILED DESCRIPTION

[0033] The following will use the schematic diagrams in the embodiments of the present invention to explain the technical solutions in the present invention more clearly and completely. Please note that all embodiments based on the present invention, as long as they can be understood and implemented by ordinary technicians in the field without paying additional innovative work, should be regarded as belonging to the protection scope of the present invention.

[0034] like Figure 1 As shown, one embodiment of the present invention discloses a method for designing a space-based ultra-long baseline interferometric SAR system, comprising the following steps:

[0035] Step 101: Taking bistatic interferometry as an example, analyze the relationship between phase error and elevation accuracy and coherence, and thus derive the relationship between elevation accuracy and vertical baseline, including:

[0036] The relationship between the elevation accuracy and phase error of bistatic interferometry is:

[0037] (1)

[0038] in, is the standard deviation of elevation accuracy, is the standard deviation of the phase error, is the wavelength, is the primary star slant distance, is the incident angle, is the vertical baseline.

[0039] The relationship between phase error and coherence is:

[0040] (2)

[0041] in, is the standard deviation of the phase error caused by decoherence, is the standard deviation of the phase error caused by other factors, For multiple views, For coherence.

[0042] From formula (1)-formula (2), we can get the relationship between elevation accuracy and vertical baseline:

[0043] (3)

[0044] Step 102: Taking dual-base interferometry as an example, combined with the critical baseline, the relationship between coherence and the vertical baseline and the critical baseline is analyzed, including:

[0045] Critical Baseline The expression is:

[0046] (4)

[0047] in, is the distance bandwidth, is the wavelength, is the primary star slant distance, is the incident angle, is the local slope angle, The speed of light.

[0048] Coherence The expression is:

[0049] (5)

[0050] in, is the quantization noise decorrelation coefficient, is the Doppler decorrelation coefficient, is the sidelobe decorrelation coefficient, is the registration error decorrelation coefficient, is the fuzzy decorrelation coefficient, is the thermal noise decorrelation coefficient, is the volume scattering decoherence coefficient, is the spatial baseline decoherence coefficient. In the above coherence coefficients, the volume scattering decoherence coefficient and the spatial baseline decorrelation coefficient Related to vertical baseline and critical baseline.

[0051] Volume scattering decoherence coefficient The expression is:

[0052] (6)

[0053] in, is the independent variable of integration, is the vegetation height, is an exponential function, is an imaginary unit, is the attenuation function of vegetation to electromagnetic waves, expressed as:

[0054] (7)

[0055] in, is the one-way extinction coefficient of electromagnetic waves in vegetation.

[0056] Spatial baseline decorrelation coefficient The expression is:

[0057] (8)

[0058] From formula (4) to formula (8), the relationship between coherence and vertical baseline and critical baseline can be obtained as follows:

[0059] (9)

[0060] Among them, the intermediate parameters , is the value The constant, Indicates that the independent variable is Function .

[0061] Step 103: Combining step 101 and step 102, the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy is obtained, including:

[0062] From formula (3), formula (4) and formula (9), we can get the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy:

[0063] (10)

[0064] Step 104: Performing an interferometric SAR time series deformation rate error analysis to derive the relationship between the deformation rate accuracy and various error sources, including:

[0065] Standard deviation of deformation rate measurement accuracy It is related to atmospheric delay, incoherence noise, system phase noise, orbit error, and DEM (digital elevation model) error. Specifically:

[0066] (11)

[0067] (12)

[0068] (13)

[0069] (14)

[0070] in, is the design matrix of the linear deformation model, such as , For the 1st, 2nd, ..., Nth time, is the covariance matrix of the deformation time series, is the atmospheric delay covariance matrix, is the incoherent noise covariance matrix, is the system phase noise covariance matrix, is the orbit error covariance matrix, is the DEM error covariance matrix, is the generalized inverse of the matrix, the superscript T is the transpose of the matrix, is a diagonal matrix, is the phase standard deviation of the residual atmospheric delay error, is the standard deviation of the system phase noise error, The number of time.

