A design method and device for high-resolution wide-band imaging mode of multi-base spaceborne SAR

Abstract

The present invention discloses a method and device for designing a high-resolution wide-band imaging mode for a multi-base satellite-borne SAR, and belongs to the technical field of high-resolution wide-band imaging for satellite-borne SAR. The method comprises constructing a primary-secondary satellite companion constellation for realizing simultaneous collaborative imaging of a wide-band ground area using multiple satellites; calculating the Doppler bandwidth of the primary-secondary satellite companion constellation according to satellite-ground geometric parameters, and designing wave position information; processing the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to realize wide transmission and narrow reception; evaluating the two-dimensional fuzziness and sensitivity of the imaging mode, terminating the iteration after meeting the imaging width requirement, and completing the optimization of the imaging parameters; transmitting a signal in orbit by the primary satellite, and transmitting the echoes by the primary satellite and all the auxiliary satellites to obtain a high-resolution wide-band image. The present invention can effectively multiply the quality factor of the system and realize high-resolution wide-band ground imaging.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-resolution and wide-width imaging modes of spaceborne synthetic aperture radars, and in particular relates to a method and device for designing a high-resolution and wide-width imaging mode of a multi-base spaceborne SAR. Background Art

[0002] High-resolution, wide-swath imaging (high-resolution, wide-swath) is the unwavering pursuit of Synthetic Aperture Radar (SAR). Multistatic spaceborne SAR technology, as the foundation for next-generation constellation networking, can also provide a path to achieving high-resolution, wide-swath imaging beyond traditional methods. Traditional multistatic SAR focuses more on issues such as phase synchronization and timing interferometry, with less discussion on how to achieve high-resolution, wide-swath imaging through collaborative work.

[0003] Therefore, studying the design method of high-resolution and wide-swath imaging mode based on multi-base spaceborne SAR will not only help enhance the research on related technologies for improving the system quality factor of multi-base spaceborne SAR, but also give multi-base SAR more application scenarios in the future. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method and device for designing a high-resolution wide-band imaging mode for a multi-base satellite-borne SAR, constructing a "primary satellite-auxiliary satellite" companion constellation, in which multiple satellites simultaneously perform collaborative imaging of a wide area on the ground; designing an orbital configuration, taking a three-star system as an example to design a nested multi-helix configuration; the primary satellite can transmit and receive signals, and the auxiliary satellite only needs to have a receiving function at least; designing a working mode, specifically, the primary satellite uses a wide beam to illuminate the ground, and the primary and auxiliary satellites use narrow beams to receive. According to the satellite-ground geometric parameters, the Doppler bandwidth is calculated, and the time width, bandwidth, pulse width, sampling rate and other wave position information are designed. In order to achieve a wide-transmit and narrow-receive design, it is necessary to process the antenna transmission pattern of the primary satellite, the antenna reception pattern of the primary satellite and the antenna reception pattern of the auxiliary satellite separately. Evaluate the two-dimensional ambiguity and sensitivity of the imaging mode, and complete the system design after iteration.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for designing a high-resolution wide-band imaging mode based on a multi-base spaceborne SAR, comprising:

[0007] Step S1: constructing a primary satellite-auxiliary satellite companion constellation to achieve collaborative imaging of a wide ground area using multiple satellites simultaneously;

[0008] Step S2: Calculate the Doppler bandwidth of the primary-secondary satellite constellation based on satellite-ground geometric parameters, and design beam position information based on the Doppler bandwidth, where the beam position information includes multiple groups of beam positions, and each group of beam positions includes multiple sub-bands;

[0009] Step S3: Process the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to achieve wide transmission and narrow reception;

[0010] Step S4: Iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirement is met, the iteration ends and the imaging parameter optimization is completed. The optimized imaging parameters are injected into the processors of the primary and auxiliary satellites. The primary satellite transmits the signal, and the primary satellite and all auxiliary satellites receive the echo and transmit it down. The images are uniformly stitched on the ground to obtain a high-resolution wide-width image.

