Spaceborne interferometric and differential interferometric sar implementation method and system based on formation flying

Abstract

The application provides a kind of based on the implementation method and system of spaceborne interferometric and differential interferometric SAR of heterogeneous formation, comprising: design heterogeneous system synchronization;Design heterogeneous system orbit formation configuration;Establish spaceborne interferometric SAR and differential interferometric SAR model, respectively solve absolute interferometric phase and differential interferometric phase containing terrain and deformation information;Establish spaceborne interferometric SAR and differential interferometric SAR error sensitivity model, calculate system error sensitivity in the process of interference processing;Establish heterogeneous system interferometric SAR calibration model.The application proposes two kinds of orbit formation configuration design of spaceborne interferometric SAR system based on fly-around mode and differential interferometric SAR system based on follow mode, breaks through the traditional heterogeneous interferometric SAR and differential interferometric SAR system, effectively solves the problems of low interference efficiency, long revisit period and difficult to realize business operation of single-satellite multi-pass interferometric SAR system, can greatly shorten the same wave bit observation period, significantly improves the data acquisition efficiency.

Description

Technical Field

[0001] This invention relates to the field of aerospace systems technology, specifically to a method and system for implementing spaceborne interferometric and differential interferometric SAR based on alien star formations. Background Technology

[0002] Synthetic Aperture Radar (SAR) is an active microwave imaging sensor. Compared to optical remote sensing, which is susceptible to lighting conditions and cloud / rain effects, SAR offers the unique advantage of all-weather, all-day Earth observation. Spaceborne SAR interferometric systems acquire two SAR images of the observation area from different perspectives, then perform interferometric processing to generate ground elevation information for the area. Differential interferometric SAR satellite systems acquire SAR image information through two or more repeated observations, then perform differential interferometric processing to generate surface deformation information.

[0003] Currently, the main systems that simultaneously realize spaceborne interferometric SAR and differential interferometric SAR include repeating orbit multi-pass interferometric SAR systems and dual-antenna interferometric SAR systems. The advantages of repeating orbit multi-pass interferometric SAR systems are relatively simple satellite and SAR payload design and sufficiently high satellite orbital maintenance accuracy. However, their disadvantages include severe decorrelation effects (time decorrelation, atmospheric loss decorrelation) and low interferometric efficiency, making operational implementation difficult. Dual-antenna interferometric SAR systems, on the other hand, offer high coherence and a stable effective baseline, but face significant challenges in satellite platform engineering implementation.

[0004] This invention was compared with existing technologies and the closest technological achievements both domestically and internationally. A search using the keywords "SAR," "interferometric SAR," and "differential interferometric SAR" yielded seven related patents, but these differ fundamentally from the implementation of this invention. The specific details are as follows:

[0005] The patent with publication number CN119439191A discloses a differential InSAR system, method, application and readable storage medium. This invention introduces a differential InSAR airborne system, but does not involve the design of a spaceborne differential interferometric SAR system.

[0006] The patent with publication number CN115951354 discloses a D-InSAR deformation monitoring method that integrates ascending and descending orbits. This invention proposes a method for monitoring surface deformation information by fusing ascending and descending orbit data from a data processing perspective, without considering satellite system design.

[0007] The patent with publication number CN117452402A discloses an interferometric SAR measurement method and system. This invention proposes an interferometric SAR measurement method from the perspective of data processing, but it is not applicable to satellite operational mode operation and promotion.

[0008] The patent with publication number CN115453520A discloses a method and device for measuring surface deformation based on dual-frequency multi-polarization differential interferometry. This invention optimizes the interferometric surface deformation measurement method for data processing flow, but does not consider satellite system design.

[0009] The patent with publication number CN110907932A discloses a method and system for analyzing factors affecting the accuracy of distributed InSAR satellite altimetry. This invention proposes an analysis of the impact of interferometric SAR altimetry on distributed satellites, but does not consider the design of interferometric SAR and differential interferometric SAR systems.

[0010] The patent with publication number CN107037428A discloses a method to improve the deformation extraction accuracy of spaceborne bistatic differential InSAR. This invention proposes a bistatic differential interferometric SAR data processing flow, but does not take into account the satellite system design.

[0011] In summary, given the problems of the existing technologies, researching a method and system for implementing spaceborne interferometric and differential interferometric SAR based on alien formations has become a critical task that urgently needs to be addressed. Summary of the Invention

[0012] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for implementing spaceborne interferometric and differential interferometric SAR based on alien formations.

