Overall design method and system for double-satellite double-frequency-point InSAR (Interferometric Synthetic Aperture Radar) satellite system

Abstract

The invention provides an overall design method and system for a double-satellite double-frequency-point InSAR satellite system. The overall design method comprises the steps that the specification of a surveying and mapping product of the double-satellite double-frequency-point InSAR satellite system is determined; determining a target positioning equation of the double-satellite double-frequency-point InSAR satellite system; determining a resolving strategy of the absolute phase of the double-satellite double-frequency-point InSAR satellite system; designing double frequency points and working bandwidth of the SAR of the satellite system; distributing surveying and mapping indexes of the double-satellite double-frequency-point InSAR satellite system; designing a dual-frequency cooperative working mode of the SAR system; and designing an on-orbit working process of the double-satellite double-frequency-point InSAR satellite system. Through double-frequency cooperative imaging and full-link index distribution design under double-satellite formation, the problems of dependence of absolute phase ambiguity of traditional InSAR surveying and mapping calculation on ground control points and time decoherence of heavy-orbit interference are solved, and single-flight-pass, high-precision and uncontrolled global topographic surveying and mapping are realized. The method has the technical effects of greatly improving the self-positioning capability of the system, the surveying and mapping product quality and the development reliability.

Description

Technical Field

[0001] This invention relates to the field of satellite overall design, and more specifically, to an overall design method and system for a dual-satellite dual-frequency InSAR satellite system. Background Technology

[0002] Interferometric Synthetic Aperture Radar (InSAR) is an important remote sensing method for acquiring high-precision ground elevation models (DEMs). It utilizes two SAR antennas distributed along the vertical flight direction to observe the same area from different perspectives. The two complex SAR images are then interferometrically processed to calculate the slant range difference between the phase centers of the primary and secondary radar antennas and the target, thereby obtaining the DEM of the observed area. Figure 2 As shown, the distributed satellite InSAR system mounts two SAR units on two satellites flying in formation to observe the Earth simultaneously. It can overcome the problems of temporal decorrelation and low baseline accuracy faced by repeated pass-through InSAR, and can obtain high-precision DEMs.

[0003] Traditional InSAR mapping satellite systems can only rely on ground control data to resolve absolute interferometric phase ambiguity. The proposed InSAR dual-frequency point, same-viewpoint, same-area, and same-time imaging mapping method solves the engineering problem that InSAR mapping satellite systems can only rely on ground control data to resolve absolute interferometric phase ambiguity.

[0004] Patent CN114594473 discloses a method, apparatus, and device for resolving absolute phase difference ambiguity in dual-frequency interferometric SAR. This patent mainly focuses on the dual-frequency point deambiguity technology itself, which is insufficient to support the overall design of a satellite system. The overall satellite system design method proposed in this invention is obviously more engineering-operable. Secondly, this invention derives the target positioning equation of a dual-satellite dual-frequency point InSAR satellite system through a more rigorous process, which can more accurately integrate the dual-satellite dual-frequency point deambiguity technology into the overall satellite design. It is directly related to the satellite performance indicators and can directly guide the overall design of a dual-satellite dual-frequency point InSAR satellite system, making it more engineering-feasible.

[0005] The patent with publication number CN112526518B discloses a distributed InSAR satellite global seamless mapping design method and system. This patent mainly solves the problem of single-strip global seamless mapping, which is significantly different from the overall design problem of dual-satellite dual-frequency InSAR satellite system that this invention mainly solves in terms of application direction, applicable scope and technical approach.

[0006] The patent with publication number CN115113204A discloses a method for implementing spaceborne InSAR with distributed satellite dual-band separate transmission. However, the dual-frequency, dual-satellite InSAR working mode proposed in this patent is mainly aimed at improving the InSAR mapping accuracy of the satellite system rather than solving the engineering design problem of de-ambiguity, which is significantly different from the present invention in terms of application direction and technical approach.

[0007] The patent with publication number CN112379377B discloses a method and system for optimizing SAR mission planning in distributed InSAR satellite long strip mapping. However, this patent mainly addresses the problem of single strip mission planning and optimization parameter selection, which is significantly different from the present invention in terms of application direction, scope of application, and technical approach.

[0008] The patent with publication number CN112526518B discloses a distributed InSAR satellite global seamless mapping design method and system, but this patent mainly solves the problem of single-strip global seamless mapping, which is significantly different from the present invention in terms of application direction, scope of application and technical approach.