[0011] In another aspect, the present invention provides a device for designing a high-resolution wide-band imaging mode based on a multi-base spaceborne SAR, comprising:

[0012] The constellation construction module is used to build a primary-secondary satellite companion constellation, which is used to achieve collaborative imaging of a wide area on the ground using multiple satellites at the same time;

[0013] A beam position design module is used to calculate the Doppler bandwidth of the primary satellite and auxiliary satellite companion constellation according to satellite-ground geometric parameters, and design beam position information based on the Doppler bandwidth, wherein the beam position information includes multiple groups of beam positions, each group of beam positions includes multiple sub-bands;

[0014] The pattern design module is used to process the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to achieve wide transmission and narrow reception;

[0015] The imaging module is used to iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirements are met, the iteration ends and the imaging parameters are optimized. The optimized imaging parameters are injected into the processors of the primary and auxiliary satellites. The primary satellite transmits the signal, and the primary satellite and all auxiliary satellites receive the echo and transmit it down. The images are uniformly stitched on the ground to obtain a high-resolution wide-width image.

[0016] In a third aspect, the present invention provides an electronic device comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned high-resolution wide-band imaging mode design method based on multi-base spaceborne SAR.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned high-resolution wide-band imaging mode design method based on multi-base spaceborne SAR.

[0018] The beneficial effects of the present invention are:

[0019] The present invention can effectively multiply the quality factor of the system and realize high-resolution and wide-width earth imaging; based on a multi-base spaceborne SAR platform, the goal can be achieved through reasonable orbit design, system wave position parameter design and transceiver antenna beam control, and the additional cost of engineering implementation is relatively low; the imaging quality and two-dimensional blur can meet the evaluation indicators of SAR images. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the working principle of the nested multi-helix configuration and imaging mode;

[0021] Figure 2 This is a flow chart of the method for designing a high-resolution wide-band imaging mode based on multi-base spaceborne SAR of the present invention;

[0022] Figure 3 This is a schematic diagram of a sample design of a multi-base high-resolution wide-band mode wave pattern;

[0023] Figure 4a is the NESZ simulation result based on the method of the present invention;

[0024] Figure 4b is the azimuth ambiguity simulation result based on the method of the present invention;

[0025] Figure 4c is the distance fuzzy simulation result based on the method of the present invention;

[0026] Figure 4d This is the simulation result of the distance-to-ground resolution based on the method of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings and examples.

[0028] The present invention provides a method for designing a high-resolution, wide-swath imaging mode for a multi-base spaceborne SAR (SAR). The method comprises one primary satellite and N auxiliary satellites flying in a nested multi-spiral formation. The primary satellite transmits using a wide beam to illuminate a wide scene. During reception, the primary and auxiliary satellites respectively image a single sub-band. By splicing, the image width is expanded N times without reducing the resolution. The high-resolution, wide-swath imaging mode based on the multi-base SAR described in the present invention provides a new approach for the engineering practice of high-quality factor imaging for spaceborne SAR.

[0029] In order to make the purpose and technical solutions of the present disclosure more clear, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0030] like Figure 2 As shown, the present invention provides a high-resolution wide-band imaging mode design method based on multi-base spaceborne SAR, comprising:

[0031] Step S1: Construct a primary-secondary satellite constellation, using multiple satellites to simultaneously capture a wide area of ​​the ground in collaborative stitching. This includes:

[0032] Step S1-1: Design the orbital configuration, taking the triple star system as an example to design a nested multi-helix configuration.

[0033] Step S1-2: Construct a primary satellite and secondary satellite companion constellation. The constellation is a one-primary-multiple-secondary design. The primary satellite can transmit and receive signals, and the secondary satellites only need to have a minimum receiving function.

[0034] The antenna of the main satellite is made of general TR components, while the antenna of the auxiliary satellite can use R components, which not only reduces the design complexity but also saves costs.

[0035] Step S1-3: Design the working mode, specifically, the main satellite uses a wide beam to illuminate the ground, and the main satellite and auxiliary satellite use narrow beams to receive.

[0036] Taking the "one main and two auxiliary" three-star system as an example, the working principle of the nested multi-helix configuration and imaging mode is as follows: Figure 1 As shown, two auxiliary satellites are arranged in a nested multi-spiral pattern around the primary satellite. Simultaneously, the three satellites orbit the Earth. Within each pulse repetition interval (PRI), the primary satellite first uses a broadened beam to illuminate the ground with a width of approximately 60 km. The three satellites then receive ground signal echoes from three sub-bands, each covering an area of ​​approximately 20 km. There is some overlap between the sub-bands, facilitating later mosaicking. Finally, a 60-km-wide strip-mode SAR image is obtained by stitching together the sub-bands.