[0013] According to the present invention, a method for implementing spaceborne interferometric and differential interferometric SAR based on alien star formations includes the following steps: Step S1, designing alien system synchronization; Step S2, designing alien system orbital formation configuration; Step S3, establishing spaceborne interferometric SAR and differential interferometric SAR models; Step S4, establishing spaceborne interferometric SAR and differential interferometric SAR error sensitivity models; Step S5, establishing alien system interferometric SAR calibration model.

[0014] Preferably, in step S1, the design of interstellar system synchronization includes: adopting a dual-satellite simultaneous observation strategy, controlling two satellites in the interstellar system to observe the same target with repeated orbital positions, repeated viewing angles, repeated working modes and repeated wavefront parameters, and establishing a time synchronization and phase synchronization mechanism between the interstellar systems to obtain radar image pairs that meet the requirements of interferometric coherence.

[0015] Preferably, in step S2, the orbital formation configuration of the alien system is designed, including: the primary satellite operates along a strict return orbit, and the secondary satellite orbits the primary satellite relative to the primary satellite according to the designed formation configuration; the binary system adopts a one-transmit, two-receiver configuration, with the primary satellite transmitting pulse signals and both the primary and secondary satellites simultaneously receiving echo signals; the binary system employs time synchronization, phase synchronization, and spatial synchronization design to ensure that the SAR operating time reference of the two satellites is consistent, the phase error of the SAR channels of the two satellites can be calibrated, and the beam pointing of the two satellites overlaps consistently; this is for the tasks of spaceborne interferometric SAR altimetry and differential interferometric SAR deformation measurement. To address functional differences, an integrated control mechanism for satellite formation modes is constructed. This mechanism employs phase adjustment and formation strategies to control the alien system to switch between follow-fly mode and fly-around mode. For the requirements of spaceborne interferometric SAR, the alien system is controlled to switch to fly-around mode and configured as a two-satellite formation flight configuration to form an effective spatial baseline. For the requirements of differential interferometric SAR, the alien system is controlled to switch to follow-fly mode, controlling the two satellites to operate in the same strict return orbit with a phase interval of 180°, and implementing strict return orbit control to keep them within the preset diameter range.

[0016] Preferably, in step S3, establishing the spaceborne interferometric SAR model includes: mathematically modeling the interferometric SAR system and establishing an interferometric elevation calculation model, wherein the calculation formula for the interferometric elevation is as follows:

[0017] in, h Elevation of ground point r Main star to ground point P distance, H The altitude of the satellite orbit. Let be the radius of curvature of the Earth, where is the cosine value of the lower angle. Determined based on the following set of relations:

[0018] in, Baseline tilt angle, The length of the binary star system's spatial baseline. For radar wavelength, This is the interference phase.

[0019] Preferably, in step S3, establishing a differential interferometric SAR model includes: setting... A The star is the satellite that conducts the first observation of the target area. B The satellites are those that conduct a second observation of the region after a revisit cycle. A The phase obtained from star observation is , B The phase obtained from star observation is The calculation formulas are as follows:

[0020]

[0021] in, and They represent A Star and B The slant distance of the star, Indicates the radar wavelength; Based on the above observations, establish the absolute interferometric phase. The calculation model is as follows:

[0022] Based on the absolute interference phase, a differential interference deformation phase model incorporating elevation error is established.

[0023] Preferably, the establishment of the differential interferometric deformation phase model including elevation error includes: in A Star and B If an earthquake occurs on the Earth's surface during the two star observations? The deformation displacement, projected onto the satellite's line-of-sight direction, is... The change in interference phase caused by deformation for:

[0024] Based on elevation error With elevation ambiguity Determine the phase components of the elevation error for:

[0025] The deformation phase component is superimposed with the elevation error phase component to obtain the deformation phase information of the alien system. for:

[0026] in, From a bottom perspective, B ⊥ This is the vertical baseline.