[0009] The patent with publication number CN110907932B discloses a method and system for analyzing factors affecting the accuracy of distributed InSAR satellite altimetry. This invention is the first to propose a mathematical expression for a dual-satellite dual-frequency InSAR altimetry model, while this patent mainly addresses the problem of analyzing factors affecting the accuracy of dual-satellite single-frequency InSAR altimetry and system design, showing a significant difference in technical approaches.

[0010] In summary, given the problems of the existing technologies, researching a general design method and system for a dual-satellite dual-frequency InSAR satellite system has become a critical task that urgently needs to be addressed. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the purpose of this invention is to provide a general design method and system for a dual-satellite dual-frequency InSAR satellite system.

[0012] The present invention provides a general design method for a dual-satellite dual-frequency InSAR satellite system, comprising the following steps: Step S1, defining the mapping product specifications of the dual-satellite dual-frequency InSAR satellite system; Step S2, determining the target positioning equation of the dual-satellite dual-frequency InSAR satellite system; Step S3, determining the absolute phase calculation strategy of the dual-satellite dual-frequency InSAR satellite system; Step S4, designing the SAR dual frequencies and operating bandwidth of the satellite system; Step S5, allocating mapping indicators for the dual-satellite dual-frequency InSAR satellite system; Step S6, designing the dual-frequency cooperative working mode of the SAR system; Step S7, designing the on-orbit workflow of the dual-satellite dual-frequency InSAR satellite system.

[0013] Preferably, determining the mapping product specifications of the dual-satellite dual-frequency InSAR satellite system includes: determining the relative elevation accuracy and absolute elevation accuracy indicators of the dual-satellite dual-frequency InSAR satellite system according to the accuracy requirements of 1:5000, 1:10000, 1:25000, 1:50000, and 1:100000 specified in the digital elevation model standard.

[0014] Preferably, the determination of the target positioning equation for the dual-satellite dual-frequency InSAR satellite system includes: the target positioning equation is a joint set of equations combining the orbital states of the two satellites, the baseline vector, and the dual-frequency interferometric phase:

[0015] in, For the position vector of the observed target point, and This represents the position vector and velocity vector of the primary star at the corresponding moment. The instantaneous baseline vector of the primary and secondary radars. and These are the two operating frequency points of the radar. Main satellite radar slant range The center frequency of the Doppler wave. and They are respectively Frequency point primary and secondary star interference time, for Frequency point auxiliary star interference time, At the speed of light, and These are the two-frequency point interferometric unwrapping phases, and These are the absolute ambiguity numbers of the two-frequency interferogram.

[0016] Preferably, the strategy for determining the absolute phase of a dual-satellite, dual-frequency InSAR satellite system includes: calculating the ambiguity heights corresponding to the first and second frequencies based on the observation geometric parameters of the dual-satellite system. and The formula for calculating the fuzzy height is:

[0017] in, From the radar side perspective, For wavelength, The distance from the target point to the SAR antenna. The effective vertical baseline length; based on dual-frequency data acquired from the same ground point, an absolute elevation equation is constructed, assuming wavelength... and The absolute phase ambiguity numbers of the corresponding unwrapped interferometric phase diagrams are respectively and ,but and The following relationship must be satisfied:

[0018] in, For frequency The elevation corresponding to the unwrapping phase difference. For frequency The corresponding fuzzy height, For ground point elevation; and Perform a two-dimensional traversal search and select the appropriate option. and Equal Combine the data to determine the absolute phase ambiguity number of the unwrapped interference phase diagram.

[0019] Preferably, the design of the satellite system's SAR dual-frequency points and operating bandwidth includes: a mapping method utilizing InSAR system dual-satellite dual-frequency points, same viewing angle, same area, and same time imaging, using the dominant frequency at the beginning and end of the imaging process respectively. and auxiliary frequency Dual-frequency imaging is performed at two frequencies to form an interference image pair at the two frequencies; the dominant frequency is configured. The frequency points are kept consistent with those of the interferometric mapping mission, and the same operating parameters are set to ensure seamless connection between satellite data acquisition and single-frequency interferometric data acquisition imaging. The difference between the two frequency points is determined based on the frequency doubling capability of the SAR payload reference frequency and the folding ambiguity number corresponding to the frequency difference. The SAR signal bandwidth B is calculated using the following formula according to the mapping image resolution requirements:

[0020] in, For image resolution, At the speed of light, Let B be the SAR incident angle; based on the calculated signal bandwidth B and the available operating frequency bands of the SAR, select two mutually non-interfering SAR operating frequency points. And satisfy the following relationship:

[0021] Preferably, the allocation of mapping indicators for the dual-satellite dual-frequency InSAR satellite system includes: analyzing the elevation error using a bistatic InSAR satellite altimetry accuracy analysis method based on positioning equations; and allocating the elevation error indicators to satellite orbit determination accuracy, velocity measurement accuracy, SAR slant range accuracy, and baseline measurement accuracy satellite indicators.