[0037] Step S2: Calculate the Doppler bandwidth of the primary satellite-auxiliary satellite companion constellation based on the satellite-ground geometric parameters, and design the beam position information based on the Doppler bandwidth. The beam position information includes multiple groups of beam positions, and each group of beam positions includes several sub-bands.

[0038] Step S2-1: Calculate the satellite ground velocity and satellite velocity based on the satellite-ground geometric parameters, and calculate the Doppler bandwidth corresponding to the resolution set in the strip mode.

[0039] The satellite's ground-fixed velocity at each wave position is calculated by numerical simulation of the satellite's orbital elements (optional two-body model, J2 / J4, HPOP, etc.) and the speed of the wave foot on the ground , the Doppler bandwidth can be calculated , the formula is as follows:

[0040] ,

[0041] in, represents the 3dB beamwidth in azimuth, λ represents the wavelength, and for the case of no filtering, the native resolution of the strip It can be estimated by the following formula:

[0042] ,

[0043] in, represents the point target broadening coefficient, which is obtained by multiplying multiple factors. The above formula shows that for fixed beam width and velocity parameters, the native resolution that the system can obtain does not exceed , considering the system design margin, we can perform a certain amount of Doppler filtering on this basis and reduce the resolution to the required target strip resolution.

[0044] Step S2-2: Determine the lower limit of the pulse repetition frequency (PRF) according to the Doppler bandwidth, and select a suitable oversampling rate to ensure that the azimuth ambiguity is sufficiently low.

[0045] According to the sampling law, the sampling rate needs to exceed the bandwidth by a certain multiple, which is called the oversampling rate. However, the PRF should not be set too high. Generally, the PRF is selected so that the azimuth ambiguity and distance ambiguity are both less than -20dB.

[0046] Step S2-3: Select a suitable beam position within the ground visibility range. When selecting beam positions, it is necessary to ensure that the PRFs of adjacent beam positions are the same and that the coverage areas overlap to a certain extent.

[0047] The sample design of multi-base high-resolution wide-band mode wave pattern is as follows: Figure 3 As shown in the figure, in order to achieve an azimuth resolution of more than 2m, the simulation results of a typical low-orbit orbit show that the Doppler bandwidth is about 2500~3000. Therefore, the PRF is selected in the range of about 4600~4800, which meets the requirement of azimuth ambiguity less than -20dB. Since the echoes of the four sub-bands are all emitted by the main satellite using the same pulse frequency, the four satellites also choose to maintain the same PRF when receiving echoes from different perspectives. Figure 3 It can be seen that the three sub-bands in each group of wavelets share the same PRF, while the wavelets in different groups are flexibly selected.

[0048] Compared with the general spaceborne SAR wave pattern, it is noted that some wave patterns overlap with the transmission window (the dark band in the wave pattern). For general spaceborne SAR systems, this design causes the transmission window to block signal reception. However, when designing this system, the wave pattern of the primary satellite responsible for transmitting the signal is chosen to avoid the transmission window, while the auxiliary satellite can receive signals when the primary satellite transmits. Therefore, the wave patterns in the wave pattern that overlap with the transmission window are all the wave patterns of the auxiliary satellite.

[0049] Step S2-4: further calculating the signal time width, bandwidth, pulse width and sampling rate parameters according to the PRF and duty cycle.

[0050] To achieve ground resolution , the required bandwidth Not less than:

[0051] ,

[0052] in, represents the point target broadening coefficient, c represents the speed of light, Represents the incident angle of the radar wave to the ground;

[0053] Pulse Width It is generally a function of the duty cycle:

[0054] ,

[0055] Here, PWM stands for duty cycle, and its typical value is 10%.

[0056] The sampling rate is generally set to be greater than 1.2 times the signal bandwidth and is an integer multiple of the AD high-speed clock.

[0057] Step S3: In order to achieve the wide transmit and narrow receive design, the antenna transmit pattern of the primary satellite, the antenna receive pattern of the primary satellite, and the antenna receive pattern of the auxiliary satellite need to be processed separately. This includes:

[0058] Step S3-1: widen the primary satellite's antenna transmission pattern to cover a wide imaging area.

