Multi-frequency multi-base InSAR satellite system engineering design method and system

Abstract

The invention provides a multi-frequency multi-base InSAR satellite system engineering design method. The method comprises the following steps: acquiring a multi-frequency multi-base InSAR satellite surveying and mapping working mode; the formation configuration of a plurality of satellites is obtained, and the space baseline requirement is met; working signal bandwidth between any two SAR is obtained, and the requirements for resolution, bandwidth and positioning precision are met; obtaining different working frequency points of each SAR and a working time sequence and a working wave position of frequency division emission; and after all parameters are confirmed, on-orbit work is executed. The technical problem that in the prior art, high-precision surveying and mapping engineering design of a multi-frequency multi-base InSAR system is difficult to achieve is solved.

Description

Technical Field

[0001] This invention relates to the field of aerospace systems technology, specifically to an engineering design method and system for a multi-frequency, multi-base 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 7 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] The mapping accuracy of distributed InSAR satellites is a core indicator of system design, directly impacting the satellite's design life, production costs, and the value of its image products. Therefore, improving the mapping accuracy of distributed InSAR satellites has become a core task in satellite system design. With the rapid development of spaceborne InSAR technology, traditional single-frequency, dual-satellite InSAR mapping systems can no longer meet the increasingly urgent demands of users for higher mapping accuracy. Therefore, developing multi-frequency, multi-base InSAR satellite systems and improving InSAR mapping accuracy urgently requires focused research.

[0004] Patent document CN112379377B discloses a "Distributed InSAR Satellite Long Strip Mapping Optimization SAR Mission Planning Method and System," authorized and published on August 12, 2022. This invention primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, while this patent mainly addresses the problem of single-strip mission planning and optimization parameter selection. There are significant differences in their application direction, applicable scope, and technical approach.

[0005] Patent document CN115113204A discloses a "Method for Implementing Spaceborne InSAR with Distributed Satellite Dual-Band Separate Transmission," authorized and published on September 27, 2022. This invention primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, while this patent mainly addresses the design problem of dual-frequency, dual-satellite InSAR operating modes; the technical approaches are significantly different.

[0006] Patent document CN112526518B discloses a "Distributed InSAR Satellite Global Seamless Mapping Design Method and System," with an authorization publication date of October 25, 2022. This invention primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, while this patent mainly addresses the problem of single-strip global seamless mapping. There are significant differences in their application direction, scope of application, and technical approach.

[0007] Patent document CN110907932B discloses a "Method and System for Analyzing Factors Affecting the Accuracy of Distributed InSAR Satellite Altimetry," with an authorization publication date of March 18, 2022. While the present invention primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, this patent mainly addresses the analysis of factors affecting the accuracy of InSAR altimetry and system design, showing significant differences in application direction, scope of application, and technical approach.

[0008] Patent document CN113311432B discloses "A Phase Estimation Method for InSAR Long and Short Baselines Fusion Based on Phase Derivative Variance," with an authorized publication date of January 13, 2023. This invention primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, while this patent mainly addresses the ground processing problem of InSAR long and short baseline fusion phase estimation. They differ significantly in application direction, scope of application, and technical approach.

[0009] Airborne Dual-Frequency Curve SAR System and Experiment, Radar Science and Technology, 202103. Main differences: This patent primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, introducing dual-frequency point technology mainly to acquire more mapping data samples. In contrast, this paper adopts a dual-frequency system primarily to obtain higher image resolution. There are significant differences in application direction, applicable scope, and technical approach.

[0010] Analysis of Altimetry Precision in Dual-Frequency Ping-Pong Mode of Spaceborne Distributed SAR, Journal of Geodesy and Cartography, 202405. Main differences: This patent primarily addresses the engineering design problem of improving the accuracy of multi-frequency, multi-satellite InSAR mapping, while this paper focuses on the quantitative analysis of improving the mapping performance of satellite systems using multiple test samples during the ground processing of satellite data. There are significant differences in application direction, applicable stage, and technical approach. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the purpose of this invention is to provide an engineering design method and system for multi-frequency, multi-base InSAR satellite systems.

