Imaging Quality Evaluation Method, Device, Equipment and Medium for Synthetic Aperture Radar

Abstract

The present application discloses a method, device, equipment and medium for evaluating the imaging quality of a synthetic aperture radar, relating to the technical field of radar imaging. The method includes: when it is monitored that a synthetic aperture radar satellite enters a preset monitoring range, determining a target synthetic aperture radar signal source and acquiring the corresponding transmitted signal; extracting target characteristic parameters from the transmitted signal and determining the working mode and imaging parameters of the target synthetic aperture radar signal source; using the target characteristic parameters to update the spectral fingerprint of the target synthetic aperture radar signal source in real time, and evaluating the imaging ability of the echo signal of the target synthetic aperture radar signal source based on the spectral fingerprint, target characteristic parameters, working mode and imaging parameters to generate an imaging ability evaluation result. Through the technical solution of the present application, a comprehensive evaluation of the working state of the signal source and the potential imaging performance can be realized in a non-cooperative scenario, overcoming the limitations of the prior art's dependence on active signal cooperation and echo imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of radar imaging, and particularly relates to an imaging quality evaluation method, device, equipment and medium for a synthetic aperture radar. Background Art

[0002] Synthetic Aperture Radar (SAR) is an important tool for modern remote sensing technology and space observation. By actively emitting electromagnetic waves and receiving echo signals, SAR can achieve all-weather and high-resolution ground imaging. SAR has important applications in space target monitoring and imaging, and the imaging performance of its echo signals directly determines the accuracy and efficiency of earth observation. Therefore, it is necessary to evaluate its imaging quality. Imaging quality evaluation has a direct impact on improving image quality and application effects. High-quality SAR images can more accurately reflect the surface conditions, thereby improving the reliability of information and the accuracy of decision-making, and thus enhancing the effectiveness of the entire SAR system.

[0003] Traditional SAR imaging quality evaluation methods mainly rely on the imaging results generated from SAR echo signals. These methods rely on the active cooperation of the SAR signal source, that is, it is necessary to capture the signals emitted by the SAR system. The echo signals are processed to generate images, and then the quality of the images is evaluated by calculating image quality metrics (such as contrast, edge sharpness, information entropy, etc.). However, this method highly depends on the active cooperation of the signal source, making it difficult to use in non-cooperative scenarios; and by analyzing the imaging results generated from the echo signals, it is impossible to evaluate the SAR performance in the case of missing echo signals or incomplete imaging.

[0004] Therefore, how to provide a solution to the above technical problems is an issue that those skilled in the art need to solve currently. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an imaging quality evaluation method, device, equipment and medium for a synthetic aperture radar, which can comprehensively evaluate the working state of the signal source and potential imaging performance in non-cooperative scenarios, and overcome the limitations of the prior art's dependence on active signal cooperation and echo imaging. The specific solutions are as follows:

[0006] In the first aspect, the present application discloses an imaging quality evaluation method for a synthetic aperture radar, including:

[0007] When it is monitored that the synthetic aperture radar satellite enters the preset monitoring range, determine the target synthetic aperture radar signal source and obtain the transmitted signal of the target synthetic aperture radar signal source;

[0008] Extract the target feature parameters from the transmitted signal, and determine the operating mode and imaging parameters of the target synthetic aperture radar signal source according to the target feature parameters;

[0009] Use the target feature parameters to update the spectral fingerprint of the target synthetic aperture radar signal source in real time, and evaluate the imaging ability of the echo signal of the target synthetic aperture radar signal source based on the spectral fingerprint, the target feature parameters, the operating mode and the imaging parameters to generate an imaging ability evaluation result; wherein, the spectral fingerprint is generated by associating the target feature parameters with the identification information of the target synthetic aperture radar signal source, and is a feature that can be continuously accumulated and updated based on historical data.

