Alien differential interferometry method and system

Abstract

This invention provides a method and system for differential interferometry of alien celestial bodies, comprising: collaborative observation using an alien system composed of multiple satellites, all satellites adhering to the principle of common origin design to ensure coherence; orbital formation design for the alien system to shorten the effective revisit period; establishing a differential deformation error sensitivity model for the alien system to identify and quantify the main error sources; accurately estimating and compensating for key system errors based on the error sensitivity model; and finally, establishing and solving the deformation model of the alien differential system after error compensation to obtain high-precision surface deformation information. This invention also provides a system for executing this method. This invention significantly improves the timeliness of deformation monitoring through multi-satellite collaboration and ensures measurement accuracy through systematic error processing, making it suitable for scenarios such as emergency response and long-term dynamic monitoring.

Description

Technical Field

[0001] This invention relates to the field of satellite remote sensing technology, and in particular to a differential interferometry method and system for measuring different stars. Background Technology

[0002] Synthetic Aperture Radar (SAR) is an active microwave imaging sensor. Compared to optical remote sensing, which is affected by lighting conditions and cloud / rain, SAR offers the unique advantage of all-weather, all-day Earth observation. Differential Interferometric SAR satellite systems acquire surface imagery and deformation information through repeated observations. Specifically, differential interferometric synthetic aperture radar technology is an effective means of accurately retrieving minute surface deformations (such as subsidence, landslides, volcanic activity, etc.) by performing phase difference processing on two or more synthetic aperture radar images of the same area acquired at different times. This technology plays a crucial role in areas such as urban land subsidence monitoring, geological disaster early warning, and infrastructure health diagnosis.

[0003] Currently, differential interferometric SAR (DISAR) systems are mainly classified into three observation modes: single-satellite multiple-pass interferometric SAR with heavy orbit, dual-antenna single-pass interferometric SAR, and heterogeneous differential interferometric SAR systems. Single-satellite heavy-orbit interferometric SAR systems use a single-satellite observation method. Due to the long return period of a single satellite, there is complete decoupling between two observation images, resulting in poor interferometric performance. Dual-antenna single-pass interferometric SAR systems achieve heavy-orbit interferometry, but at a high system cost. Heterogeneous differential interferometric systems use two satellites in orbital formation to maintain alignment. By repeatedly observing the same target along the same orbit, the return period of the two satellites at the same wavelength is effectively reduced by half compared to a single satellite.

[0004] This invention was compared with existing technologies and the closest technological achievements both domestically and internationally. A search using the keywords "alien system," "SAR," and "differential interferometry" yielded five related patents, but these differ fundamentally from the implementation of this invention. The specific details are as follows: The patent document "Method and Equipment for Measuring Surface Deformation Based on Dual-Frequency Multi-Polarization Differential Interferometry" (2022, Patent Application No.: 202211318675.1) optimizes the interferometric surface deformation measurement method for data processing flow, but does not consider system design.

[0005] The patent document “Differential InSAR System, Method, Application and Readable Storage Medium” (2025, Patent Application No. 202510024960.X) describes an airborne differential InSAR system, but does not involve the design of a spaceborne differential interferometric SAR system.

[0006] The patent document “A wide-scale refined remote sensing method for surface deformation based on deep fusion of multi-dimensional electromagnetic information” (2023, patent application number 202311482394.4) proposes a method for monitoring surface deformation information by fusion of multiple information from the perspective of data processing, but does not consider system design.

[0007] The patent document "A D-InSAR Deformation Monitoring Method Based on Fusion of Ascending and Descending Orbits" (2023, Patent Application No. 202310108353.2) proposes a method for monitoring surface deformation information by fusing ascending and descending orbit data from the perspective of data processing, but does not consider system design.

[0008] The patent document “A method to improve the deformation extraction accuracy of spaceborne bistatic differential InSAR” (2017, patent application number 201710187861.9) proposes a bistatic differential interferometric SAR data processing flow, but does not take into account the design of the bistatic system.