[0012] According to one aspect of the present invention, an engineering design method for a multi-frequency, multi-base InSAR satellite system is provided, comprising the following steps: Working mode acquisition: Acquire multi-frequency, multi-base InSAR satellite mapping working modes; Formation configuration acquisition: Acquire the formation configuration of multiple satellites, wherein the formation configuration conforms to the spatial baseline requirements preset for multi-site InSAR satellite system mapping; Working signal bandwidth acquisition: Obtain the working signal bandwidth between any two SARs, where the working signal bandwidth meets the requirements of image resolution, strip observation band width and ground positioning accuracy; Operating frequency acquisition: Acquire the operating frequency of each SAR, where the operating frequency of each SAR is different; Operational timing acquisition: Obtain the operational timing of each SAR frequency division transmission; Working position acquisition: Acquire the working position for each SAR; On-orbit operation execution: After confirming and acquiring the working mode, formation configuration, working signal, working frequency, working timing, and working position, perform multi-frequency multi-baseband on-orbit operation.

[0013] Preferably, the working mode in the working mode acquisition step includes: At least three SARs operating at different frequencies sequentially transmit radar waves toward the same target strip; each SAR receives radar wave signals reflected by the same target strip transmitted by each SAR; multiple SAR-generated images are acquired; and multiple sets of DEM sample data are formed based on the acquired images.

[0014] Preferably, the operating signal bandwidth between any two SARs satisfies the following formula:

[0015] Where B is the signal bandwidth. Where c is the image resolution and c is the speed of light. The incident angle for the SAR is [value].

[0016] Preferably, the operating frequency of each SAR satisfies the following formula:

[0017]

[0018] in, , , For different SAR operating frequencies, n is a natural number greater than 2.

[0019] Preferably, the operating timing is as follows: each SAR simultaneously transmits radar waves and receives radar wave signals reflected by the target strip from all SARs, wherein the timing of individual SARs receiving radar wave signals at different operating frequencies is simultaneous.

[0020] Preferably, the working waveform acquisition step includes: Acquire system parameters, including image resolution, observation band width, orbit parameters, antenna aperture, operating mode, operating parameters, and beam pointing. The system parameters are analyzed based on performance indicators, including system sensitivity and ambiguity. The wave position planning was optimized based on the analysis results; Maintain consistency in pulse repetition frequency, number of sampling points, and signal bandwidth for each SAR; Acquire and analyze the spatial geometric relationships between SARs, and obtain the sampling start time of multiple SARs.

[0021] According to another aspect of the present invention, a multi-frequency, multi-base InSAR satellite system engineering design system is provided, comprising: Module M1: Used to acquire multi-frequency, multi-base InSAR satellite mapping working modes; Module M2: Used to acquire the formation configuration of multiple satellites, wherein the formation configuration conforms to the spatial baseline requirements preset for multi-static InSAR satellite system mapping; Module M3: Used to obtain the working signal bandwidth between any two SARs, wherein the working signal bandwidth meets the requirements of image resolution, strip observation band width and ground positioning accuracy; Module M4: Used to obtain the operating frequency of each SAR, where the operating frequency of each SAR is different; Module M5: Used to obtain the working timing of each SAR frequency division transmission; Module M6: Used to acquire the working waveforms for each SAR; Module M7: Used to perform multi-frequency, multi-baseband on-orbit operation after confirming and acquiring the operating mode, formation configuration, operating signal, operating frequency, operating timing, and operating position.

[0022] Preferably, the operating mode includes: At least three SARs operating at different frequencies sequentially transmit radar waves toward the same target strip; each SAR receives radar wave signals reflected by the same target strip transmitted by each SAR; multiple SAR-generated images are acquired; and multiple sets of DEM sample data are formed based on the acquired images.

[0023] Preferably, the operating signal bandwidth between any two SARs satisfies the following formula:

[0024] Where B is the signal bandwidth. Where c is the image resolution and c is the speed of light. The incident angle for the SAR is [value].