[0071] Step 105: deriving the influence of the decoherence noise on the deformation rate accuracy; combining with step 104, obtaining the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy, including:

[0072] Incoherent noise covariance matrix (Based on the small baseline set method) is:

[0073] (15)

[0074] (16)

[0075] in, Is the size of The design matrix of the phase estimation of the small baseline set method is, is the number of interference patterns, such as:

[0076] ;

[0077] is the covariance matrix of the interferometric stack of decoherent noise, is the standard deviation of the decoherence noise, is the inverse of the matrix. The standard deviation of the incoherent noise is The expression of coherence with the time series incoherence noise is:

[0078] (17)

[0079] in, For multiple views, is the coherence, the spatial baseline decorrelation coefficient Calculated by formula (8), is the temporal decorrelation coefficient, is the thermal noise decorrelation coefficient, is the signal-to-noise ratio, is the coherence time baseline, is the length of the time series, For the revisit cycle, is the number of time, is the long-term coherence coefficient.

[0080] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0081] Example 1

[0082] According to formula (10), simulation analysis is performed. First, the constant is defined , the speed of light , multi-view , distance to bandwidth , vegetation height , the one-way extinction coefficient of electromagnetic waves in vegetation , the standard deviation of phase error caused by other factors The relationship between the elevation accuracy and the ratio of the vertical baseline to the critical baseline is simulated when the slope is 0°, ±10°, ±20°, and the incident angle is 25°, 35°, and 45°. The results are as follows Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e As shown. Among them, Figure 2a For the case of a slope of -20°, Figure 2b For the case of a slope of -10°, Figure 2c For the case of a slope of 0°, Figure 2d For a slope of 10°, Figure 2e For the case of a slope of 20°. The improvement in elevation accuracy is reflected in the reduction of elevation error. As the ratio of the vertical baseline to the critical baseline increases, the elevation accuracy shows an overall trend of first increasing and then decreasing. For the same slope and different incident angles, the elevation error reaches the minimum at the same ratio of the vertical baseline to the critical baseline, that is, the elevation accuracy reaches the maximum at this time. For different cases of the same slope and the same incident angle, the elevation error changes with the slope and reaches the minimum when the ratio of the vertical baseline to the critical baseline is 24%-30%.

[0083] In SAR system design, the vertical baseline length used for interferometric height measurement is usually about 10% of the critical baseline. According to simulation experiments, when the vertical baseline is greater than 25%-30% of the critical baseline, the height accuracy will begin to decline. Here, in order to distinguish the boundary between long baseline and super long baseline, the vertical baseline is defined as 10% of the critical baseline as the conventional system, and when it exceeds 10%, it is a long baseline, and the super long baseline is twice the long baseline.

[0084] In summary, in areas with flat terrain, a long baseline is defined as a ratio of 10% to 20% between the vertical baseline and the critical baseline, and an extra-long baseline is defined as a ratio of 20% to 30% between the vertical baseline and the critical baseline. As the terrain becomes more complex and the slope increases, the elevation accuracy will decrease faster, considering the increased difficulty of phase unwrapping. In areas with complex terrain, a long baseline is defined as a ratio of 10% to 17% between the vertical baseline and the critical baseline, and an extra-long baseline is defined as a ratio of 17% to 25% between the vertical baseline and the critical baseline.

[0085] Example 2

[0086] First, the measurement accuracy of each error source and deformation rate is simulated. Figure 3 As shown. Time series length (i.e. time) Year, revisit cycle Day, coherent time baseline Day, long-term coherence coefficient , the phase standard deviation of the residual atmospheric delay error (Here, the atmospheric delay error refers to the error corrected by the mainstream atmospheric delay correction method), the standard deviation of the system phase noise error , the orbit error and DEM error are set to 0. It can be seen that the measurement accuracy increases with the increase of the time series length. The contribution of uncertainty is: atmospheric delay>decoherence noise>system noise. Among them, atmospheric delay, system phase noise, orbit error, and DEM error are all linearly positively correlated with the deformation measurement accuracy. Atmospheric delay belongs to the external environment error and can be designed independently of the interferometric SAR system; the system phase error and orbit error are so small that they can be ignored under the current engineering hardware level. Therefore, the present invention focuses on the impact of decoherence noise.