[0009] In summary, traditional differential interferometric synthetic aperture radar (DISAR) technology typically relies on a single satellite repeatedly observing a target area within a fixed revisit period. However, this approach has inherent drawbacks. Firstly, it suffers from insufficient timeliness; revisit periods of several days to tens of days prevent the timely capture of sudden or rapidly evolving deformation processes. In scenarios such as emergency disaster relief or critical infrastructure monitoring, this delay can lead to missed opportunities for optimal response. Secondly, it results in decreased coherence. The longer the time interval between two observations, the greater the changes in surface cover (e.g., vegetation, water bodies) and atmospheric conditions, leading to reduced coherence between radar images and severely impacting the accuracy and reliability of interferometry.

[0010] Therefore, how to shorten the effective observation time interval and ensure high-quality interferometric data while improving the timeliness of deformation information acquisition is a technical problem that urgently needs to be solved in the current field. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the present invention aims to provide a differential interferometry method and system for monitoring surface deformation, which solves the technical problems of low timeliness in surface deformation monitoring and image decoherence caused by long satellite revisit periods in existing differential interferometric synthetic aperture radar technology, so as to achieve surface deformation monitoring with higher observation frequency and higher measurement accuracy.

[0012] A differential interferometry method for extraterrestrial objects provided by the present invention includes: Following the principle of homogeneous design, an alien system consisting of multiple synthetic aperture radar satellites was constructed, and the orbital formation of the alien system was designed. A differential deformation error sensitivity model for the alien system is established to identify and quantify the main error sources affecting the accuracy of deformation measurement. Based on the aforementioned error sensitivity model, the key system errors are accurately estimated and compensated. A deformation model of an alien differential system after error compensation is established and solved to obtain surface deformation information.

[0013] Preferably, the homogeneous design principle includes: the payload system, operating parameters, repeating orbit positions, repeating perspectives, repeating operating modes, and repeating wavelet parameters of all satellites within the heterogeneous system are kept consistent. The ground processing systems of all satellites within the alien system are also configured to process data from any satellite and support the same imaging modes, including but not limited to strip mode, spotlight mode, or scan mode.

[0014] Preferably, the orbital formation design includes: adopting a follow-fly formation configuration so that all satellites in the alien system operate on the same strict return orbit, and shortening the revisit period of a single satellite to one-Nth of the original period through the design of orbital phase intervals, where N is the number of satellites.

[0015] Preferably, when the alien system consists of two satellites, the orbital phase interval between the two satellites is 180 degrees; When the alien system consists of four satellites, the orbital phases of the four satellites are evenly spaced at 90 degrees.

[0016] Preferably, establishing the alien differential deformation error sensitivity model includes: First, we establish the phase deformation equations for the absolute interference phase of the alien star, as follows:

[0017] In the formula, The Doppler center frequency of the main star and These represent the position and velocity vectors of the primary star, respectively. and These represent the observation times of the alien planets. For the target position vector, For alien baseline vectors, This is an absolute interference phase of aliens. For radar wavelength, It is the Earth's equatorial radius. It is the ground elevation. The Earth's flattening factor, R1 represents the slant range, where R1 is the deformation component along the radar line of sight. Then, based on the equations, the main error sources affecting the accuracy of deformation measurement were identified, including: the orbital positioning error of the primary star. Speed ​​error The radar system's own slant range measurement error Interferometric baseline error and elevation errors of external reference data ; Finally, by taking partial derivatives of the phase deformation equations with respect to each error variable, a sensitivity equation matrix model for the error source is established:

[0018] Where F is the error source for each term. For deformation measurement accuracy The transfer function.

[0019] Preferably, the accurate estimation and compensation of key system errors includes: During the field calibration phase, ground control points with known precise coordinates are used to perform precise parameter estimation of the interferometric phase error and baseline vector error. The calibrated interferometric phase error and baseline vector error are then used to compensate for the subsequently measured absolute interferometric phase and interferometric baseline, respectively, in order to optimize the on-board parameters.

[0020] Preferably, establishing and solving the deformation model of the alien differential system includes: Phase obtained from observations of the primary star over the same region Phase obtained from observations of the region after a revisit cycle of the star. Calculate the absolute interference phase of alien stars The formulas are as follows:

[0021]

[0022] in, R 1 and R 2 represents the slant distance between the primary star and the secondary star. λ Represents the radar wavelength; The change in interference phase caused by deformation and r is directly proportional, as shown in the following formula:

[0023] Among them, the surface deformation and displacement of the primary and secondary star systems during the two observation periods are: d, the displacement projected onto the satellite line of sight towards the LOS deformation is r; Considering the deformation phase caused by elevation error, it is:

[0024] in, For elevation error, h amb Elevation ambiguity; The interferometric deformation phase model of the alien system is:

[0025] in, This is the downward viewpoint, and B⊥ is the vertical baseline.