[0025] Preferably, the operating frequency of each SAR satisfies the following formula:

[0026]

[0027] in, , , For different SAR operating frequencies, n is a natural number greater than 2.

[0028] Preferably, the operating timing is as follows: each SAR simultaneously transmits radar waves and receives radar wave signals reflected by the target strip from all SARs, wherein the timing of individual SARs receiving radar wave signals at different operating frequencies is simultaneous.

[0029] Preferably, module M6 is further configured to: acquire system parameters, including image resolution, observation band width, orbital parameters, antenna aperture, operating mode, operating parameters, and beam pointing; analyze the system parameters based on performance indicators, including system sensitivity and ambiguity; optimize beam position planning based on the analysis results; maintain consistency in the pulse repetition frequency, number of sampling points, and signal bandwidth of each SAR; acquire and analyze the spatial geometric relationships between SARs, and acquire the sampling start time of multiple SARs.

[0030] Compared with the prior art, the present invention has the following beneficial effects: This invention designs a three-satellite formation configuration to create multiple spatial baselines and assigns three non-interfering operating frequencies to each of the three satellites. Combined with frequency-division transmission and synchronous reception, this ensures that each transmission generates two sets of interferometric pairs. Simultaneously, by rationally designing the SAR operating wavefront, it guarantees that the three satellites can illuminate the same ground strip at different frequencies. Based on these specific technical means, a single flyby can generate six independent interferometric pairs, thus producing six sets of independent DEM sample data, increasing data acquisition efficiency to six times that of traditional methods. This invention, through multi-frequency design, allows three satellites to observe the same area at different frequencies, thereby acquiring observation results of ground features under different electromagnetic responses. Through multi-base configuration, each frequency point can form two sets of independent interferometric pairs, ensuring the independence of the data. Based on cross-validation and fusion processing of the six sets of DEM samples, the impact of systematic errors and random noise is effectively reduced. Experimental results show that the relative mapping accuracy can reach 2.4 times the accuracy of a single set of DEM samples. This invention employs a collaborative design involving multiple frequencies, multiple baselines, and multiple wavebands. Even if data at a particular frequency or baseline is interfered with or degraded in quality, it can still be compensated for by other independently combined data, thereby significantly improving the system's data robustness and mapping reliability in complex terrain and strong interference environments. The satellite of this invention, through precise calculations, uses three non-overlapping operating frequencies, effectively avoiding signal crosstalk and interference caused by co-frequency observations, ensuring the distinguishability of received signals and the accuracy of interferometry processing. Attached Figure Description

[0031] 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 schematic diagram of the engineering design method for a multi-frequency, multi-base InSAR satellite system in this embodiment.

[0032] Figure 2 This is a schematic diagram of the mapping operation mode of the multi-frequency, multi-base InSAR satellite system in this embodiment.

[0033] Figure 3 This is a logical diagram illustrating the acquisition of multiple sets of DEM sample data under the working mode in this embodiment.

[0034] Figure 4 This is a schematic diagram of the formation configuration in this embodiment.

[0035] Figure 5 This is a schematic diagram of the working timing in this embodiment.

[0036] Figure 6 This is a schematic diagram of the working waveform in this embodiment.

[0037] Figure 7This is a schematic diagram of existing single-frequency dual-satellite mapping technology. Detailed Implementation

[0038] 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.

[0039] For ease of understanding, the terms or concepts involved in the methods provided in this application are explained below: (1) Interferometric Synthetic Aperture Radar (InSAR) A remote sensing method that uses the phase difference between two or more SAR images to obtain surface elevation information.

[0040] (2) Ground elevation model (DEM) It is a digital simulation of ground terrain (i.e., a digital representation of the surface morphology of terrain) achieved through limited terrain elevation data. It is a physical ground model that represents ground elevation in the form of an ordered numerical array. It is a branch of Digital Terrain Model (DTM), from which various other terrain feature values ​​can be derived.

[0041] (3) Synthetic Aperture Radar (SAR) An active imaging radar generates images by emitting microwaves and receiving echoes reflected from ground objects.