[0022] Preferably, the dual-frequency cooperative operating mode of the SAR system includes: configuring the two satellites to operate in a fly-around formation state; and controlling satellite A and satellite B to alternately use frequency points. Transmit radar waves towards the target strip area and control satellite A to receive dual-frequency signals. While receiving echo data, satellite B was also receiving data from both frequencies. The echo data; four ground elevation model data samples of the same target area were obtained through a single-pass flight of the formation satellites. The data samples include: frequency points DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point The DEM data and frequency points were acquired by satellite B and simultaneously received by satellites A and B. The DEM data was launched by satellite B and simultaneously received by satellites A and B.

[0023] Preferably, the on-orbit workflow of the dual-satellite dual-frequency InSAR satellite system includes: the satellite system completing the dual-satellite formation configuration design and dual-satellite dual-frequency wavefront design according to mission requirements; the telemetry, tracking, and command (TT&C) system calculating the overpass time of the two satellites over the same target area based on the dual-satellite orbit prediction results, and calculating the overpass time of the two satellites over the ground data receiving station after imaging; the operation and control system calculating the dual-satellite dual-frequency SAR operating parameters based on the orbit prediction results, compiling payload command packages, and uploading them to the satellite via the satellite-to-ground link through the TT&C system, wherein the payload command packages include generating SAR command packages and generating data transmission command packages; the satellite system controlling the SAR payload to start imaging during the target overpass time and controlling the data transmission subsystem to transmit data to the ground during the ground data receiving station overpass time according to the payload command packages; and the ground processing system receiving the data transmitted from the satellite, sequentially performing SAR imaging processing and InSAR processing on the transmitted data, and finally obtaining mapping products.

[0024] Preferably, the satellite system controls the SAR payload to start imaging during the target overhead period according to the payload command packet, and controls the data transmission subsystem to perform ground data transmission during the ground data receiving station overhead period. This includes: the SAR subsystem performing focused imaging of the target when it passes over the target area according to the SAR command packet; and the data transmission subsystem recording SAR imaging data during SAR imaging and performing ground data transmission according to the data transmission command packet when it passes over the ground data receiving station.

[0025] This invention also provides a general design system for a dual-satellite dual-frequency INSAR satellite system. This system can be implemented by executing the steps of the general design method for a dual-satellite dual-frequency INSAR satellite system. That is, those skilled in the art can understand the general design method for a dual-satellite dual-frequency INSAR satellite system as a preferred embodiment of the general design system. The system includes: Module M1 determines the specifications of mapping products for the dual-satellite, dual-frequency InSAR satellite system; Module M2 determines the target positioning equation for the dual-satellite, dual-frequency InSAR satellite system; Module M3 determines the solution strategy for the absolute phase of a dual-satellite, dual-frequency InSAR satellite system; Module M4 is designed to define the dual-frequency points and operating bandwidth of the satellite system's SAR. Module M5, allocation of mapping indicators for a dual-satellite, dual-frequency InSAR satellite system; Module M6 is designed for a dual-frequency cooperative working mode of the SAR system. Module M7 designs the on-orbit workflow of a dual-satellite, dual-frequency InSAR satellite system.

[0026] Compared with existing technologies, the present invention has the following beneficial effects: By introducing a dual-frequency design and utilizing the principle of dual-frequency interferometric phase difference and remainder theorem, the present invention directly calculates the absolute phase ambiguity number mathematically, expanding the unambiguous elevation range. This enables the system to independently acquire high-precision absolute elevation data in areas where ground control points cannot be deployed, significantly improving the system's global mapping capabilities and autonomy. Furthermore, through the cooperative working mode of alternating transmission and simultaneous reception, and multi-view, multi-frequency redundant data observation, the present invention not only improves the flexibility of effective baseline combinations but also further reduces random noise through data fusion, thereby improving the reliability of the final mapping products. Attached Figure Description

[0027] 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 general design method for a dual-satellite, dual-frequency INSAR satellite system provided by this invention.