[0026] According to the present invention, a differential interferometry system for extraterrestrial objects includes: Module M1: Following the principle of homogeneous design, a heterogeneous system consisting of multiple synthetic aperture radar satellites was constructed; Module M2: Designs orbital formations for the alien system; Module M3: Establish a differential deformation error sensitivity model for the alien system to identify and quantify the main error sources affecting the accuracy of deformation measurement; Module M4: Based on the aforementioned error sensitivity model, accurately estimate and compensate for key system errors; Module M5: Establishes and solves the deformation model of the alien differential system after error compensation, thereby obtaining surface deformation information.

[0027] Preferably, the homogeneous design principle includes: the payload system, operating parameters, repeating orbit positions, repeating perspectives, repeating operating modes, and repeating wavelet parameters of all satellites within the heterogeneous system are kept consistent. The ground processing systems of all satellites within the alien system are also configured to process data from any satellite and support the same imaging modes, including but not limited to strip mode, spotlight mode, or scan mode.

[0028] Preferably, the orbital formation design includes: adopting a follow-fly formation configuration so that all satellites in the alien system operate on the same strict return orbit, and shortening the revisit period of a single satellite to one-Nth of the original through the design of orbital phase intervals, where N is the number of satellites; When the alien system consists of two satellites, the orbital phase interval between the two satellites is 180 degrees; When the alien system consists of four satellites, the orbital phases of the four satellites are evenly spaced at 90 degrees.

[0029] Compared with the prior art, the present invention has the following beneficial effects: 1. The differential interferometry method for alien systems of the present invention adopts the same source design and orbit formation design of alien systems to achieve repeated observation of alien systems along the same orbit. It solves the problems of low interferometry efficiency, long replay cycle and difficulty in operationalization of single-satellite multi-pass interferometric SAR systems. It can effectively shorten the observation cycle of single-satellite systems at the same wave position by half, and can capture and monitor surface deformation more timely. It is particularly suitable for emergency response and dynamic monitoring scenarios.

[0030] 2. This invention reveals the mechanism of the differential deformation error sensitivity model for alien stars, proposes a precise estimation method for differential deformation errors of alien stars, realizes the establishment of deformation models for alien differential systems, and solves the problem of low accuracy of deformation phase information in single-star multi-pass interferometric SAR and dual-antenna single-pass interferometric SAR systems. It can improve the deformation accuracy of differential interferometric SAR to the centimeter level.

[0031] 3. This invention provides a complete technical solution from satellite system design, orbit formation, mathematical modeling, error calibration to deformation calculation. It has a closed-loop logic, strong operability, and can support ground processing systems to achieve high-precision, fixed-period, and long-term continuous surface deformation measurement. It has broad application prospects in fields such as land surveying, disaster prevention and control, and resource exploration. Attached Figure Description

[0032] 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 This is a flowchart illustrating a differential interferometry method for extraterrestrial objects provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the geometric relationship of an interference deformation model provided in an embodiment of the present invention. Detailed Implementation

[0033] 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.

[0034] Example 1 This embodiment provides a differential interferometry method based on a binary satellite system and its corresponding system implementation, illustrating how to achieve high-timeliness and high-precision monitoring of Earth's surface deformation through two cooperating satellites. Figure 1 As shown, the alien differential interferometry method of the present invention includes alien system homology construction, orbit formation construction, error sensitivity model establishment, data acquisition and error estimation, and deformation measurement and model establishment.