[0042] (4) Baseline This refers to the relative distance and direction between two satellites. The longer the baseline, the stronger the stereo measurement capability, but the more complex the data processing.

[0043] (5) Formation configuration The relative arrangement of satellites, such as in a triangle or V-shape, determines the baseline length and direction, and is a fundamental parameter for system design.

[0044] (6) Operating frequency The center frequency of the signals transmitted by each satellite radar.

[0045] (7) Signal bandwidth The wider the frequency range occupied by the radar signal, the higher the imaging resolution. The required bandwidth is determined by calculating the resolution requirements.

[0046] (8) Working wave position This refers to the pointing angle and beam coverage area of ​​each satellite radar antenna. It is necessary to ensure that all satellites illuminate the same ground strip in order to achieve superimposed interference.

[0047] (9) Swath A single satellite radar image covers a long strip of ground, tens to hundreds of kilometers wide. Multiple satellites must illuminate the same strip to ensure that the data can be fused.

[0048] The embodiments of this application can be applied to interferometric synthetic aperture radar. InSAR (In-Radar Radar System) acquires high-precision Digital Elevation Models (DEMs). When conducting surveying, InSAR uses the phase difference of radar signals to calculate the elevation information of the earth's surface. It can be simply understood as converting two-dimensional radar images into three-dimensional terrain maps.

[0049] First, the satellite-borne SAR transmits microwave signals towards the ground. The microwaves reach the target strip and are reflected back, where they are received by the satellite to form a SAR image. To obtain elevation information, at least two such images are needed. These images can be obtained by repeatedly observing the same area at different times by the same satellite, or by observing the same ground area simultaneously from different angles using a two-satellite or multi-satellite formation.

[0050] Next, interferometry is performed. Interferometry involves differentiating the phase information of the two SAR images to obtain an "interferogram." The phase difference reflects the distance difference between the target and the satellite from the perspectives of the two radars, and this distance difference includes terrain undulation information. Since the phase of the radar signal is 2π periodic, the observed phase difference often exhibits a folding phenomenon. Therefore, phase unwrapping must be performed, and algorithms are used to unfold the periodic phase to restore a continuous and true phase difference.

[0051] Next, by combining satellite orbit data, baseline lengths between satellites, and observation angles, the unwrapped phase difference is converted into actual ground elevation values. Through this process, relative phase information can be accurately calibrated into absolute elevation data. Finally, this elevation data is organized according to a specific spatial grid to generate a digital elevation model (DEM).

[0052] Figure 7 This is the working mode of mapping using a single-frequency, dual-satellite distributed InSAR satellite system. The single-frequency dual-satellite system utilizes two SAR antennas deployed along the vertical heading to simultaneously observe the same area from different perspectives, acquiring two composite SAR images. These two images are then interferometrically processed to calculate the slant range difference between the phase centers of the primary and secondary radar antennas and the ground target. Based on this, a digital elevation model of the observation area is retrieved.

[0053] With the continuous development of spaceborne InSAR technology, this single-frequency dual-satellite distributed InSAR satellite system can no longer meet the current requirements for mapping accuracy. In other words, a single-frequency dual-satellite distributed InSAR satellite system can only obtain one set of DEM sample data per flight, and a single set of DEM sample data is insufficient to meet the current mapping accuracy requirements.

[0054] To improve the accuracy of DEM mapping, a multi-frequency, multi-base distributed InSAR satellite system can be introduced. Specifically, by having at least three SAR formations of different frequencies fly together to transmit and receive radar waves at corresponding frequencies for the same target strip, multiple sets of interferometric pairs are obtained, forming multiple sets of DEM sample data, thereby improving the mapping accuracy.

[0055] In view of this, this application provides an engineering design method for a multi-frequency, multi-base InSAR satellite system, enabling a single SAR flight in formation to acquire multiple sets of DEM sample data. For ease of understanding, the number of SARs in this application is three. It should be emphasized that this application does not limit the number of SARs. The embodiment shown below uses a distributed InSAR satellite system and SARs as the execution subject to illustrate the method, but this application does not limit the execution subject. Any program that can run the code of the method provided in the embodiments of this application can implement the method provided in the embodiments of this application.