[0028] Figure 2 This is a schematic diagram illustrating the distributed InSAR satellite mapping principle of the present invention.

[0029] Figure 3 This is a schematic diagram illustrating the relationship between dual-frequency deambiguity and interferometric altimetry in this invention.

[0030] Figure 4This is a schematic diagram of the dual-frequency working mode of the present invention.

[0031] Figure 5 This is a flowchart illustrating the on-orbit operation of the dual-satellite dual-frequency InSAR satellite system of the present invention. Detailed Implementation

[0032] 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.

[0033] Figure 1 A flowchart of an overall design method for a dual-satellite, dual-frequency INSAR satellite system provided by this invention is shown below. Figure 1 As shown, it includes: Step 1: Determine the specifications of InSAR satellite system mapping products.

[0034] According to the "Surveying and Mapping Industry Standard of the People's Republic of China (CH / T9009.2-2021) Basic Geographic Information Digital Results 1:5000, 1:10000, 1:25000, 1:50000, 1:100000 Digital Elevation Models (Effective 2021-07-01)" issued by the State Bureau of Surveying and Mapping of China, the specifications of distributed InSAR satellite system surveying and mapping products are designed. In this embodiment, the 1:50000 scale digital elevation model product is taken as an example, and the design method for other specifications is the same; the main indicators of the 1:50000 scale digital elevation model product include: (a) grid size: 25 meters, (b) elevation error (level 1): 3 meters for flat land, 5 meters for hilly land, 8 meters for mountainous land, and 14 meters for high mountainous land.

[0035] Step 2: Establish the dual-satellite dual-frequency InSAR satellite target positioning equation.

[0036] The mathematical expression for the dual-satellite, dual-frequency InSAR altimetry model is as follows:

[0037] in, For the position vector of the observed target point, and This represents the position vector and velocity vector of the primary star at the corresponding moment. The instantaneous baseline vector of the primary and secondary radars. and These are the two operating frequency points of the radar. Main satellite radar slant range The center frequency of the Doppler wave. and They are respectively Frequency point primary and secondary star interference time, for Frequency point auxiliary star interference time, At the speed of light, and These are the two-frequency point interferometric unwrapping phases, and These are the absolute ambiguity numbers of the two-frequency interferogram.

[0038] Step 3: Determine the absolute phase of the dual-satellite dual-frequency InSAR satellite.

[0039] A schematic diagram illustrating the relationship between dual-frequency deambiguity and interferometric altimetry is shown below. Figure 3 As shown, by performing dual-frequency interferometry processing on the first and last two main and auxiliary dual-frequency ground echo data, the absolute ambiguity in the phase difference of the main frequency interferometry can be resolved according to the remainder theorem. The problem of determining fuzzy numbers involves the principle of absolute fuzzy solution and fuzzy height. The calculation formula is

[0040] in, From the radar side perspective, For wavelength, The distance from the target point to the SAR antenna. The effective vertical baseline length; based on dual-frequency data acquired from the same ground point, an absolute elevation equation is constructed, assuming wavelength... and The absolute phase ambiguity numbers of the corresponding unwrapped interferometric phase diagrams are respectively and ,but and The following relationship must be satisfied:

[0041] in, For frequency The elevation corresponding to the unwrapping phase difference. For frequency The corresponding fuzzy height, For ground point elevation; and Perform a two-dimensional traversal search and select the appropriate option. and Equal Combine the data to determine the absolute phase ambiguity number of the unwrapped interference phase diagram.

[0042] Step 4: Design the satellite system's SAR dual-frequency points and operating bandwidth.

[0043] Specifically, this method utilizes the dual-satellite, dual-frequency, same-viewpoint, same-area, and same-time imaging technique of the InSAR system to resolve the dependence of microwave mapping systems on absolute ambiguity in the interferometric phase resolution of ground control data. This is achieved using the dominant frequency of the X-band InSAR satellite system. Taking signal bandwidth B as an example, the main frequency is used at the beginning and end of the imaging process. and auxiliary frequency Dual-frequency imaging is performed at two frequencies to form an interferometric image pair. The difference between the two frequencies is determined based on the cascading capability of the SAR payload's reference frequency and the folding ambiguity number corresponding to the frequency difference. The dominant frequency is... The frequency points are consistent with those of the interferometric mapping mission, and the operating parameters are also set identically. Furthermore, during satellite data acquisition, there is seamless integration with single-frequency interferometric data acquisition and imaging. For the mission requirements of distributed InSAR satellites, the SAR signal bandwidth B is calculated using the following formula based on the mapping image resolution requirements: To affect resolution, At the speed of light, The incident angle for the SAR is [value].