[0035] In the co-origin construction step of the alien system, an alien system consisting of two synthetic aperture radar (SAR) satellites, referred to as Satellite A and Satellite B for ease of description, was constructed. To ensure the success rate and accuracy of subsequent interferometric processing, Satellite A and Satellite B followed the co-origin design principle, repeatedly observing the same target with repeated orbital positions, repeated viewing angles, repeated modes, and repeated wavefront parameters. This provided radar image pairs with good coherence for the ground system to perform differential interferometric processing, obtaining more timely deformation information. This required that the core payloads (SAR systems) of the two satellites maintain a high degree of consistency in design and manufacturing. Specifically, the radar center frequencies of both satellites were set to the same X-band (e.g., 9.65 GHz) to ensure consistency in the interaction characteristics between electromagnetic waves and the Earth's surface. Furthermore, key operating parameters such as transmission bandwidth, pulse repetition frequency, antenna size and beam pointing range, and polarization mode (e.g., single-polarization HH or VV, dual-polarization HH+HV or VV+VH, or even full polarization mode) were designed to be completely identical or within extremely small tolerances. The ground processing systems for both satellites are also configured to process data from either satellite and support the same imaging modes, including but not limited to strip, spotlight, or scan modes. Understandably, this shared-source design is the physical basis for acquiring high-quality, highly coherent interferometric image pairs, minimizing systematic phase deviations introduced by instrument differences and providing an ideal data source for subsequent differential interferometric processing.

[0036] Accordingly, in the alien system orbit formation construction step, to ensure the coherence of the alien image pairs, the alien system must adhere to strict orbital regression design and pipeline control, and the orbits of satellites A and B were designed for formation. Satellites A and B are deployed on the same strict regression orbit. A strict regression orbit means that after a fixed regression period (designed as 12 days in this embodiment), the trajectory of the satellite's nadir point will precisely repeat. To improve observation timeliness, satellites A and B adopt a follow-fly formation configuration, and the phase interval on the orbit is set to 180°. Thus, if satellite A flies over a target area at time T0, satellite B will fly over the same target area 6 days after T0 (i.e., half of the regression period), thereby shortening the effective observation revisit period for any point on the ground from 12 days for a single satellite to 6 days. To maintain this precise orbital configuration, both Satellite A and Satellite B are equipped with independent orbit control systems. These systems utilize onboard thrusters to periodically perform orbit maintenance maneuvers based on precise orbit determination data and commands from ground stations, ensuring that their respective ground point trajectories are always constrained within a preset diameter range. This rigorous orbital control guarantees that image pairs acquired at different times have extremely small spatial baselines, another crucial prerequisite for differential interferometry.

[0037] The steps for establishing an error sensitivity model aim to accurately identify and quantify the impact of various error sources on the final deformation measurement results. Figure 2 This demonstrates the basic geometric relationships in interferometry. In a single interferometric observation, there exists a primary star and a secondary star (e.g., the observation of star A at time T0 is the primary image, and the observation of star B at time T0+6 is the secondary image), which, together with the target point on the Earth's surface, constitute the interferometric geometry.

[0038] Based on this geometric relationship, a set of phase deformation equations for the absolute interference phase of alien stars can be established, as follows:

[0039] In the formula, The Doppler center frequency of the main star and These represent the position and velocity vectors of the primary star, respectively. and These represent the observation times of the alien planets. For the target position vector, For alien baseline vectors, This is an absolute interference phase of aliens. For radar wavelength, It is the Earth's equatorial radius. It is the ground elevation. The Earth's flattening factor, R1 represents the slant range, where R1 is the deformation component along the radar line of sight. 。

[0040] By analyzing the above phase deformation equations, the main error sources affecting the accuracy of deformation measurement can be identified, including: the orbital positioning error of the primary star. and speed error Both factors affect the accuracy of the baseline vector; the radar system's own slant range measurement error... Interferometric baseline error This is a direct reflection of track error; and the elevation error of external reference data. To quantify the impact of these errors, partial derivatives are taken with respect to each error variable in the phase deformation equations, thus establishing a sensitivity equation matrix model for the error source:

[0041] Where F is the error source for each term. For deformation measurement accuracy The transfer function.