[0087] Secondly, the relationship between the decoherence noise and the coherence time baseline, revisit period, and long-term coherence is simulated to simulate its impact on the deformation measurement accuracy, such as Figure 4a , Figure 4b , Figure 4c As shown. Among them, Figure 4a is the influence of the coherent time baseline on the deformation measurement accuracy, Figure 4b The influence of revisit period on deformation measurement accuracy is shown in Figure 2. Figure 4c is the influence of long-term coherence on the deformation measurement accuracy. Year, revisit cycle Day, long-term coherence coefficient , coherence time baseline It can be seen that the decoherence noise is determined by the coherence time baseline, revisit period, and long-term coherence, and is nonlinearly correlated with the deformation measurement accuracy; the influence of the coherence time baseline and revisit period is dominant, and the influence of long-term coherence is the smallest.

[0088] Based on the above, the present invention simulates the relationship between the deformation rate accuracy and the coherence time baseline and the revisit period ratio, such as Figure 5a , Figure 5b As shown. Among them, Figure 5a is the two-dimensional relationship between the coherence time baseline, revisit period and deformation rate accuracy, Figure 5bThe relationship between the ratio of the coherent time baseline to the revisit period and the deformation rate accuracy. It can be seen that the two are nonlinear, and the larger the ratio, the more accurate the rate measurement. When the rate measurement accuracy reaches 1 mm / year, the corresponding ratio of the coherent time baseline to the revisit period is 3.85. Therefore, the present invention defines that the interferometric SAR system when the ratio of the coherent time baseline to the revisit period is ≥3.85 is an ultra-long time baseline interferometric SAR. At this time, the coherent time baseline is the time baseline length with a coherence greater than or equal to 0.36 (=1 / e), and this parameter depends on the radar wavelength, the type of terrain, etc. The ultra-long time baseline definition of this ratio is independent of the radar wavelength and can be used to guide the parameter design of the revisit period of the interferometric SAR system. For example: according to the type of terrain to be covered, after selecting the radar wavelength, calculate the coherent time baseline, and then select the revisit period required by the system according to the ultra-long time baseline principle.

[0089] The present invention also provides a space-based ultra-long baseline interferometric SAR system design device, comprising the following modules:

[0090] The derivation module, for bi-basic interferometry, analyzes the relationship between elevation accuracy and phase error and coherence, thereby deriving the relationship between elevation accuracy and vertical baseline;

[0091] Analysis module, for dual-base interferometry, combined with critical baseline, analyzes the relationship between coherence and vertical baseline and critical baseline;

[0092] The ratio and elevation accuracy acquisition module, combined with the derivation module and the analysis module, obtains the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy;

[0093] The error analysis module performs deformation rate error analysis on the interferometric SAR time series, thereby deriving the relationship between the deformation rate accuracy and each error source;

[0094] The relationship acquisition module derives the influence of decoherence noise on the deformation rate accuracy; combined with the error analysis module, the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy is obtained.

[0095] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the above-mentioned method for designing a space-based ultra-long baseline interferometric SAR system are implemented.

[0096] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-mentioned method for designing a space-based ultra-long baseline interferometric SAR system.

[0097] It should be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and interpreted scripting language JavaScript, etc.

[0098] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0099] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0100] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0101] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0102] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for designing a space-based ultra-long baseline interferometric SAR system, characterized in that: The steps include: Step 101: Analyze the relationship between elevation accuracy and phase error and coherence for bi-basic interferometry, so as to derive the relationship between elevation accuracy and vertical baseline; Step 102, for dual-base interference, combined with the critical baseline, analyze the relationship between coherence and the vertical baseline and the critical baseline; Step 103, combining step 101 and step 102, deriving the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy; Step 104, performing an interferometric SAR time series deformation rate error analysis, thereby deriving a relationship between deformation rate accuracy and various error sources; Step 105, derive the influence of the decoherence noise on the deformation rate accuracy; combine the relationship derived in step 104 to derive the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy.

2. The method for designing a space-based ultra-long baseline interferometric SAR system according to claim 1, characterized in that: The step 101 includes: obtaining the relationship between the elevation accuracy and the vertical baseline according to the relationship between the elevation accuracy and the phase error and the relationship between the phase error and the coherence of the dual-base interferometer.