[0010] Optionally, when it is monitored that the synthetic aperture radar satellite enters the preset monitoring range, determining the target synthetic aperture radar signal source and obtaining the transmitted signal of the target synthetic aperture radar signal source includes:

[0011] Obtain the two-line orbital ephemeris data of the synthetic aperture radar satellite, and use the two-line orbital ephemeris data to determine the satellite trajectory of the synthetic aperture radar satellite;

[0012] Monitor the synthetic aperture radar satellite in real time through the antenna to determine whether the satellite trajectory is within the preset monitoring range;

[0013] When the satellite trajectory is within the preset monitoring range, determine that the synthetic aperture radar satellite enters the preset monitoring range;

[0014] When the electromagnetic signal transmitted by the synthetic aperture radar satellite is received by the electromagnetic signal receiving device within the preset monitoring range, determine the current synthetic aperture radar satellite as the target synthetic aperture radar signal source, and use the electromagnetic signal as the transmitted signal of the target synthetic aperture radar signal source.

[0015] Optionally, after obtaining the transmitted signal of the target synthetic aperture radar signal source, it further includes:

[0016] Perform analog processing on the transmitted signal to convert the transmitted signal into a baseband signal;

[0017] Perform analog-to-digital conversion on the baseband signal to generate a corresponding digital signal;

[0018] Correspondingly, extracting the target feature parameters from the transmitted signal includes:

[0019] Extract features from the baseband signal and the digital signal respectively to obtain the target feature parameters.

[0020] Optionally, extracting the target feature parameters from the transmitted signal includes:

[0021] Performing real-time spectrum analysis on the transmitted signal based on digital radio frequency technology to extract the target frequency domain features in the digital signal;

[0022] Performing time domain feature measurement on the transmitted signal based on pulse measurement technology to extract the target time domain features in the digital signal;

[0023] Analyzing the antenna pattern to determine the target transmission characteristics of the transmitted signal;

[0024] Determining the target feature parameters of the transmitted signal based on the target frequency domain features, the target time domain features, and the target transmission characteristics.

[0025] Optionally, determining the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target feature parameters includes:

[0026] Analyzing the target feature parameters respectively through a mode classification algorithm, a multi-baseline analysis algorithm, and a polarization recognition algorithm to determine the working mode and imaging parameters of the target synthetic aperture radar signal source.

[0027] Optionally, the imaging quality evaluation method of the synthetic aperture radar further includes:

[0028] Constructing an electromagnetic database of space targets, and respectively setting an electromagnetic feature table, a spectrum fingerprint table, a time series table, a working parameter table, and an imaging ability table in the electromagnetic database of space targets;

[0029] Among them, the electromagnetic feature table is used to record the target feature parameters, the spectrum fingerprint table is used to store the spectrum fingerprint, the time series table is used to record the time dimension change trajectory of the spectrum features of the transmitted signal, the working parameter table is used to store the working mode and imaging parameters of the target synthetic aperture radar signal source, and the imaging ability table is used to store the imaging ability evaluation result.

[0030] Optionally, using the target feature parameters to update the spectrum fingerprint of the target synthetic aperture radar signal source in real time includes:

[0031] Determining the identification information of the target synthetic aperture radar signal source according to the two-line orbital ephemeris data of the target synthetic aperture radar signal source;

[0032] Associating the target feature parameters with the identification information to generate the spectrum fingerprint of the target synthetic aperture radar signal source, and updating the spectrum fingerprint in real time based on the time dimension change trajectory in the time series table.

[0033] In a second aspect, the present application discloses an imaging quality evaluation device for a synthetic aperture radar, comprising:

[0034] a signal acquisition module, configured to determine a target synthetic aperture radar signal source and obtain a transmitted signal of the target synthetic aperture radar signal source when it is detected that a synthetic aperture radar satellite enters a preset monitoring range;

[0035] a signal analysis module, configured to extract target feature parameters from the transmitted signal and determine an operating mode and imaging parameters of the target synthetic aperture radar signal source according to the target feature parameters;

[0036] a performance evaluation module, configured to use the target feature parameters to update a spectrum fingerprint of the target synthetic aperture radar signal source in real time, and evaluate an imaging ability of an echo signal of the target synthetic aperture radar signal source based on the spectrum fingerprint, the target feature parameters, the operating mode, and the imaging parameters to generate an imaging ability evaluation result; wherein the spectrum fingerprint is a feature generated by associating the target feature parameters with identification information of the target synthetic aperture radar signal source and can be continuously accumulated and updated based on historical data.