[0042] Based on the above theoretical model, the data acquisition and error fine estimation steps proceed. According to error sensitivity analysis, the interferometric baseline vector error and the systematic interferometric phase error are the key factors determining the accuracy of differential deformation measurement of extraterrestrial satellites, and they must be accurately calibrated and compensated. Since the error sources of interferometric parameters are redundant, an field calibration task is performed before or during the system's regular operational phase. A geologically stable area with distinct characteristics is selected as the calibration field, and multiple ground control points are pre-deployed within this field, such as artificial corner reflectors with strong radar backscattering capabilities, or sites equipped with high-precision global navigation satellite system receivers. The three-dimensional coordinates of these control points can achieve millimeter-level accuracy through long-term observation. During field calibration, to improve the solution accuracy of differential interferometric parameters, the interferometric phase error and baseline vector error are independently finely estimated based on the control points. The calibrated interferometric phase error and baseline vector error are then used to compensate for the absolute interferometric phase and interferometric baseline, respectively, completing the optimization of on-board parameters and improving deformation accuracy. The establishment of the interferometric parameter fine estimation model includes the following steps: Step 1: Select multiple control points i (i≥5) on the alien single-view complex image; Step 2: Obtain the interference phase of the alien differential interferometer at each control point. and baseline vector The initial value; Step 3: Combining the sensitivity equation of the model with the least squares criterion, derive the interferometric phase error. The optimal solution for the baseline vector error correction Δb; Step 4: Compensate the absolute interferometric phase and interferometric baseline with the calibrated interferometric phase error and baseline error respectively, thus obtaining the calibrated absolute interferometric phase. The baseline vector is .

[0043] Finally, in the deformation measurement and model building steps, this method is applied to a practical monitoring task, such as monitoring a potential landslide hazard area. Assume that satellite A acquires a synthetic aperture radar image of the area at time T1, and satellite B acquires a second image at time T1+6. The heterogeneous system consists of satellites A and B, which are of the same origin design. Satellite A acquires a phase image of the same region. The phase information obtained from observations of this region by satellite B after its revisit cycle is The formula is as follows:

[0044] R 1 and R 2 represents the slant distance between satellites A and B. λ This represents the radar wavelength. Therefore, the absolute interferometric phase of the alien star... for

[0045] The surface deformation and displacement of the A and B satellite systems during the two observation periods were as follows: d The deformation displacement projected onto the satellite line-of-sight (LOS) is r The amount of change in the interference phase caused by deformation and r Proportional, expressed by the formula: Furthermore, considering the deformation phase caused by elevation error, ,in For elevation error, h amb For elevation ambiguity, the interferometric deformation phase model of the alien system is: ,in From a bottom perspective, B ⊥ This is the vertical baseline.

[0046] In summary, this embodiment doubles the monitoring timeliness through dual-satellite collaborative observation, and ensures high accuracy of measurement results through systematic error modeling and calibration compensation, thereby verifying the effectiveness and superiority of this technical solution.

[0047] The alien differential deformation method proposed in this invention obtains more timely deformation information by repeatedly observing the same target along the same orbit of the alien and jointly processing alien image data. It supports ground processing to achieve high-precision, fixed-period, and long-term continuous surface deformation measurement, and has promotion and practical value.

[0048] Example 2 This embodiment provides a variant of the differential interferometry method based on a four-satellite system, illustrating that the technical solution of this invention has good scalability and can further improve the timeliness of surface deformation monitoring by increasing the number of satellites, thereby meeting the need for higher-frequency monitoring of rapid deformation processes (such as volcanic activity, post-earthquake deformation, and mining subsidence). This embodiment also follows... Figure 1 The overall process is shown, but it has its unique aspects in system construction and orbital formation.

[0049] In the homogeneous system construction step, this embodiment constructs a homogeneous system consisting of four satellites: A, B, C, and D. Similar to the technical approach in Embodiment 1, these four satellites also strictly adhere to the homogeneous design principle, ensuring that their onboard synthetic aperture radar payloads maintain a high degree of consistency in all key technical parameters. For example, they all employ C-band radar and have the same bandwidth and operating mode configuration. This provides data consistency assurance for subsequent interferometry processing between any two satellites.