3. The method for designing a space-based ultra-long baseline interferometric SAR system according to claim 2, characterized in that: The step 102 includes: The analysis utilizes an expression for a critical baseline; the coherence includes quantization noise decorrelation, Doppler decorrelation, sidelobe decorrelation, registration error decorrelation, blur decorrelation, thermal noise decorrelation, volume scattering decorrelation, and spatial baseline decorrelation.

4. The method for designing a space-based ultra-long baseline interferometric SAR system according to claim 3, characterized in that: The step 102 further includes: By analyzing the volume scattering decoherence and spatial baseline decoherence, the relationship between coherence, elevation accuracy, vertical baseline and critical baseline is obtained as follows: (9) (10) in, is the coherence, the intermediate parameter , is the value The constant, is the quantization noise decorrelation coefficient, is the Doppler decorrelation coefficient, is the sidelobe decorrelation coefficient, is the registration error decorrelation coefficient, is the fuzzy decorrelation coefficient, is the thermal noise decorrelation coefficient; is the standard deviation of elevation accuracy, is the speed of light, is the incident angle, is the local slope angle, is the distance bandwidth, is the vertical baseline, is the critical baseline, is the standard deviation of the phase error caused by other factors, For multiple views, is the one-way extinction coefficient of electromagnetic waves in vegetation, is the independent variable of integration, is the vegetation height, is an exponential function, is an imaginary unit, is the attenuation function of vegetation to electromagnetic waves, Indicates that the independent variable is Function .

5. The method for designing a space-based ultra-long baseline interferometric SAR system according to claim 1, characterized in that: The step 104 includes: Consider the relationship between deformation rate measurement accuracy and atmospheric delay, incoherence noise, system phase noise, orbit error, and DEM error.

6. A space-based ultra-long baseline interferometric SAR system design method according to claim 5, characterized in that: The step 105 includes: analyzing the covariance matrix of the time series of the decoherent noise; comprehensively considering the coherent time baseline, revisit period, and long-term coherence to obtain the relationship between the ratio of the coherent time baseline to the revisit period and the deformation rate accuracy.

7. The method for designing a space-based ultra-long baseline interferometric SAR system according to claim 6, characterized in that: The relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy is: (11) (12) (13) (14) (15) (16) (17) in, is the standard deviation of the deformation rate measurement accuracy, is the design matrix of the linear deformation model, is the covariance matrix of the deformation time series, is the atmospheric delay covariance matrix, is the incoherent noise covariance matrix, is the system phase noise covariance matrix, is the orbit error covariance matrix, is the DEM error covariance matrix, is the generalized inverse of the matrix, the superscript T is the transpose of the matrix, is a diagonal matrix, is the phase standard deviation of the residual atmospheric delay error, is the standard deviation of the system phase noise error, is the number of time, is the design matrix for phase estimation using the small baseline set method, is the covariance matrix of the interferometric stack of decoherent noise, is the standard deviation of the decoherence noise, is the inverse of the matrix, is the standard deviation of the decoherence noise, , For multiple views, For coherence; is the spatial baseline decorrelation coefficient, is the temporal decorrelation coefficient, is the thermal noise decorrelation coefficient, is the signal-to-noise ratio, is the coherence time baseline, is the length of the time series, For the revisit cycle, is the long-term coherence coefficient.

8. A space-based ultra-long baseline interferometric SAR system design device, characterized in that: Includes the following modules: The derivation module analyzes the relationship between elevation accuracy and phase error and coherence for bi-basic interferometry, thereby deriving the relationship between elevation accuracy and vertical baseline; The analysis module analyzes the relationship between coherence and vertical baseline and critical baseline in combination with the critical baseline for dual-base interference; The ratio and elevation accuracy acquisition module combines the relationship derived by the derivation module and the relationship analyzed by the analysis module to derive the relationship between the ratio of the vertical baseline to the critical baseline and the elevation accuracy; The error analysis module performs deformation rate error analysis on the interferometric SAR time series, thereby deriving the relationship between the deformation rate accuracy and each error source; The relationship acquisition module derives the influence of decoherence noise on the deformation rate accuracy; combined with the relationship derived by the error analysis module, the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy is obtained.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of a method for designing a space-based ultra-long baseline interferometric SAR system are implemented as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a method for designing a space-based ultra-long baseline interferometric SAR system as claimed in any one of claims 1 to 7 are implemented.

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