[0027] Preferably, in step S4, establishing a spaceborne interferometric SAR error sensitivity model includes: determining, based on the spaceborne interferometric SAR model, error sources affecting the accuracy of terrain elevation measurements, including: slant range. r Baseline length B Baseline tilt angle Interference phase Errors and satellite orbit measurement errors; by taking the partial derivative of the spaceborne interferometric SAR model, an interferometric SAR altimetry error sensitivity model is established, which is expressed as the following sensitivity vector:

[0028] in, h Elevation of ground point The main star's orbital position coordinates are used; the transfer function of each error source on the interferometric altimetry accuracy is obtained according to the error sensitivity model, and the system error allocation and spaceborne interferometric SAR model are verified based on the transfer function.

[0029] Preferably, in step S4, establishing the differential interferometric SAR error sensitivity model includes: determining the error sources affecting the accuracy of differential deformation measurement based on the differential interferometric SAR model, including: the orbital positioning error of the primary satellite. Primary star velocity error Slope distance measurement error Interferometric baseline error Interference phase error and DEM error Taking the partial derivative of the differential interferometric SAR model, a differential interferometric SAR deformation error sensitivity matrix model is established, which is expressed as:

[0030] in, The deformation displacement is represented; the transfer function of each error source to the deformation measurement accuracy is obtained according to the error sensitivity matrix model, and the error allocation and differential interferometric SAR model are verified based on the transfer function.

[0031] Preferably, in step S5, establishing an interferometric SAR calibration model for the alien system includes: determining that baseline vector error and interferometric phase error are the main factors affecting the accuracy of alien differential deformation measurement, and establishing a spaceborne SAR interferometric calibration model; during field calibration, based on ground control points and using the least squares method, performing independent parameter fine estimation of the interferometric phase error and baseline vector error; and compensating the absolute interferometric phase and interferometric baseline with the calibrated interferometric phase error and baseline vector error respectively, thereby completing the on-board parameter optimization.

[0032] This invention also provides a spaceborne interferometric and differential interferometric SAR implementation system based on alien star formations. This system can be implemented by executing the steps of the aforementioned spaceborne interferometric and differential interferometric SAR implementation method. In other words, those skilled in the art can understand the aforementioned spaceborne interferometric and differential interferometric SAR implementation method based on alien star formations as a preferred embodiment of the spaceborne interferometric and differential interferometric SAR implementation system based on alien star formations. The system includes: The alien synchronization module is used to control the time and phase synchronization of the primary and secondary stars in an alien system. The orbital formation control module is used to control the alien system to operate according to a preset interferometric formation configuration; The interferometric processing module is used to establish spaceborne interferometric SAR and differential interferometric SAR models, and to solve the absolute interferometric phase and the differential interferometric phase containing terrain and deformation information, respectively. The error analysis module is used to construct an error sensitivity model and calculate the system error sensitivity during the interference process. The calibration and compensation module is used to estimate the parameters of the interference phase error and the baseline vector error, and to compensate for the absolute interference phase and the interference baseline using the estimation results.

[0033] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes two orbital formation configuration designs: a spaceborne interferometric SAR system based on the fly-around mode and a differential interferometric SAR system based on the fly-following mode. Through the innovative orbital formation configuration design of alien systems, it breaks through the traditional alien interferometric SAR and differential interferometric SAR systems, effectively solving the problems of low interferometric efficiency, long revisit period, and difficulty in achieving operationalization of single-satellite multi-flying interferometric SAR systems. It can significantly shorten the observation period of the same wave position and significantly improve the data acquisition efficiency. This invention constructs comprehensive spaceborne interferometric SAR and differential interferometric SAR models and reveals the error sensitivity model mechanism, achieving accurate characterization of all-element deformation features and interferometric mapping information. Through a rigorous error estimation and compensation mechanism, the deformation accuracy of differential interferometric SAR can be improved to the millimeter level, significantly enhancing the accuracy of mapping and deformation monitoring. Attached Figure Description

[0034] 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: Figure 1 The flowchart illustrates a method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations, as provided by this invention.

[0035] Figure 2This is a schematic diagram of the geometric relationship of spaceborne interferometric SAR provided by the present invention.

[0036] Figure 3 This is a schematic diagram of the geometric relationship of differential interferometric SAR provided by the present invention. Detailed Implementation

[0037] 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.

[0038] Figure 1 A flowchart of a method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations provided by this invention is shown below. Figure 1 As shown, it includes the following steps: Step 1: Synchronization design of alien systems.

[0039] Furthermore, in this embodiment, a breakthrough is made in the alien distributed system architecture, and a method for simultaneously realizing interferometric SAR and differential interferometric SAR is proposed. Specifically, the alien system employs a two-satellite design in the same state, repeating orbital positions, viewing angles, modes, and wavefront parameters to observe the same target, providing radar image pairs with good coherence.