[0050] In the orbital formation construction steps of the alien system, this embodiment employs a more compact formation design for the orbits of the four satellites. The four satellites are also deployed on the same strictly recurrent sun-synchronous orbit, assuming a single-satellite return period of 12 days. Unlike the binary configuration of Embodiment 1, the phases of the four satellites in this embodiment are designed to be evenly spaced at 90-degree intervals, forming an equally spaced "following constellation." From the perspective of Earth observation, if satellite A flies over a target area at time T0, satellite B will fly over the area 3 days after T0 (1 / 4 of the 12-day period), satellite C will fly over 6 days after T0, and satellite D will fly over 9 days after T0. Then, satellite A will return 12 days after T0. Through this design, the effective observation revisit period for any ground target is drastically shortened from 12 days for a single satellite to 3 days, doubling the timeliness compared to the binary system of Embodiment 1. Similarly, each satellite uses its own independent orbit control system to ensure that its nadir trajectory remains within a pre-set orbital channel, thus guaranteeing long-term, stable small-space baseline conditions.

[0051] In subsequent steps such as error sensitivity model establishment, data acquisition and error fine estimation, and deformation measurement and model establishment, the core theories and methods remain consistent with those in Example 1. It is understood that the error sensitivity model is applicable to interferometric pairs consisting of any two of the four satellites. The error fine estimation process can also be achieved by acquiring data from all four satellites in the calibration field and jointly solving multiple different interferometric pairs (such as AB pairs, AC pairs, BD pairs, etc.) to obtain more robust and accurate system error parameters.

[0052] The significant advantage of this embodiment lies in the application of deformation measurement and model solving steps. Due to its ultra-high frequency observation capability of 3 days, this embodiment can not only acquire the deformation field at a single time interval, but also construct a high-density time-series deformation history. For example, when monitoring an active fault, the system can continuously acquire synthetic aperture radar images at T0, T0+3 days, T0+6 days, T0+9 days, T0+12 days, etc., and use these data to construct a series of short-time baseline (3-day) interferometric pairs, such as (T0, T0+3), (T0+3, T0+6), (T0+6, T0+9), etc.

[0053] Specifically, this high-density time-series data stream offers the following advantages: 1. Capturing rapid deformation processes: The 3-day interval is sufficient to capture many rapid, nonlinear deformation processes that traditional differential interferometry techniques cannot observe, such as the acceleration phase of slow slip events or the initiation phase of landslides triggered by heavy rainfall. 2. Extremely high coherence: Due to the extremely short time interval, changes in surface cover (such as vegetation) and atmospheric conditions are very small, and the coherence of most surfaces can be well preserved. This allows for the acquisition of high-quality interferometric fringes even in areas with dense vegetation cover, thus greatly expanding the applicability of the technique. 3. Strong atmospheric noise suppression capability: By performing time-series analysis on this series of continuous differential interferograms (e.g., using permanent scatterer interferometry or small baseline set techniques), deformation signals and atmospheric delay signals with different spatiotemporal characteristics can be effectively separated. Atmospheric delay typically manifests as random noise in time, while surface deformation has temporal continuity or trends. Through time-series filtering or model fitting, the influence of atmospheric noise can be greatly reduced, thereby extracting purer and more reliable deformation rates and cumulative deformation. 4. Resolving Phase Unwrapping Ambiguity: High-density observation sequences facilitate unwrapping in the time dimension. When spatial unwrapping encounters difficulties, deformation trends at previous and subsequent time points can be referenced to aid in judgment, thereby improving the accuracy and robustness of phase unwrapping.

[0054] In summary, this embodiment expands the alien system to a four-star formation, thereby enhancing the timeliness of observations and enabling high-precision time-series deformation analysis. This strengthens the monitoring and understanding of dynamic processes on the Earth's surface and provides strong technical support for early warning and emergency response to geological disasters.

[0055] Example 3 The present invention also provides a differential interferometry system for alien stars, which can be implemented by executing the process steps of the differential interferometry method for alien stars. That is, those skilled in the art can understand the differential interferometry method for alien stars as a preferred embodiment of the differential interferometry system for alien stars.

[0056] According to the present invention, a differential interferometry system for extraterrestrial objects includes: Module M1: Following the principle of homogeneous design, a heterogeneous system consisting of multiple synthetic aperture radar satellites was constructed. This homogeneous design principle includes ensuring that all satellites within the heterogeneous system maintain consistent payload systems, operating parameters, repeating orbital positions, repeating viewpoints, repeating operating modes, and repeating spectral parameters. The ground processing systems of all satellites within the heterogeneous system are also configured to process data from any satellite and support the same imaging modes, including but not limited to strip mode, spotlight mode, or scan mode.