[0037] In a third aspect, the present application discloses an electronic device, which includes a processor and a memory; wherein, the memory is used to store a computer program, and the computer program is loaded and executed by the processor to implement the imaging quality evaluation method for a synthetic aperture radar as described above.

[0038] In a fourth aspect, the present application discloses a computer-readable storage medium for storing a computer program; wherein the computer program, when executed by a processor, implements the imaging quality evaluation method for a synthetic aperture radar as described above.

[0039] The beneficial technical effects of the present application are as follows: First, when it is detected that the synthetic aperture radar satellite enters the monitoring range, the target synthetic aperture radar signal source is determined, realizing passive reception of the transmitted signal of the target synthetic aperture radar signal source in a non-cooperative scenario. Second, by analyzing the target characteristic parameters extracted from the transmitted signal, the operating mode and imaging parameters of the target synthetic aperture radar signal source are determined, making the utilized characteristic granularity finer, more complete, and more comprehensive. Finally, the spectral fingerprint is updated in real time using the extracted target characteristic parameters, and the imaging ability of the echo signal is evaluated by combining the target characteristic parameters, operating mode, and imaging parameters to generate the final imaging ability evaluation result, making the imaging quality evaluation of the synthetic aperture radar more and more comprehensive and accurate. It can be seen that the present invention gets rid of the dependence on active signal cooperation; by inferring the operating mode and imaging parameters of the signal source using the passively received transmitted signal, the imaging ability of the signal source can be estimated in the case of missing echo signals or unable to obtain imaging results; and it can cover the entire life cycle of data collection, analysis, and evaluation, flexibly adapt, and provide a wider applicability for the performance evaluation of the signal source.

[0040] In addition, an imaging quality evaluation device, equipment, and storage medium for a synthetic aperture radar provided by the present application correspond to the above imaging quality evaluation method for a synthetic aperture radar, and the effects are the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings according to the provided drawings without creative efforts.

[0042] Figure 1 It is a flowchart of an imaging quality evaluation method for a synthetic aperture radar disclosed in the present application;

[0043] Figure 2 It is a flowchart of a SAR imaging quality evaluation system disclosed in the present application;

[0044] Figure 3 It is an architecture diagram of a SAR imaging quality evaluation system disclosed in the present application;

[0045] Figure 4 It is a schematic structural diagram of an imaging quality evaluation device for a synthetic aperture radar disclosed in the present application;

[0046] Figure 5 It is a structural diagram of an electronic device disclosed in the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0048] Synthetic Aperture Radar (SAR) is an important tool for modern remote sensing technology and space observation. By actively emitting electromagnetic waves and receiving echo signals, SAR can achieve all-weather and high-resolution ground imaging. SAR radar observation satellites have some advantages that optical satellites do not have, including high resolution, being unaffected by day or night and weather, strong penetration, and can use radar signals of different wavelengths to focus on observing and imaging ground buildings, personnel, metals, land, etc., and are widely used in fields such as earth remote sensing, military monitoring, and disaster assessment.

[0049] In order to adapt to complex observation requirements, the SAR system needs to achieve a balance among imaging resolution, mapping swath, and resource efficiency. In recent years, with the development of SAR technology, multi-static SAR systems and multi-mode SAR systems (such as stripmap, spotlight, and fanbeam modes) have gradually become research hotspots. Their transmitted signals and operating parameters are more complex, posing higher requirements for the evaluation of their performance.

[0050] Synthetic Aperture Radar (SAR) has important applications in space target monitoring and imaging. The imaging performance of its echo signal directly determines the accuracy and efficiency of earth observation. Traditional SAR imaging quality assessment methods usually generate imaging results based on SAR echo signals. These methods rely on the active cooperation of the SAR signal source, that is, it is necessary to capture the signals transmitted by the SAR system. The echo signals are processed to generate images, and then by analyzing the images generated by the echo signals, the quality is evaluated by calculating the quality metrics of the images (such as contrast, edge sharpness, information entropy, etc.) to evaluate whether the imaging parameters meet the task requirements. However, in the prior art, the comprehensive methods for real-time monitoring of SAR satellite transmitted signals, signal feature extraction, spectrum analysis, and imaging performance evaluation are not yet perfect. There are problems especially in the following aspects:

[0051] 1. Lack of signal analysis in non-cooperative scenarios: Existing technologies often perform forward analysis of satellite performance and quality assessment of imaging through SAR echo signals, which requires the active participation and cooperation of the SAR signal source. For example, in mission planning or experimental scenarios, the SAR transmitted signal is pre-designed and analyzed in cooperation with the receiving end. This method lacks the ability to evaluate the working parameters of the signal source and the echo imaging performance using the SAR transmitted signal in non-cooperative scenarios (such as space target monitoring or unknown SAR signal analysis). That is, it is impossible to effectively evaluate the working state and imaging performance of the SAR signal source without the active cooperation of the signal source;

[0052] 2. Incomplete parameter extraction: In existing methods, the feature extraction of SAR signals is limited to only some key parameters, lacking the ability of passive signal analysis. It is impossible to directly infer the working mode and other states, key parameters (such as carrier frequency, bandwidth, modulation method, etc.) of the signal source and the potential imaging performance of the signal source by receiving the SAR transmitted signal in non-cooperative scenarios, and it is impossible to comprehensively analyze the SAR working mode and imaging ability. This results in a lack of flexibility and applicability of evaluation means in complex mission environments;

[0053] 3. Lack of real-time performance: The generation of SAR echo signals in existing technologies lags behind the transmitted signal, and only analyzing the echo signals cannot meet the demand for real-time evaluation of SAR imaging performance;

[0054] 4. Lack of systematicness: Existing systems cannot provide a complete closed-loop process from SAR signal tracking and acquisition to imaging performance evaluation;

[0055] 5. Insufficient adaptation to multi-static SAR systems: The analysis of the transmitted signal characteristics of multi-static SAR systems is not comprehensive enough, making it difficult to meet the evaluation requirements of complex SAR systems;

[0056] 6. Dependence on single imaging: Existing evaluation methods focus on quality analysis through images generated by echo signals, and do not fully utilize the information characteristics of the SAR transmitted signal itself, making it difficult to perform performance evaluation in the case of missing echo signals or incomplete image imaging.

[0057] Therefore, this application provides an imaging quality evaluation scheme for synthetic aperture radar, which can comprehensively evaluate the working state of the signal source and the potential imaging performance in non-cooperative scenarios, overcoming the limitations of existing technologies' dependence on active signal cooperation and echo imaging.

[0058] The embodiment of the present invention discloses an imaging quality evaluation method for synthetic aperture radar. As shown in Figure 1 the following, this method includes:

[0059] Step S11: When it is detected that the synthetic aperture radar satellite enters the preset monitoring range, determine the target synthetic aperture radar signal source and obtain the transmitted signal of the target synthetic aperture radar signal source.

[0060] First, perform real-time tracking and monitoring on the SAR satellite to determine whether it is necessary to collect its transmitted signal. It should be noted that when tracking the SAR satellite, analysis is carried out based on a pre-established private SAR satellite orbit database to improve the accuracy of detection and identification.

[0061] Specifically, obtain the two-line element (TLE) data of the SAR satellite, and use the two-line element data to determine the satellite trajectory of the synthetic aperture radar satellite. Among them, the satellite trajectory of the SAR satellite includes its orbital position and motion trajectory. In the embodiment of the present application, the SAR satellite is monitored in real time through an antenna, and the calculated satellite trajectory is compared with the antenna monitoring range to determine whether the satellite enters the monitoring range. If the satellite trajectory is within the preset monitoring range, it means that the SAR satellite enters the preset monitoring range, and it is necessary to further collect the corresponding transmitted signal; if the satellite trajectory of the SAR satellite is not within the preset monitoring range, no relevant operations need to be performed on the SAR satellite.

[0062] It should be noted that the antenna in the embodiment of the present application, as one of the signal receiving components, also has an automatic tracking function. When it is analyzed based on the pre-established private SAR satellite orbit database that the target satellite enters the monitoring range, for example, the 001SAR satellite enters the monitoring range of antenna A, then within the entire monitoring range, the antenna head of this antenna is automatically aligned to continuously track the satellite. In this way, it can ensure the monitoring of the satellite throughout its life cycle within the monitoring range.