[0040] Step 2: Design of orbital formation configuration for alien systems.

[0041] Furthermore, in response to the requirements of differential interferometric SAR, this embodiment adopts the orbital formation design method of satellite-borne differential interferometric SAR in the follow-fly mode of the alien system, so that the nadir trajectories of the two satellites are spliced ​​together, that is, the two satellites operate on the same strict return orbit with a phase interval of 180°, and each performs strict return orbit control, and both are controlled within the pipe diameter range.

[0042] To address the requirements of interferometric SAR altimetry, this embodiment employs a spaceborne interferometric SAR orbital formation configuration design method under the alien system fly-around mode, specifically including: The primary satellite orbits along a strict return orbit, while the secondary satellite flies around the primary satellite in a designed formation configuration. The two satellites are configured with a single transmitter and dual receiver, with the primary satellite transmitting pulse signals and both the primary and secondary satellites simultaneously receiving echo signals. The dual-satellite system adopts time synchronization, phase synchronization and spatial synchronization design to ensure that the SAR working time reference of the two satellites is consistent, the phase error of the SAR channel of the two satellites can be calibrated, and the beam pointing of the two satellites overlaps in the same direction. To address the switching between spaceborne interferometric SAR altimetry and differential interferometric SAR deformation measurement functions, an integrated control design for satellite formation mode is proposed. This design employs two main strategies: phase adjustment and formation formation. The system can switch from follow-fly mode to fly-around mode, or vice versa, to meet the functional requirements of different missions.

[0043] Step 3: Establishment of spaceborne interferometric SAR and differential interferometric SAR models.

[0044] The schematic diagram of the geometric relationship of spaceborne interferometric SAR provided by this invention is as follows: Figure 2 As shown, a mathematical model of the spaceborne interferometric SAR system is further performed, and the interferometric elevation is represented as follows:

[0045] In the formula, h Elevation of ground point r Main star to ground point P distance, H The altitude of the satellite orbit. Let be the radius of curvature of the Earth, where is the cosine value of the lower angle. Determined based on the following set of relations:

[0046] in, Baseline tilt angle, The length of the binary star system's spatial baseline. For radar wavelength, This is the interference phase.

[0047] The differential interferometric SAR geometric relationship diagram provided by this invention is as follows: Figure 3 As shown, a mathematical model of the differential interferometric SAR system is further constructed, assuming... A The star is the satellite that conducts the first observation of the target area. B The satellites are those that conduct a second observation of the region after a revisit cycle. A The phase obtained from star observation is , B The phase obtained from star observation is The calculation formulas are as follows:

[0048]

[0049] in, and They represent A Star and B The slant distance of the star, Indicates the radar wavelength; Based on the above observations, establish the absolute interferometric phase. The calculation model is as follows:

[0050] Furthermore, based on the absolute interferometric phase, a differential interferometric deformation phase model incorporating elevation errors is established: A Star and B If an earthquake occurs on the Earth's surface during the two star observations? The deformation displacement, projected onto the satellite's line-of-sight direction, is... The change in interference phase caused by deformation for:

[0051] Based on elevation error With elevation ambiguity Determine the phase components of the elevation error for:

[0052] The deformation phase component is superimposed with the elevation error phase component to obtain the deformation phase information of the alien system. for:

[0053] in, From a bottom perspective, B ⊥ This is the vertical baseline.

[0054] Step 4: Establishment of error sensitivity models for spaceborne interferometric SAR and differential interferometric SAR.

[0055] Furthermore, according to the interferometric SAR altimetry model, the main factors affecting the accuracy of terrain elevation measurements include: slant range. r Baseline length B Baseline tilt angle Satellite orbit measurement error, interferometric phase error; Taking the partial derivative of the above equation, we establish an interferometric SAR altimetry error sensitivity model:

[0056] in, h Elevation of ground point The coordinates of the main star's orbital position; The transfer function of each error source on the interferometric altimetry accuracy is obtained based on the error sensitivity model, and the system error allocation and spaceborne interferometric SAR model are verified based on the transfer function.