[0059] During transmission, pure phase-weighted excitation is used to broaden the radiation pattern in order to minimize the power loss and additional gain loss due to broadening.

[0060] Step S3-2: Design the sidelobe suppression for the antenna receiving patterns of the primary and secondary satellites, and reduce the level of the first sidelobe as much as possible without significantly widening the mainlobe.

[0061] During reception, the first sidelobe can be suppressed by using an amplitude weighting method, thereby suppressing the range ambiguity energy caused by wide-band transmission with a lower signal-to-noise ratio loss.

[0062] Step S4: Iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirement is met, the iteration ends and the imaging parameter optimization is completed. The optimized imaging parameters are injected into the processors of the primary and secondary satellites. The primary satellite transmits the signal, and the primary satellite and all secondary satellites receive the echo and transmit it down. The images are stitched together on the ground to obtain a high-resolution wide-width image. This includes:

[0063] Step S4-1: Calculate the system sensitivity of the high-resolution wide-band imaging mode:

[0064] ,

[0065] in, is the slant distance, is the total system loss including the effects of thermal noise, is the system noise figure, K is the Boltzmann constant, T is the temperature (in Kelvin), B r is the system bandwidth, is the azimuth integrated loss, Indicates the bottom viewing angle, is the Earth-fixed velocity of the satellite at each wave position, For the lower perspective The corresponding angle of incidence, is the transmit power, is the pulse repetition frequency, is the pulse width, is the power pattern of the transmitting antenna and the receiving antenna in elevation, is the carrier wavelength, It is the speed of light. It is worth noting that when calculating the sensitivity of the primary satellite, both the transmission and reception are based on the primary satellite, while when calculating the sensitivity of the auxiliary satellite, the transmission pattern is based on the primary satellite, while the receiving antenna pattern is based on the auxiliary satellite.

[0066] Step S4-2: Calculate the azimuth ambiguity of the high-resolution wide-band imaging mode:

[0067] ,

[0068] in, is the azimuth transmitting antenna pattern, is the azimuth receiving antenna pattern, B dop is the width of the filtered Doppler bandwidth corresponding to the stripe pattern azimuth resolution. m represents the azimuth ambiguity number. When m is 0, it represents the main signal energy; when m is not 0, it represents the ambiguity energy of each order. f is the Doppler frequency. It is worth noting that when calculating azimuth ambiguity for the primary satellite, both transmission and reception use the primary satellite's data. When calculating azimuth ambiguity for the secondary satellite, the transmit antenna pattern uses the primary satellite's data, while the receive antenna pattern uses the secondary satellite's data.

[0069] Step S4-3: Calculate the range ambiguity of the high-resolution wide-band imaging mode:

[0070]

[0071] in, Representing perspective, Represents the ground scattering coefficient, which varies with the incident angle and the fuzzy number n changes. When n is 0, it is the main signal energy, and when n is not 0, it is the fuzzy (amb) energy. R represents the slant range. is the elevation transmitting antenna pattern, It is the receiving antenna pattern in elevation. It is worth noting that when the primary satellite is calculated for range ambiguity, both transmission and reception use the primary satellite, while when the auxiliary satellite is calculated for range ambiguity, the transmission pattern uses the primary satellite, while the receiving antenna pattern uses the auxiliary satellite.

[0072] Step S4-4: Perform an index assessment on the system sensitivity, azimuth ambiguity, and range ambiguity. If the requirements are not met, redesign the beam position or optimize the antenna pattern, and iterate the design. If the indicators meet the requirements, the design is completed.

[0073] Step S4-5: Injecting the optimized imaging parameters into the processors of the primary and secondary satellites;

[0074] Step S4-6: The operation is carried out according to the pre-planned imaging area, with the primary satellite transmitting the signal and the primary satellite and all the auxiliary satellites receiving the echo;

[0075] Step S4-7: The data is transmitted downlink and uniformly stitched on the ground to obtain a large high-resolution and wide-width image.