[0063] Furthermore, for the SAR satellite that enters the preset monitoring range, determine the target SAR signal source. If the electromagnetic signal transmitted by the satellite is detected and received through the electromagnetic signal receiving device, it proves that the SAR satellite is powered on, and the current SAR satellite is used as the target SAR signal source, and the electromagnetic signal it transmits is the transmitted signal of the target SAR signal source. In this way, it gets rid of the dependence on the cooperation of the active signal, can passively receive the transmitted signal of the target SAR signal source, and realizes the evaluation of the working state of the signal source in a non-cooperative scenario.

[0064] It can be understood that currently, the evaluation of the working performance of SAR is limited to using the characteristics of echo signals. In the embodiments of the present application, after obtaining the transmitted signal of the target SAR signal source, corresponding processing is performed on the transmitted signal to convert it into an analog signal and a digital signal. The characteristic granularity of the analog signal and the digital signal is finer, more complete, and more comprehensive. Therefore, it can provide high-quality signal data for subsequent analysis. Specifically, analog processing is performed on the transmitted signal to convert the transmitted signal into a baseband signal; for example, after analog processing such as frequency conversion and amplification, the signal is converted into a baseband signal. Further, analog-to-digital conversion is performed on the baseband signal to generate the corresponding digital signal.

[0065] In a feasible implementation manner, in a non-cooperative scenario, more advanced devices can also be used to obtain echo signals, and then based on the transmitted signal and the echo signal for analysis, the working parameters and imaging performance of the signal source are obtained, further improving the system accuracy.

[0066] Step S12: Extract target characteristic parameters from the transmitted signal, and determine the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target characteristic parameters.

[0067] In the embodiments of the present application, features are extracted from the generated analog signal and digital signal after processing, and key characteristic parameters of the SAR signal are extracted therefrom, providing a basis for subsequent performance analysis. That is, feature extraction is respectively performed on the baseband signal and the digital signal to obtain the target characteristic parameters.

[0068] Specifically, when extracting the target characteristic parameters, the following steps are included:

[0069] 1) Perform real-time spectrum analysis on the transmitted signal based on digital radio frequency technology to extract the target frequency domain characteristics in the digital signal; for example, extract frequency domain characteristics such as the carrier frequency, chirp rate, and beam width of the signal.

[0070] 2) Perform time domain characteristic measurement on the transmitted signal based on pulse measurement technology to extract the target time domain characteristics in the digital signal; for example, extract time domain characteristics such as the pulse width, baseband signal bandwidth, and pulse duration.

[0071] 3) Analyze the antenna pattern to determine the target transmission characteristics of the transmitted signal, such as the antenna aperture size and beam distribution.

[0072] 4) Determine the target characteristic parameters of the transmitted signal based on the target frequency domain characteristics, target time domain characteristics, and target transmission characteristics.

[0073] Further, after extracting the target feature parameters, determine the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target feature parameters. Specifically, mainly analyze the target feature parameters through a mode classification algorithm, a multi-baseline analysis algorithm, and a polarization recognition algorithm to determine the working mode and imaging parameters of the target SAR signal source.

[0074] For example, analyze whether the SAR signal is single-baseline, multi-baseline, or has multi-view and multi-channel characteristics; judge the working band (such as X-band, C-band, etc.) and polarization mode of the SAR according to the spectral characteristics; classify the signal mode to judge whether it is a stripmap mode, a spotlight mode, an interferometric mode, or a fan-scan mode.

[0075] Step S13: Use the target feature parameters to update the spectral fingerprint of the target synthetic aperture radar signal source in real time, and evaluate the imaging ability of the echo signal of the target synthetic aperture radar signal source based on the spectral fingerprint, the target feature parameters, the working mode, and the imaging parameters to generate an imaging ability evaluation result.

[0076] In the embodiment of the present application, the spectral fingerprint of the target SAR signal source is generated in real time. The spectral fingerprint is generated after associating the target feature parameters with the identification information of the target SAR signal source. Specifically, it is to associate the signal source ID in the TLE data, quantify the extracted spectral features into a spectral fingerprint, and use it as the unique identifier of the target SAR signal source.