[0056] Figure 1 This is a schematic flowchart of an engineering design method for a multi-frequency, multi-base InSAR satellite system provided in this application.

[0057] Figure 2 This is a schematic diagram illustrating the working process of a multi-frequency, multi-base InSAR satellite system engineering design method provided in this application.

[0058] The following is a detailed explanation of the mapping working modes acquired by the multi-frequency, multi-base InSAR satellite system: This operating mode relies on three SARs operating at different frequencies, and these SARs are carried on a satellite. The specific steps include: The radar transmits radar waves toward the target strip via SAR; it receives radar wave signals at multiple operating frequencies via SAR to acquire multiple SAR images; and it generates multiple sets of DEM sample data based on the acquired SAR images.

[0059] Accordingly, SAR, as an important component of this distributed InSAR satellite system, specifically includes the following steps in acquiring SAR images: The system transmits radar waves toward the target strip; receives radar wave signals from multiple operating frequencies reflected by the target strip, and generates corresponding SAR images. The radar wave signals from multiple operating frequencies are transmitted by a corresponding number of SARs, of which there are three SARs, each with a different operating frequency; and sends SAR images to the InSAR satellite system.

[0060] For ease of explanation, the three SAR-equipped satellites are designated as Satellite A, Satellite B, and Satellite C, with operating frequencies of f1, f2, and f3, respectively. Figure 3 A logical diagram of this working mode in this embodiment is shown.

[0061] The above technical solution should be understood as follows: When satellites A, B, and C pass over the target strip, when the radar wave emitted by satellite A at operating frequency f1 reaches the target strip, after reflection, satellites A, B, and C simultaneously receive the radar wave signal, generating three SAR images and forming two sets of DEM sample data (AB) and (AC); when the radar wave emitted by satellite B at operating frequency f2 reaches the target strip, after reflection, satellites A, B, and C simultaneously receive the radar wave signal, generating three SAR images and forming two sets of DEM sample data (BA) and (BC); when the radar wave emitted by satellite C at operating frequency f3 reaches the target strip, after reflection, satellites A, B, and C simultaneously receive the radar wave signal, generating three SAR images and forming two sets of DEM sample data (CA) and (CB). Thus, a single pass can obtain 6 sets of DEM sample data, which is 2.4 times more accurate than a single-frequency dual-satellite InSAR satellite system that can only obtain one set per pass.

[0062] In this application, in addition to obtaining the mapping working mode, the following preparations are also required before the InSAR satellite system or SAR performs its mission (i.e., performs on-orbit work): The satellite formation configuration has been confirmed; the formation configuration of the three SARs of this InSAR satellite system is as follows: Figure 4As shown, specifically, in the engineering practice of distributed InSAR satellite systems, different inter-satellite positional relationships, i.e., different inter-satellite baseline lengths, are required for the characteristics of different mapping areas. For example, short baselines are needed for mountainous areas, areas with high vegetation, and deserts, while long baselines are needed for plains, hills, and bare soil and rock areas. Acquiring high-precision InSAR mapping data requires at least two satellites working together. However, a single flight of a two-satellite system can only guarantee a mapping baseline of one length. Using a multi-satellite system, multiple baselines of varying lengths can be acquired simultaneously during a single flight, thereby improving the system's mapping efficiency. There are many types of formation configurations for multi-base distributed InSAR satellite systems. This paper focuses on the engineering design method for multi-satellite, multi-band systems, a method generally applicable to various formation configurations of multi-satellite systems.

[0063] Understandably, this figure only shows one feasible approach. This application does not restrict the satellite formation configuration, as long as it meets the spatial baseline requirements for mapping by a multi-static InSAR satellite system. A baseline that is too short will result in insufficient altimeter sensitivity, while a baseline that is too long will easily lead to decoherence and affect the interferometric effect. The baseline direction needs to take into account the distribution in the heading and vertical directions to enrich the observation geometry. The satellite formation must maintain its relative position without instability over a long period of time; otherwise, baseline drift will make it difficult to align the observation data.