[0044]

[0045] Based on the calculated signal bandwidth B and the available operating frequency bands for SAR, two mutually non-interfering SAR operating frequency points are selected. , The following requirements must be met:

[0046] Step 5: Complete the allocation of satellite system mapping indicators.

[0047] Specifically, the analysis was conducted using a bistatic InSAR satellite altimetry accuracy analysis method based on positioning equations, and the elevation error index was allocated to satellite indicators such as satellite orbit determination accuracy, velocity measurement accuracy, SAR slant range accuracy, and baseline measurement accuracy.

[0048] Primary satellite positioning error: As can be derived from the target positioning equation, The transfer function of the orbit determination error at the master star interferometry time (i.e., time t1) to the InSAR target positioning error is:

[0049] in, , The transformation matrix is ​​defined as follows:

[0050]

[0051] The coordinate system is defined as the WGS84 coordinate system, and the position vector of the ground target is... ( The position and velocity vector of the main antenna phase center at azimuth time t1 are: ( ), ( The position vector at azimuth time t2 is ( The position and velocity vector of the auxiliary antenna phase center at azimuth time t2 are: ( ), ( ); The baseline vector of the primary and secondary radars at azimuth time t2.

[0052] Primary star velocity measurement error: The transfer function of the primary star velocity measurement error to the InSAR target positioning error at the primary star interferometry time (i.e., time t1) is:

[0053] Slope distance measurement error: If the slant range from the main antenna phase center to the target is , then the slant range measurement error is... The transfer function for InSAR target localization error is:

[0054] Baseline measurement error: The transfer function of the instantaneous baseline error of the primary and secondary radars at azimuth time t2 to the InSAR target localization error is:

[0055] Interferometric phase error: The main sources of error in distributed satellite InSAR interferometric phase analysis include decoherence, phase synchronization error, intra-phase calibration error, and ground processing error. This can be derived from the target positioning equation. If the interferometric phase of the primary and secondary SAR images is considered, then the interferometric phase error... The impact on target positioning accuracy is as follows:

[0056] In summary, the target positioning error of a distributed satellite InSAR system can be approximated as:

[0057] In this embodiment, the product requirement is a 1:50,000 scale digital elevation model, and the satellite orbit determination accuracy should be no less than 5 centimeters (1 The speed measurement accuracy should be no less than 3 mm / s (1) ), the SAR slant range accuracy should be no less than 1 meter (1 The baseline measurement accuracy should be no less than 3 mm (1) ).

[0058] Step 6: Design the dual-frequency operating mode of the SAR system.

[0059] A schematic diagram of the dual-frequency working mode is shown below. Figure 4 As shown, specifically, the two satellites operate in a fly-around formation, with satellites A and B alternating frequencies. , Radar waves are transmitted toward the target strip area, and satellite A receives them at dual frequencies. , While receiving echo data, satellite B is also receiving dual-frequency data. , The echo data. Therefore, a single flight of the formation satellites can acquire four ground elevation model (DEM) data samples of the same target area, including frequency points. DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point DEM data transmitted by satellite B and simultaneously received by satellites A and B, frequency points The DEM data was launched by satellite B and simultaneously received by satellites A and B.

[0060] Step 7: Design the on-orbit workflow of the distributed dual-satellite dual-frequency InSAR satellite system.

[0061] like Figure 5 As shown, the satellite system, according to mission requirements, completes the design of the InSAR satellite system's dual-satellite formation configuration and the dual-satellite dual-frequency wavefront design; the telemetry, tracking, and command (TT&C) system calculates the overpass time of the two satellites over the same target area based on the dual-satellite orbit prediction results, and calculates the overpass time of the two satellites over the ground data receiving station after imaging; the operation and control system calculates the dual-satellite dual-frequency SAR operating parameters based on the orbit prediction results, compiles payload command packages, and hands them over to the TT&C system for uploading to the satellite via the satellite-to-ground link. The payload command packages include SAR generation command packages and data transmission command packages; according to the payload command packages, the satellite system controls the SAR payload to start imaging during the target overpass time, and controls the data transmission subsystem to transmit data to the ground during the ground data receiving station overpass time; the ground processing system receives the data transmitted from the satellite, performs SAR imaging processing and InSAR processing on the transmitted data in sequence, and finally obtains the mapping products.