[0057] Module M2: Designs the orbital formation for the alien system. The orbital formation design includes: adopting a follow-fly formation configuration so that all satellites within the alien system operate on the same strict return orbit, and shortening the revisit period of a single satellite to one-Nth of its original value through orbital phase spacing design, where N is the number of satellites; when the alien system consists of two satellites, the orbital phase spacing between the two satellites is 180 degrees; when the alien system consists of four satellites, the orbital phase spacing between the four satellites is uniformly 90 degrees.

[0058] Module M3: Establishes a differential deformation error sensitivity model for the alien system to identify and quantify the main error sources affecting the accuracy of deformation measurements. Establishing the alien differential deformation error sensitivity model includes: First, establishing the phase deformation equations for the alien absolute interferometric phase, as follows:

[0059] In the formula, The Doppler center frequency of the main star and These represent the position and velocity vectors of the primary star, respectively. and These represent the observation times of the alien planets. For the target position vector, For alien baseline vectors, This is an absolute interference phase of aliens. For radar wavelength, It is the Earth's equatorial radius. It is the ground elevation. The Earth's flattening factor, Let R1 represent the deformation component along the radar line of sight and R1 represent the slant range. Then, based on the equations, the main error sources affecting the accuracy of deformation measurement are identified, including: the orbital positioning error of the primary satellite. Speed ​​error The radar system's own slant range measurement error Interferometric baseline error and elevation errors of external reference data Finally, partial differentials are performed on the phase deformation equations with respect to each error variable to establish a sensitivity equation matrix model for the error source:

[0060] Where F is the error source for each term. For deformation measurement accuracy The transfer function.

[0061] Module M4: Based on the aforementioned error sensitivity model, accurately estimates and compensates for key system errors. This accurate estimation and compensation includes: during the field calibration phase, using ground control points with known precise coordinates, precisely estimating the parameters of the interferometric phase error and baseline vector error; and then using the calibrated interferometric phase error and baseline vector error to compensate for the subsequently measured absolute interferometric phase and interferometric baseline, respectively, to optimize the on-board parameters.

[0062] Module M5: Establishes and solves the deformation model of the alien differential system after error compensation, thereby obtaining surface deformation information. Establishing and solving the alien differential system deformation model includes: based on the phase obtained from observations of the same region by the primary star. Phase obtained from observations of the region after a revisit cycle of the star. Calculate the absolute interference phase of alien stars The formulas are as follows:

[0063]

[0064] in, R 1 and R 2 represents the slant distance between the primary star and the secondary star. λ Represents the radar wavelength. The amount of change in the interference phase caused by deformation is related to... r is directly proportional, as shown in the following formula:

[0065] Among them, the surface deformation and displacement of the primary and secondary star systems during the two observation periods are: d, the displacement projected onto the satellite line of sight towards the LOS deformation is r. Considering the deformation phase caused by elevation error, it is:

[0066] in, For elevation error, h amb Let be the elevation ambiguity. Then the interferometric deformation phase model of the alien system is:

[0067] in, This is the downward viewpoint, and B⊥ is the vertical baseline.

[0068] 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.

[0069] 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 differential interferometry method for extraterrestrial objects, characterized in that, include: Following the principle of homogeneous design, a heterogeneous system consisting of multiple synthetic aperture radar satellites was constructed, and the orbital formation of the heterogeneous system was designed. A differential deformation error sensitivity model for the alien system is established to identify and quantify the main error sources affecting the accuracy of deformation measurement. Based on the aforementioned error sensitivity model, the key system errors are accurately estimated and compensated. A deformation model of an alien differential system after error compensation is established and solved to obtain surface deformation information.

2. The alien differential interferometry method according to claim 1, characterized in that, The same-origin design principle includes: the payload system, operating parameters, repeating orbit positions, repeating perspectives, repeating operating modes, and repeating wavelet parameters of all satellites within the heterogeneous system are kept consistent. The ground processing systems of all satellites within the alien system are also configured to process data from any satellite and support the same imaging modes, including but not limited to strip mode, spotlight mode, or scan mode.

3. The alien differential interferometry method according to claim 1, characterized in that, The orbital formation design includes: adopting a follow-fly formation configuration so that all satellites in the alien system operate on the same strict return orbit, and shortening the revisit period of a single satellite to one-Nth of the original through the design of orbital phase intervals, where N is the number of satellites.