[0064] To determine the operating signal bandwidth between any two SARs, the bandwidth selection must be based on the requirements of the distributed InSAR satellite system, specifically, it must meet requirements such as image resolution and stripe width. Therefore, the operating signal bandwidth between any two SARs should satisfy the following formula:

[0065] Where B is the signal bandwidth. Where c is the image resolution and c is the speed of light. The incident angle for the SAR is [value].

[0066] Based on the operating signal bandwidth, the operating frequency of each SAR is determined. The operating frequency of each SAR needs to meet the application requirements of the distributed InSAR satellite system user. Specifically, it is necessary to ensure that f1, f2, and f3 do not interfere with each other, that is, to satisfy the following formula:

[0067]

[0068] Where f1, f2, and f3 are the operating frequencies of satellites A, B, and C, respectively, and B is the signal bandwidth.

[0069] It is important to note that the choice of operating frequency is primarily limited by the image resolution of the satellite system and relevant national regulations on radio frequencies. We will use the Samsung InSAR system with X-band, 2-meter resolution, and 3 frequencies as an example. The signal bandwidth required for 2-meter resolution is generally 160MHz. According to the "Regulations on Radio Frequency Allocation of the People's Republic of China," the usable frequency band for X-band SAR satellites is 9.3GHz~9.9GHz. Therefore, one option for the 3 frequencies could be 9.4GHz, 9.6GHz, or 9.8GHz, corresponding to frequency bands of 9.32GHz~9.48GHz, 9.52GHz~9.68GHz, and 9.72GHz~9.88GHz.

[0070] The operating timing of each SAR transmission is confirmed. Each SAR transmits radar waves simultaneously and receives radar wave signals reflected from the target stripe by all SARs. Specifically, the timing of receiving radar wave signals at different operating frequencies by individual SARs is simultaneous, such as... Figure 5 As shown, taking the Samsung InSAR system as an example, the three satellites are named A, B, and C, with their respective operating frequencies being f1, f2, and f3. All three satellites use the same operating bandwidth B and pulse repetition frequency (PRF). During operation, the three satellites simultaneously transmit electromagnetic waves to the ground according to their respective frequencies, signal bandwidths, and PRFs. Satellite A simultaneously receives echo signals from frequencies f1, f2, and f3, as do satellite B and satellite C.

[0071] Confirm the operating position of each SAR, such as Figure 6 As shown, traditional spaceborne SAR beamline design needs to consider factors such as image resolution, observation band width, orbital parameters, antenna aperture, operating mode, operating parameters, and beam pointing. Optimization design is carried out based on the analysis results of indicators such as system sensitivity and ambiguity. For multi-frequency, multi-base InSAR satellite systems, it is also necessary to consider that the pulse repetition frequency, number of sampling points, and signal bandwidth of multiple satellites must be kept consistent in the operating parameter design, and the sampling start time of multiple satellites must be jointly designed according to spatial geometric relationships.

[0072] It is understood that, in order to achieve the functions of the above embodiments, the distributed InSAR satellite system and SAR include hardware structures and / or software modules that perform the various functions. Those skilled in the art should readily recognize that, based on the units and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is performed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0073] The present invention also provides a SAR layout optimization system for distributed InSAR acquisition of regional DEM. The SAR layout optimization system for distributed InSAR acquisition of regional DEM can be implemented by executing the process steps of the method for the SAR layout optimization system for distributed InSAR acquisition of regional DEM. That is, those skilled in the art can understand the method for the SAR layout optimization system for distributed InSAR acquisition of regional DEM as a preferred embodiment of the SAR layout optimization system for distributed InSAR acquisition of regional DEM.

[0074] 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.