[0077] Further, all relevant data of the spectral fingerprint generated in real time will be recorded in a pre-constructed space target electromagnetic database to form a historical change trajectory based on the time dimension. Each evaluation is based on historical data and is continuously updated cumulatively using the target feature parameters. In this way, with the accumulation of data, based on the spectral fingerprint updated in real time, the imaging quality evaluation of the SAR will be more comprehensive and accurate, and each signal acquisition will enhance the evaluation of the working mode and imaging ability.

[0078] It should be noted that when evaluating the imaging ability of the echo signal of the target SAR signal source, the generated imaging ability evaluation result includes indicators such as resolution and coverage. In a specific implementation manner, the imaging resolution (azimuth and range) can be calculated by combining the target feature parameters of the transmitted signal; the coverage (the range of the surface area observable in each imaging), the imaging action distance, and the imaging processing time can be estimated by analyzing the orbit and antenna parameters; the imaging ability can be comprehensively evaluated by combining the signal-to-noise ratio, the imaging frequency (the time interval for the satellite to repeatedly observe the same area, also known as the revisit period), and the processing time to provide an estimated interval of performance indicators; an imaging probability value can be provided, etc.

[0079] The beneficial technical effects of the present application are as follows: First, when it is detected that the synthetic aperture radar satellite enters the monitoring range, the target synthetic aperture radar signal source is determined, realizing passive reception of the transmitted signal of the target synthetic aperture radar signal source in a non-cooperative scenario; Second, by analyzing the target feature parameters extracted from the transmitted signal, the working mode and imaging parameters of the target synthetic aperture radar signal source are determined, making the utilized feature granularity finer, more complete; Finally, the spectral fingerprint is updated in real time using the extracted target feature parameters, and the imaging ability of the echo signal is evaluated by combining the target feature parameters, working mode and imaging parameters to generate the final imaging ability evaluation result, making the imaging quality evaluation of the synthetic aperture radar more comprehensive and accurate. It can be seen that the present invention gets rid of the dependence on active signal cooperation; by inferring the working mode and imaging parameters of the signal source using the passively received transmitted signal, the imaging ability of the signal source can be estimated in the case of missing echo signals or inability to obtain imaging results; and it can cover the entire life cycle of data collection, analysis and evaluation, flexibly adapt, and provide wider applicability for the performance evaluation of the signal source.

[0080] Based on the above embodiments, in a feasible implementation manner, a space target electromagnetic database is constructed to store and manage the electromagnetic characteristics, spectral fingerprints and related historical data of the target SAR signal source signals, the working parameters of the SAR signal source and the imaging ability evaluation results. Specifically, the database design includes the following parts:

[0081] An electromagnetic characteristic table, a spectral fingerprint table, a time series table, a working parameter table and an imaging ability table are respectively set in the space target electromagnetic database;

[0082] Among them, the electromagnetic characteristic table is used to record the target feature parameters, such as characteristic data such as the carrier frequency, chirp rate, and bandwidth of the signal; the spectral fingerprint table is used to store the quantized spectral fingerprints of the signal; the time series table is used to record the time-dimensional change trajectory of the spectral characteristics of the transmitted signal; the working parameter table is used to store the working mode and imaging parameters of the target synthetic aperture radar signal source, and the imaging ability table is used to store the imaging ability evaluation results.

[0083] In the embodiment of the present application, the constructed space target electromagnetic database can also achieve the following functions:

[0084] 1) Real-time data update: After each signal analysis is completed, the SAR system will store the data required by each library table into the database to achieve real-time data update;

[0085] 2) Historical data query: Support historical data retrieval based on the time dimension or target characteristics;

[0086] 3) Comparison of target characteristics: Unknown targets can be identified or changes in target characteristics can be analyzed through spectrum fingerprint comparison.

[0087] Exemplarily, in combination with real-time updated spectrum fingerprints, the process of using the electromagnetic database of space targets is described. Specifically, the process of using the target feature parameters to update the spectrum fingerprint of the target synthetic aperture radar signal source in real time specifically includes the following steps:

[0088] Determine the identification information of the target synthetic aperture radar signal source according to the two-line orbital ephemeris data of the target synthetic aperture radar signal source;

[0089] Associate the target feature parameters with the identification information to generate the spectrum fingerprint of the target synthetic aperture radar signal source, and update the spectrum fingerprint in real time based on the time dimension change trajectory in the time series table.