4. The alien differential interferometry method according to claim 3, characterized in that, When the alien system consists of two satellites, the orbital phase interval between the two satellites is 180 degrees; When the alien system consists of four satellites, the orbital phases of the four satellites are evenly spaced at 90 degrees.

5. The alien differential interferometry method according to claim 1, characterized in that, The establishment of the alien differential deformation error sensitivity model includes: First, we establish the phase deformation equations for the absolute interference phase of the alien star, as follows: In the formula, The Doppler center frequency of the main star and These represent the position and velocity vectors of the primary star, respectively. and These are the observation times for alien planets. For the target position vector, For alien baseline vectors, This is an absolute interference phase of aliens. For radar wavelength, It is the Earth's equatorial radius. It is the ground elevation. The Earth's oblateness factor, R1 represents the slant range, where R1 is the deformation component along the radar line of sight. Then, based on the equations, the main error sources affecting the accuracy of deformation measurement were identified, including: the orbital positioning error of the primary star. Speed ​​error The radar system's own slant range measurement error Interferometric baseline error and elevation errors of external reference data ; Finally, by taking partial derivatives of the phase deformation equations with respect to each error variable, a sensitivity equation matrix model for the error source is established: Where F is the error source for each term. For deformation measurement accuracy The transfer function.

6. The differential interferometry method for alien celestial bodies according to claim 1, characterized in that, The accurate estimation and compensation of key system errors includes: During the field calibration phase, ground control points with known precise coordinates are used to perform precise parameter estimation of the interferometric phase error and baseline vector error. The calibrated interferometric phase error and baseline vector error are then used to compensate for the subsequently measured absolute interferometric phase and interferometric baseline, respectively, in order to optimize the on-board parameters.

7. The alien differential interferometry method according to claim 1, characterized in that, Establishing and solving the deformation model of the alien differential system includes: Phase obtained from observations of the primary star over the same region Phase obtained from observations of the region after a revisit cycle of the star. Calculate the absolute interference phase of alien stars The formulas are as follows: in, R 1 and R 2 represents the slant distance between the primary star and the secondary star. λ Represents the radar wavelength; The change in interference phase caused by deformation and r is directly proportional, as shown in the following formula: Among them, the surface deformation and displacement of the primary and secondary star systems during the two observation periods are: d, the displacement projected onto the satellite line of sight to the LOS deformation is r; Considering the deformation phase caused by elevation error, it is: in, For elevation error, h amb Elevation ambiguity; The interferometric deformation phase model of the alien system is: in, This is the downward viewpoint, and B⊥ is the vertical baseline.

8. A differential interferometry system for extraterrestrial objects, characterized in that, include: Module M1: Following the principle of homogeneous design, a heterogeneous system consisting of multiple synthetic aperture radar satellites was constructed; Module M2: Designs orbital formations for the alien system; Module M3: Establish a differential deformation error sensitivity model for the alien system to identify and quantify the main error sources affecting the accuracy of deformation measurement; Module M4: Based on the aforementioned error sensitivity model, accurately estimate and compensate for key system errors; Module M5: Establishes and solves the deformation model of the alien differential system after error compensation, thereby obtaining surface deformation information.

9. The alien differential interferometry system according to claim 8, characterized in that, The same-origin design principle includes: the payload system, operating parameters, repeating orbit positions, repeating perspectives, repeating operating modes, and repeating wavelet parameters of all satellites within the heterogeneous system are kept consistent. The ground processing systems of all satellites within the alien system are also configured to process data from any satellite and support the same imaging modes, including but not limited to strip mode, spotlight mode, or scan mode.

10. The alien differential interferometry system according to claim 8, characterized in that, The orbital formation design includes: adopting a follow-fly formation configuration so that all satellites in the alien system operate on the same strict return orbit, and shortening the revisit period of a single satellite to one-Nth of the original through the design of orbital phase intervals, where N is the number of satellites; When the alien system consists of two satellites, the orbital phase interval between the two satellites is 180 degrees; When the alien system consists of four satellites, the orbital phases of the four satellites are evenly spaced at 90 degrees.

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