[0062] This invention also provides a general design system for a dual-satellite dual-frequency INSAR satellite system. This system can be implemented by executing the steps of the general design method for a dual-satellite dual-frequency INSAR satellite system. That is, those skilled in the art can understand the general design method for a dual-satellite dual-frequency INSAR satellite system as a preferred embodiment of the general design system. The system includes: Module M1 is used to determine the specifications of mapping products for a dual-satellite, dual-frequency InSAR satellite system; Module M2 is used to determine the target positioning equation for a dual-satellite, dual-frequency InSAR satellite system; Module M3 is used to determine the solution strategy for the absolute phase of a dual-satellite, dual-frequency InSAR satellite system; Module M4 is used to design the SAR dual-frequency points and operating bandwidth of the satellite system; Module M5 is used for the allocation of mapping indicators for a dual-satellite, dual-frequency InSAR satellite system. Module M6 is used to design the dual-frequency cooperative working mode of the SAR system; Module M7 is used to design the on-orbit workflow of a dual-satellite, dual-frequency InSAR satellite system.

[0063] 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.

[0064] 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 general design method for a dual-satellite, dual-frequency InSAR satellite system, characterized in that, include: Step S1: Determine the specifications of the mapping products for the dual-satellite dual-frequency InSAR satellite system; Step S2: Determine the target positioning equation for the dual-satellite dual-frequency InSAR satellite system; Step S3: Determine the solution strategy for the absolute phase of the dual-satellite dual-frequency InSAR satellite system; Step S4: Design the satellite system's SAR dual-frequency points and operating bandwidth; Step S5: Assignment of mapping indicators for the dual-satellite, dual-frequency InSAR satellite system; Step S6: Design the dual-frequency cooperative working mode of the SAR system; Step S7: Design the on-orbit workflow of the dual-satellite dual-frequency InSAR satellite system.

2. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The determination of the mapping product specifications for the dual-satellite, dual-frequency InSAR satellite system includes: Based on the accuracy requirements of 1:5000, 1:10000, 1:25000, 1:50000, and 1:100000 specified in the digital elevation model standard, the relative elevation accuracy and absolute elevation accuracy indicators of the dual-satellite dual-frequency InSAR satellite system are determined.

3. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The determination of the target positioning equation for the dual-satellite, dual-frequency InSAR satellite system includes: The target positioning equation is a set of joint equations combining the binary star orbital states, baseline vectors, and dual-frequency interferometric phases: in, For the position vector of the observed target point, and This represents the position vector and velocity vector of the primary star at the corresponding moment. The instantaneous baseline vector of the primary and secondary radars. and These are the two operating frequency points of the radar. Main satellite radar slant range The center frequency of the Doppler wave. and They are respectively Frequency point primary and secondary star interference time, for Frequency point auxiliary star interference time, At the speed of light, and These are the two-frequency point interferometric unwrapping phases, and These are the absolute ambiguity numbers of the two-frequency interferogram.

4. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The strategy for determining the absolute phase of a dual-satellite, dual-frequency InSAR satellite system includes: Based on the observed geometric parameters of the binary system, the ambiguity heights corresponding to the first and second frequencies are calculated respectively. and The formula for calculating the fuzzy height is: in, From the radar side perspective, For wavelength, The distance from the target point to the SAR antenna. The effective vertical baseline length; Based on dual-frequency data acquired from the same ground point, an absolute elevation equation is constructed, assuming wavelength... and The absolute phase ambiguity numbers of the corresponding unwrapped interferometric phase diagrams are respectively and ,but and The following relationship must be satisfied: in, For frequency The elevation corresponding to the unwrapping phase difference. For frequency The corresponding fuzzy height, Elevation of ground point; right and Perform a two-dimensional traversal search and select the appropriate option. and Equal Combine the data to determine the absolute phase ambiguity number of the unwrapped interference phase diagram.

5. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The design of the satellite system's SAR dual-frequency points and operating bandwidth includes: Mapping methods utilizing InSAR systems with dual satellites, dual frequencies, same viewing angle, same region, and same time imaging, employing the dominant frequency at the beginning and end of the imaging process respectively. and auxiliary frequency Dual-frequency imaging is performed at two frequency points to form an interference image pair at the two frequency points; Configure main frequency The frequency points are kept consistent with those of the interferometric mapping mission, and the same working parameters are set so that the satellite data acquisition is seamlessly connected with the single-frequency interferometric data acquisition imaging. The difference between the two frequency points is determined based on the frequency doubling capability of the SAR payload reference frequency and the folding ambiguity number corresponding to the frequency difference. Based on the resolution requirements of the mapping image, the SAR signal bandwidth B is calculated using the following formula: in, For image resolution, At the speed of light, The SAR incident angle; Based on the calculated signal bandwidth B and the available operating frequency bands of SAR, two mutually non-interfering SAR operating frequency points are selected. And satisfy the following relationship: 。 6. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The mapping index allocation for the dual-satellite, dual-frequency InSAR satellite system includes: The analysis was performed using a bistatic InSAR satellite altimetry precision analysis method based on the positioning equation. The elevation error index is allocated to satellite indicators such as satellite orbit determination accuracy, velocity measurement accuracy, SAR slant range accuracy, and baseline measurement accuracy.

7. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The design of the SAR system's dual-frequency cooperative operating mode includes: The two satellites are configured to operate in a flying formation configuration. Control satellites A and B to alternately use frequency points Transmit radar waves towards the target strip area and control satellite A to receive dual-frequency signals. While receiving echo data, satellite B was also receiving data from both frequencies. Echo data; Four ground elevation model data samples of the same target area were acquired by a single-pass flight of a formation of satellites. The data samples include: frequency points DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point DEM data transmitted by satellite A and simultaneously received by satellites A and B, frequency point The DEM data and frequency points were acquired by satellite B and simultaneously received by satellites A and B. The DEM data was launched by satellite B and simultaneously received by satellites A and B.

8. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 1, characterized in that, The on-orbit workflow of the designed dual-satellite dual-frequency InSAR satellite system includes: According to mission requirements, the satellite system completed the design of the InSAR satellite system's dual-satellite formation configuration and the dual-satellite dual-frequency point wave position design; The telemetry, tracking, and command system calculates the overhead time of the two satellites over the same target area based on the orbit prediction results of the two satellites, and also calculates the overhead time of the two satellites over the ground data receiving station after imaging. The operation and control system calculates the dual-satellite dual-frequency SAR operating parameters based on the orbit prediction results, compiles the payload command package, and hands it over to the telemetry, tracking and command system for uploading to the satellite via the satellite-to-ground link. The payload command package includes a SAR generation command package and a data transmission command package. According to the payload command package, the satellite system controls the SAR payload to start imaging during the target overhead period, and controls the data transmission subsystem to transmit data to the ground during the ground data receiving station overhead period; The ground processing system receives data transmitted from the satellite and performs SAR imaging and InSAR processing on the transmitted data in sequence to finally obtain mapping products.

9. The overall design method for a dual-satellite, dual-frequency InSAR satellite system according to claim 8, characterized in that, The satellite system, based on the payload command packet, controls the SAR payload to activate and image during the target overhead transit period, and controls the data transmission subsystem to perform ground data transmission during the ground data receiving station overhead transit period, including: The SAR subsystem performs focused imaging of the target when passing over the target area, based on the SAR command packet. The data transmission subsystem records SAR imaging data during SAR imaging and transmits data to the ground according to the data transmission command packet when passing over the overhead ground data receiving station.

10. A general design system for a dual-satellite, dual-frequency InSAR satellite system, characterized in that, include: Module M1 determines the specifications of mapping products for the dual-satellite, dual-frequency InSAR satellite system; Module M2 determines the target positioning equation for the dual-satellite, dual-frequency InSAR satellite system; Module M3 determines the solution strategy for the absolute phase of a dual-satellite, dual-frequency InSAR satellite system; Module M4 is designed to define the dual-frequency points and operating bandwidth of the satellite system's SAR. Module M5, allocation of mapping indicators for a dual-satellite, dual-frequency InSAR satellite system; Module M6 is designed for a dual-frequency cooperative working mode of the SAR system. Module M7 designs the on-orbit workflow of a dual-satellite, dual-frequency InSAR satellite system.

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