[0076] Based on experience, X-band spaceborne SAR design requires azimuth ambiguity better than -20 dB. This is sufficient for most areas of the NESZ and RASR. Since beam position selection inevitably overlaps with the sub-satellite point, the range ambiguity suppression capability is limited, allowing the edge to slightly exceed the -20 dB constraint. If the simulation results deviate significantly from the target, iterative design is required. After iteration, a set of beam position designs with minimal range ambiguity tolerance can be obtained. This process is mentioned in many existing technologies for spaceborne SAR system design and will not be repeated here.

[0077] The present invention describes the method for implementing the working mode, the evaluation and iterative process, and provides a new implementation approach for the engineering practice of high quality factor imaging of spaceborne SAR through the method described in the present disclosure.

[0078] In the embodiments of the present disclosure, refer to Figure 1 The following figure shows the principle diagram of the high-resolution wide-swath imaging mode of a multi-base spaceborne SAR in a nested multi-helix configuration. Within the visible area, the primary satellite uses a wide beamwidth to illuminate a swath of approximately 60 km at a time. The three satellites then use narrow beamwidths to receive echoes from three sub-bands of the wide-swath scene. This imaging mode does not impose excessive constraints in azimuth, so the swath width does not need to be increased at the expense of resolution, improving the system's quality factor. In addition, due to the narrow beamwidth used during reception, this mode still has a strong ability to suppress range ambiguity. Imaging simulation results generally exceed -20dB, and the imaging effect can meet the requirements of the application.

[0079] In the embodiments of the present disclosure, refer to Figure 3The figure shows a typical beam position design example of a multi-base spaceborne SAR. The dark strips in the figure represent transmission window obstructions, the light strips represent sub-satellite point echoes, and the vertical bars represent beam positions. Three beam positions form a group, and each beam position covers an area of ​​about 20 kilometers. After splicing and combination, a width of 60 kilometers is obtained. In each group of beam positions, at least one beam position is not restricted by transmission window obstruction, which is the receiving window beam position of the primary satellite. The other two beam positions that may be obstructed by the transmission window are the auxiliary satellite beam positions. Since the auxiliary satellite itself does not transmit signals, the obstruction does not actually affect the normal operation of the system.

[0080] In the embodiments of the present disclosure, refer to Figure 4a-4d The system performance simulation results shown in Figure 4a This is the NESZ simulation result. As can be seen from the figure, most areas are below -20dB. However, due to the limited power and aperture size of the small satellite, the power-aperture product is insufficient, so the signal-to-noise ratio at some image edges is still slightly low, which is acceptable from the perspective of the final image quality. Figure 4b The following figure shows the simulation results of azimuth ambiguity. As shown in the figure, for the wave position design with a PRF in the range of 4600~4800, the azimuth ambiguity can be better than -20dB. Figure 4c The figure shows the simulation results of range ambiguity. For this example wave position design, the range ambiguity in most areas is better than -20dB. There are some areas that inevitably exceed the tolerance, but this does not affect the overall design. Figure 4d The simulation results of the range-to-ground resolution show that the bandwidth of the transmitted signal at each wave position is reasonably designed, and the range-to-ground resolution can be better than 2m within the visible incident angle range.

[0081] The embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. It should be noted that any implementations not depicted or described in the drawings or the main text of the specification are known to those skilled in the art and are not described in detail. Furthermore, the above definitions of the various elements and methods are not limited to the various specific structures, shapes, or methods described in the embodiments, and can be easily modified or replaced by those skilled in the art.

[0082] Based on the above description, those skilled in the art should have a clear understanding of a method for designing a high-resolution wide-swath imaging mode based on multi-base spaceborne SAR.

[0083] On the other hand, the present invention provides a device for designing a high-resolution wide-band imaging mode based on a multi-base spaceborne SAR, wherein the modules included in the device can implement the various steps of the aforementioned method, specifically including:

[0084] The constellation construction module is used to build a primary-secondary satellite companion constellation, which is used to achieve collaborative imaging of a wide area on the ground using multiple satellites at the same time;

[0085] A beam position design module is used to calculate the Doppler bandwidth of the primary satellite and auxiliary satellite companion constellation according to satellite-ground geometric parameters, and design beam position information based on the Doppler bandwidth, wherein the beam position information includes multiple groups of beam positions, each group of beam positions includes multiple sub-bands;

[0086] The pattern design module is used to process the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to achieve wide transmission and narrow reception;

[0087] The imaging module is used to iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirements are met, the iteration ends and the imaging parameters are optimized. The optimized imaging parameters are injected into the processors of the primary and auxiliary satellites. The primary satellite transmits the signal, and the primary satellite and all auxiliary satellites receive the echo and transmit it down. The images are uniformly stitched on the ground to obtain a high-resolution wide-width image.