[0057] Based on the differential interferometric SAR model equations, the main error sources affecting the accuracy of differential deformation measurements include: the orbital positioning error of the primary satellite. Speed ​​error Slope distance measurement error Interferometric baseline error Interference phase error DEM error ; By taking the partial derivative of the differential interference equation, a sensitivity equation matrix model for the error source is established:

[0058] in, Indicates the amount of deformation displacement; The transfer function of each error source to the deformation measurement accuracy is obtained based on the error sensitivity matrix model, and error allocation and verification of the differential interferometric SAR model are performed based on the transfer function.

[0059] Step 5: Establishment of interferometric SAR calibration model for alien systems.

[0060] Furthermore, based on the aforementioned error propagation sensitivity equation, the baseline vector and interferometric phase error are the main factors determining the accuracy of alien differential deformation measurements. Therefore, a spaceborne SAR interferometric calibration model is established to estimate and compensate for the interferometric phase error and baseline error. Since the error sources of the interferometric parameters are redundant, in order to improve the solution accuracy of the differential interferometric parameters during field calibration, the least squares method is used to perform precise parameter estimation of the interferometric phase error and baseline vector error independently based on the control points. The calibrated interferometric phase error and baseline vector error are used to compensate for the absolute interferometric phase and interferometric baseline, respectively, thereby optimizing the on-board parameters and improving the accuracy of interferometric altimetry and deformation measurement.

[0061] This invention also provides a spaceborne interferometric and differential interferometric SAR implementation system based on alien star formations. This system can be implemented by executing the steps of a spaceborne interferometric and differential interferometric SAR implementation method based on alien star formations. That is, those skilled in the art can understand the spaceborne interferometric and differential interferometric SAR implementation method based on alien star formations as a preferred embodiment of the spaceborne interferometric and differential interferometric SAR implementation system based on alien star formations. The system includes: The alien synchronization module is used to control the time and phase synchronization of the primary and secondary stars in an alien system. The orbital formation control module is used to control the alien system to operate according to a preset interferometric formation configuration; The interferometric processing module is used to establish spaceborne interferometric SAR and differential interferometric SAR models, and to solve the absolute interferometric phase and the differential interferometric phase containing terrain and deformation information, respectively. The error analysis module is used to construct an error sensitivity model and calculate the system error sensitivity during the interference process. The calibration and compensation module is used to estimate the parameters of the interferometric phase error and the baseline vector error, and to compensate for the absolute interferometric phase and the interferometric baseline using the estimation results.

[0062] 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.

[0063] 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 implementing spaceborne interferometric and differential interferometric SAR based on alien star formations, characterized in that, include: Step S1: Design a synchronization mechanism for an alien system; Step S2: Design the orbital formation configuration of the alien system; Step S3: Establish spaceborne interferometric SAR and differential interferometric SAR models; Step S4: Establish error sensitivity models for spaceborne interferometric SAR and differential interferometric SAR; Step S5: Establish an interferometric SAR calibration model for alien systems.

2. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S1, the design of alien system synchronization includes: By adopting a dual-satellite observation strategy, two satellites in a different system are controlled to observe the same target with repeated orbital positions, repeated viewing angles, repeated working modes, and repeated wavefront parameters. A time synchronization and phase synchronization mechanism between the different systems is established to obtain radar image pairs that meet the requirements of interferometric coherence.

3. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S2, designing the orbital formation configuration of the alien system includes: The primary star operates along a strict return orbit, while the secondary star orbits the primary star in a designed formation configuration. The binary system adopts a one-transmit, two-receive configuration, where the primary star transmits pulse signals and both the primary and secondary stars simultaneously receive echo signals. The dual-satellite system adopts time synchronization, phase synchronization and spatial synchronization design to ensure that the SAR working time reference of the two satellites is consistent, the phase error of the SAR channel of the two satellites can be calibrated, and the beam pointing of the two satellites overlaps in the same direction. To address the differences in mission functions between spaceborne interferometric SAR altimetry and differential interferometric SAR deformation measurement, an integrated control mechanism for satellite formation mode is constructed. This control mechanism employs phase adjustment and formation strategies to control the switching between following and circling modes of the alien system. To meet the requirements of spaceborne interferometric SAR, the alien system is controlled to switch to fly-around mode and configured as a two-satellite formation flight configuration to form an effective space baseline; To meet the requirements of differential interferometric SAR, the alien system is switched to follow-fly mode, and the two satellites are controlled to operate in the same strict return orbit with a phase interval of 180°. Strict return orbit control is implemented separately to keep them within the preset diameter range.

4. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S3, the spaceborne interferometric SAR model is established, including: A mathematical model is constructed for the interferometric SAR system, and an interferometric elevation calculation model is established. The formula for calculating the interferometric elevation is as follows: in, h Elevation of ground point r Main star to ground point P distance, H The altitude of the satellite orbit. Let be the radius of curvature of the Earth, where is the cosine value of the lower angle. Determined based on the following set of relations: in, Baseline tilt angle, The length of the binary star system's spatial baseline. For radar wavelength, This is the interference phase.

5. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S3, the differential interferometric SAR model is established, including: set up A The star is the satellite that conducts the first observation of the target area. B The satellites are those that conduct a second observation of the region after a revisit cycle. A The phase obtained from star observation is , B The phase obtained from star observation is The calculation formulas are as follows: in, and They represent A Star and B The slant distance of the star, Indicates the radar wavelength; Based on the above observations, an absolute interferometric phase is established. The calculation model is as follows: Based on the absolute interference phase, a differential interference deformation phase model incorporating elevation error is established.

6. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 5, characterized in that, The establishment of the differential interferometric deformation phase model including elevation error includes: exist A Star and B If an earthquake occurs on the Earth's surface during the two star observations? The deformation displacement, projected onto the satellite's line-of-sight direction, is... The change in interference phase caused by deformation for: Based on elevation error With elevation ambiguity Determine the phase components of the elevation error for: The deformation phase component is superimposed with the elevation error phase component to obtain the deformation phase information of the alien system. for: in, From a bottom perspective, B ⊥ This is the vertical baseline.

7. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S4, the error sensitivity model of spaceborne interferometric SAR is established, including: Based on the aforementioned spaceborne interferometric SAR model, the error sources affecting the accuracy of terrain elevation measurements are identified, including: slant range. r Baseline length B Baseline tilt angle Interference phase Errors and satellite orbit measurement errors; By taking the partial derivative of the spaceborne interferometric SAR model, an interferometric SAR altimetry error sensitivity model is established, which is expressed as the following sensitivity vector: in, h Elevation of ground point The coordinates of the main star's orbital position; The transfer function of each error source to the interferometric altimetry accuracy is obtained based on the error sensitivity model, and the system error allocation and spaceborne interferometric SAR model are verified based on the transfer function.

8. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S4, the differential interferometric SAR error sensitivity model is established, including: Based on the differential interferometric SAR model, the error sources affecting the accuracy of differential deformation measurement are identified, including: orbital positioning error of the primary satellite. Primary star velocity error Slope distance measurement error Interferometric baseline error Interference phase error and DEM error ; Taking the partial derivative of the differential interferometric SAR model, a differential interferometric SAR deformation error sensitivity matrix model is established, which is expressed as: in, Indicates the amount of deformation displacement; The transfer function of each error source to the deformation measurement accuracy is obtained based on the error sensitivity matrix model, and error allocation and verification of the differential interferometric SAR model are performed based on the transfer function.

9. The method for implementing spaceborne interferometric and differential interferometric SAR based on alien formations according to claim 1, characterized in that, In step S5, an interferometric SAR calibration model for the alien system is established, including: Baseline vector error and interferometric phase error were identified as the main factors affecting the accuracy of differential deformation measurement of alien stars, and a spaceborne SAR interferometric calibration model was established. During field calibration, based on ground control points and using the least squares method, independent parameter fine estimation is performed on the interferometric phase error and baseline vector error. The calibrated interferometric phase error and baseline vector error are used to compensate for the absolute interferometric phase and interferometric baseline, respectively, to complete the on-board parameter optimization.

10. A spaceborne interferometric and differential interferometric SAR implementation system based on alien star formations, characterized in that, include: The alien synchronization module is used to control the time and phase synchronization of the primary and secondary stars in an alien system. The orbital formation control module is used to control the alien system to operate according to a preset interferometric formation configuration; The interferometric processing module is used to establish spaceborne interferometric SAR and differential interferometric SAR models, and to solve the absolute interferometric phase and the differential interferometric phase containing terrain and deformation information, respectively. The error analysis module is used to build an error sensitivity model and calculate the system error sensitivity during the interference process. The calibration and compensation module is used to estimate the parameters of the interference phase error and the baseline vector error, and to compensate for the absolute interference phase and the interference baseline using the estimation results.

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