[0090] In the embodiment of the present application, real-time spectrum analysis is performed on the transmitted signal of the received SAR signal source, and parameters such as frequency, power, bandwidth, and signal-to-noise ratio (SNR) are extracted. According to the TLE data of the target SAR signal source, its corresponding signal source ID can be determined, and the target feature parameters after spectrum feature extraction are associated to realize quantifying the extracted spectrum features into spectrum fingerprints as the unique identifier of the target signal source.

[0091] Since the real-time spectrum data will be stored in the electromagnetic database of space targets, a spectrum change trajectory in the time dimension will be formed and stored in the time series table. The spectrum fingerprint is updated in real time based on the time dimension change trajectory in the time series table. In this way, with the accumulation of data, the evaluation of the SAR working mode and imaging ability will become more comprehensive and accurate. Each evaluation is based on historical data, and each signal acquisition will enhance the evaluation ability.

[0092] As Figure 2 shown is a schematic diagram of an overall system working process provided in this embodiment based on the foregoing embodiment. Through real-time tracking, acquisition, feature extraction, spectrum fingerprint generation, and imaging ability analysis of the SAR transmitted signal, the imaging performance of the SAR satellite is comprehensively evaluated.

[0093] First, conduct real-time tracking and monitoring of the SAR satellite to determine whether it is necessary to collect its transmitted signal. In terms of technical implementation details, input: TLE orbit data, real-time antenna monitoring, and through key technologies: antenna coverage range and TLE matching algorithm, electromagnetic signal real-time detection algorithm, SAR signal recognition algorithm, etc., output: whether it enters the monitoring range (Boolean value), whether an electromagnetic signal is received (Boolean value). Then, conduct signal acquisition and preprocessing on the SAR signal source being tracked to provide high-quality signal data for subsequent analysis. That is, if an electromagnetic signal transmitted by the SAR satellite is received through an electromagnetic signal receiving device (such as an antenna and a radio frequency front end), complete the frequency conversion, amplification, and analog-to-digital conversion of the signal to generate analog and digital signals. In terms of technical implementation details, input: the transmitted signal of the target SAR signal source received, and through key technologies: radio frequency front-end design, multi-channel signal parallel acquisition technology, analog-to-digital conversion technology, etc., output: analog and digital signals after amplification, frequency conversion, and analog-to-digital conversion. It should be noted that the output signal data can be represented as Sti. For a multi-static SAR system, the transmitted signals of each base station can be recorded separately, numbered ST1, ST2, …, STn, where n is the number of base stations.

[0094] Furthermore, extract the key feature parameters of the SAR signal from the analog and digital signals. In terms of technical implementation details, input: the digital signal data Sti generated in the previous step, and through key technologies: spectrum analysis algorithm, pulse measurement technology, antenna parameter analysis algorithm, etc., output: the data of the target feature parameters corresponding to the SAR signal, including carrier frequency, chirp rate, bandwidth, pulse width, etc. Then, analyze the working mode and imaging parameters of the signal source in the SAR system according to the signal characteristics. In terms of technical implementation details, input: the data of the target feature parameters corresponding to the SAR signal, and through key technologies: mode classification algorithm, multi-baseline analysis algorithm, polarization recognition algorithm, etc., output: the analysis result of the SAR working parameters (polarization mode, mode classification, waveband, etc.). In a feasible implementation manner, more advanced algorithms can be used to replace the above signal analysis process. For example, use an artificial intelligence black box algorithm to evaluate the results from signal input to output and complete the end-to-end input and output.