[0088] In a third aspect, the present invention provides an electronic device comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned high-resolution wide-band imaging mode design method based on multi-base spaceborne SAR.

[0089] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned high-resolution wide-band imaging mode design method based on multi-base satellite-borne SAR.

[0090] In summary, this disclosure provides a method for designing high-resolution, wide-band imaging modes for multi-base spaceborne SAR. In this embodiment, the method for implementing this operating mode, along with the evaluation and iteration processes, is described. A design example is presented with accompanying figures. Quantitative simulations and analysis of various spaceborne SAR performance indicators verify the effectiveness of the proposed design method. This method provides a new approach for engineering practice in achieving high-quality factor-of-merit imaging for spaceborne SAR.

[0091] It should also be noted that directional terms such as "upper," "lower," "front," "back," "left," and "right" mentioned in the embodiments are merely references to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, identical elements are represented by identical or similar reference numerals. Conventional structures or configurations will be omitted where they may cause confusion in understanding this disclosure.

[0092] Furthermore, the shapes and sizes of the components in the figures do not reflect the actual sizes and proportions, but are merely illustrative of the contents of the embodiments of the present disclosure. In addition, in the claims, any reference signs placed between brackets should not be construed as limiting the claims.

[0093] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate and can vary depending on the desired properties obtained through the teachings of this disclosure. Specifically, all numbers used in the specification and claims to express compositional amounts, reaction conditions, and the like are to be understood as being modified in all instances by the term "about." Generally, such expressions are intended to encompass variations of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments, from the specified quantity.

[0094] Furthermore, the word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0095] The use of ordinal numbers such as "first," "second," and "third" in the specification and claims to modify corresponding elements does not in itself mean that the elements have any ordinal number, nor does it represent the order of one element relative to another or the order in the manufacturing method. The use of such ordinal numbers is only used to clearly distinguish one element with a certain name from another element with the same name.

[0096] Furthermore, unless specifically described or required to occur sequentially, the order of the steps is not limited to the order listed above and may be varied or rearranged based on desired design requirements. Furthermore, the above embodiments may be mixed and matched with each other or with other embodiments based on design and reliability considerations. That is, the technical features of different embodiments may be freely combined to form more embodiments.

[0097] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into a plurality of submodules or subunits or subcomponents. All features disclosed in this specification (including the accompanying claims, abstract and drawings) and all processes or units of any method or device so disclosed may be combined in any combination, except that at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose. Furthermore, in a unit claim enumerating a number of devices, several of these devices may be embodied by the same item of hardware.

[0098] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of the present disclosure, various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed approach should not be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as reflected in the claims below, the disclosed aspects consist of fewer than all the features of the individual embodiments disclosed above. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present disclosure.

[0099] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR, characterized in that: The method comprises: Step S1: constructing a primary satellite-auxiliary satellite companion constellation to achieve collaborative imaging of a wide ground area using multiple satellites simultaneously; Step S2: Calculate the Doppler bandwidth of the primary-secondary satellite constellation based on satellite-ground geometric parameters, and design beam position information based on the Doppler bandwidth, where the beam position information includes multiple groups of beam positions, and each group of beam positions includes multiple sub-bands; Step S3: Process the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to achieve wide transmission and narrow reception; Step S4: Iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirement is met, the iteration ends and the imaging parameter optimization is completed. The optimized imaging parameters are injected into the processors of the primary and auxiliary satellites. The primary satellite transmits the signal, and the primary satellite and all auxiliary satellites receive the echo and transmit it down. The images are uniformly stitched on the ground to obtain a high-resolution wide-width image.

2. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 1, wherein: The step S1 comprises: Step S1-1, designing the orbital configuration to be a nested multi-helix configuration in which the auxiliary star orbits the primary star; Step S1-2: constructing a primary satellite-auxiliary satellite companion constellation with one primary satellite and multiple auxiliary satellites, wherein the primary satellite is used to transmit and receive signals, and the auxiliary satellites are only used to receive signals; Step S1-3: Designing a working mode, wherein the primary satellite uses a wide beam to illuminate the ground, and the primary satellite and the auxiliary satellite use narrow beams to receive signals.

3. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 1, wherein: The step S2 comprises: Step S2-1: Calculate the satellite ground velocity and satellite velocity based on the satellite-ground geometric parameters, and calculate the Doppler bandwidth corresponding to the resolution set in the strip mode; Step S2-2, determining a lower limit of a pulse repetition frequency (PRF) according to the Doppler bandwidth; Step S2-3: Select beam positions within the ground visible range, where adjacent beam positions have the same PRF and their coverage areas overlap. Step S2-4: Calculate the signal time width, bandwidth, pulse width, and sampling rate parameters based on the PRF and duty cycle.

4. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 1, wherein: The step S3 comprises: Step S3-1: widen the primary satellite's antenna transmission pattern to cover a wide imaging area; Step S3-2: Design the sidelobe suppression for the antenna receiving patterns of the primary and secondary satellites.

5. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 1, wherein: The step S4 comprises: Step S4-1: Calculating the system sensitivity of the high-resolution wide-band imaging mode; Step S4-2: Calculating the azimuth ambiguity of the high-resolution wide-band imaging mode; Step S4-3: Calculating the range ambiguity of the high-resolution wide-band imaging mode; Step S4-4: Perform an index assessment on the system sensitivity, azimuth ambiguity, and range ambiguity. If the system meets the requirements for high-resolution wide-band imaging, the design is completed. Step S4-5: Injecting the optimized imaging parameters into the processors of the primary and secondary satellites; Step S4-6: The operation is carried out according to the pre-planned imaging area, with the primary satellite transmitting the signal and the primary satellite and all the auxiliary satellites receiving the echo; Step S4-7: The data is transmitted downlink and uniformly stitched on the ground to obtain a large high-resolution and wide-width image.

6. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 5, wherein: In the calculation process of the system sensitivity, azimuth ambiguity, and range ambiguity, the transmit and receive parameters involved in the calculation of the primary satellite use those of the primary satellite, while the transmit directional pattern involved in the calculation of the auxiliary satellite uses those of the primary satellite, and the receive antenna directional pattern uses those of the auxiliary satellite.

7. The method for designing a high-resolution wide-band imaging mode for a multi-base spaceborne SAR according to claim 5, wherein: In step S4-4, if the high-resolution wide-width imaging requirement is not met, steps S4-2 to S4-3 are re-executed.

8. A high-resolution wide-band imaging mode design device for multi-base spaceborne SAR, characterized in that: include: The constellation construction module is used to build a primary-secondary satellite companion constellation, which is used to achieve collaborative imaging of a wide area on the ground using multiple satellites at the same time; A beam position design module is used to calculate the Doppler bandwidth of the primary satellite and auxiliary satellite companion constellation according to satellite-ground geometric parameters, and design beam position information based on the Doppler bandwidth, wherein the beam position information includes multiple groups of beam positions, each group of beam positions includes multiple sub-bands; The pattern design module is used to process the primary satellite's antenna transmission pattern, the primary satellite's antenna reception pattern, and the auxiliary satellite's antenna reception pattern separately to achieve wide transmission and narrow reception; The imaging module is used to iteratively evaluate the two-dimensional blur and sensitivity of the imaging mode. When the imaging width requirements are met, the iteration ends and the imaging parameters are optimized. The optimized imaging parameters are injected into the processors of the primary and auxiliary satellites. The primary satellite transmits the signal, and the primary satellite and all auxiliary satellites receive the echo and transmit it down. The images are uniformly stitched on the ground to obtain a high-resolution wide-width image.

9. An electronic device, characterized in that: include: one or more processors; a memory for storing one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the high-resolution wide-band imaging mode design method for a multi-base spaceborne SAR as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that Executable instructions are stored thereon, and when the instructions are executed by a processor, the processor can implement a high-resolution wide-band imaging mode design method for a multi-base spaceborne SAR as described in any one of claims 1 to 7.

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