[0075] 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 of engineering design of a multi-frequency multi-static InSAR satellite system, characterized in that, The method comprises the following steps: Work mode acquisition: acquiring a multi-frequency multi-baseline InSAR satellite mapping work mode; Formation acquisition: acquiring a formation of a plurality of satellites, wherein the formation meets the spatial baseline requirements of the multi-baseline InSAR satellite system mapping; Work signal bandwidth acquisition: acquiring a work signal bandwidth between any two SARs, wherein the work signal bandwidth meets the image resolution, strip observation bandwidth, and ground positioning accuracy requirements; Work frequency point acquisition: acquiring a work frequency point of each SAR, wherein the work frequency points of each SAR are different; Work timing acquisition: acquiring a work timing of each SAR frequency division transmission; Work wave position acquisition: acquiring a work wave position of each SAR; In-orbit work execution: after confirming the acquisition of the work mode, the formation, the work signal, the work frequency point, the work timing, and the work wave position, performing multi-frequency multi-baseline wave position in-orbit work.

2. The method of claim 1, wherein, The work mode in the work mode acquisition step comprises: SARs with at least three different work frequency points sequentially emit radar waves to the same target strip; each SAR receives the radar wave signals reflected by the same target strip emitted by each SAR; a plurality of images generated by the SARs are acquired; and a plurality of groups of DEM sample data are formed according to the acquired images.

3. The method of claim 1, wherein, The work signal bandwidth between any two SARs meets the following formula: where B is the signal bandwidth, is the image resolution, c is the speed of light, is the SAR incidence angle.

4. The method of claim 4, wherein, The work frequency point of each SAR meets the following formula: wherein , , are working frequencies of different SARs, and n is a natural number greater than 2.

5. The method of claim 1, wherein, The work timing is that each SAR simultaneously transmits radar waves and receives radar wave signals reflected by the target strip emitted by all SARs, wherein the timing of a single SAR receiving radar wave signals with different work frequency points is simultaneous.

6. The method of claim 1, wherein, The work wave position acquisition step comprises: Acquiring system parameters, wherein the system parameters include image resolution, observation bandwidth, orbit parameters, antenna aperture, work mode, work parameters, and beam pointing; Analyzing the system parameters based on performance indicators, wherein the performance indicators include system sensitivity and ambiguity; Optimizing the wave position planning according to the analysis results; Controlling the pulse repetition frequency, the number of sampling points, and the signal bandwidth of each SAR to be consistent; Acquiring and analyzing the spatial geometric relationship between the SARs, and acquiring the sampling start time of the plurality of SARs.

7. A multi-frequency multi-static InSAR satellite system engineering design system, characterized in that, Comprise: Module M1: used for acquiring a multi-frequency multi-baseline InSAR satellite mapping work mode; Module M2: used for acquiring a formation of a plurality of satellites, wherein the formation meets the spatial baseline requirements of the multi-baseline InSAR satellite system mapping; Module M3: used for acquiring a work signal bandwidth between any two SARs, wherein the work signal bandwidth meets the image resolution, strip observation bandwidth, and ground positioning accuracy requirements; Module M4: used for acquiring a work frequency point of each SAR, wherein the work frequency points of each SAR are different; Module M5: used for acquiring a work timing of each SAR frequency division transmission; Module M6: used for acquiring a work wave position of each SAR; Module M7: used for performing multi-frequency multi-baseline wave position in-orbit work after confirming the acquisition of the work mode, the formation, the work signal, the work frequency point, the work timing, and the work wave position.

8. The system of claim 7, wherein, The work mode comprises: SARs of at least three different working frequencies are used to transmit radar waves to the same target strip in sequence; each SAR receives the radar wave signals reflected by the same target strip and transmitted by each SAR; a plurality of SAR-generated images are obtained; and a plurality of groups of DEM sample data are formed according to the obtained images.

9. The system of claim 7, wherein, The working signal bandwidths of any two SARs satisfy the following formula: where B is a signal bandwidth, is an image resolution, c is a speed of light, is a SAR incidence angle.

10. The system of claim 7, wherein, The working frequencies of each SAR satisfy the following formula: wherein , , are working frequencies of different SARs, and n is a natural number greater than 2.

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