[0095] Finally, the spectral fingerprint of the SAR signal is generated in real time and recorded in the database to form a historical change trajectory. In terms of technical implementation details, the input is the spectral data of the signal, and through key technologies such as real-time spectral analysis algorithm, spectral fingerprint generation algorithm, and database storage technology, the output is the spectral fingerprint data and its historical change trajectory. In a feasible implementation manner, when generating the spectral fingerprint, an artificial intelligence-based signal classification and analysis algorithm can also be added. Then, the imaging ability of its echo is evaluated based on the spectral fingerprint with historical data, SAR signal characteristics, and working parameters. In terms of technical implementation details, the input is SAR signal characteristic data and working parameters, and through key technologies such as TLE orbit calculation, imaging geometry modeling, and resolution calculation formula, the output is the imaging ability evaluation result (resolution, coverage, revisit period, imaging probability, etc.).

[0096] As Figure 3 shown is an exemplary evaluation system for the working parameters of a signal source and the echo imaging performance based on the passive SAR transmitted signal in a non-cooperative scenario. Through modular design, the entire process coverage from signal detection to imaging performance evaluation is achieved. The system includes three main modules: a signal acquisition and processing system, a signal analysis system, and a performance evaluation system. Each module realizes the layer-by-layer processing of data through internal functional units, and finally outputs the working parameters of the signal source, spectral fingerprint, and imaging ability evaluation result. The functions of each module are clear and closely connected, and can efficiently complete the whole process from monitoring range judgment, signal acquisition, feature extraction to imaging ability evaluation, ensuring the real-time and accuracy of the system.

[0097] 1) Signal acquisition and processing system: Responsible for satellite orbit calculation and signal reception; judge whether the satellite enters the monitoring range and whether a signal is received; if the satellite is within the monitoring range and there is a signal, receive the transmitted signal of the target SAR signal source, complete the frequency conversion, amplification, and analog-to-digital conversion of the signal, and generate corresponding analog and digital signals.

[0098] 2) Signal analysis system: Extract key characteristic parameters (such as carrier frequency, chirp rate, bandwidth, modulation mode, beam width, etc.) from the collected analog and digital signals, analyze the working mode of the SAR system (such as working band, polarization mode, transmit frequency range, multi-mode characteristics, etc.) according to the extracted signal characteristics, and store the signal characteristics and analysis results in the database.

[0099] 3) Performance evaluation system: Associate the signal source ID in the TLE data, quantify the spectral characteristics of the target signal into a spectral fingerprint, and store it in the space target electromagnetic database in real time to form a historical change trajectory. Combine the spectral fingerprint with the analysis results of the signal source working parameters and signal characteristic data in the signal analysis system to evaluate the imaging ability of the SAR system, including performance indicators such as resolution, coverage, and revisit period.

[0100] It can be seen that, different from the traditional method of evaluating imaging quality relying on echo signals, the present invention focuses on analyzing the characteristics of SAR transmitted signals. By extracting its key parameters (such as carrier frequency, bandwidth, modulation mode, etc.), it realizes a comprehensive evaluation of the working state and potential imaging performance of the signal source in a non-cooperative scenario, overcoming the limitations of the prior art's dependence on active signal cooperation and echo imaging. Starting from the analysis of the SAR satellite TLE orbit data, the entire process design from determining whether the signal source enters the monitoring range, signal source signal acquisition, feature extraction, working parameter analysis, imaging ability evaluation to finally generating a spectral fingerprint and updating the space target electromagnetic database covers the entire life cycle of data acquisition, analysis, and evaluation. The present invention does not rely on the active cooperation of the signal source. Based on the characteristics of the SAR transmitted signal, through a complete performance evaluation system, it can estimate the imaging ability (such as resolution, signal-to-noise ratio, coverage range, etc.) of the signal source in the case of missing echo signals or unable to obtain imaging results, and realizes real-time monitoring and evaluation of unknown SAR signal sources in complex non-cooperative scenarios (such as space target monitoring or analysis of unknown SAR signal sources).

[0101] Correspondingly, an embodiment of the present application also discloses an imaging quality evaluation device for a synthetic aperture radar. Refer to Figure 4 As shown, the device includes:

[0102] A signal acquisition module 11, configured to determine a target synthetic aperture radar signal source and obtain the transmitted signal of the target synthetic aperture radar signal source when it is detected that the synthetic aperture radar satellite enters a preset monitoring range;

[0103] A signal analysis module 12, configured to extract target feature parameters from the transmitted signal and determine the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target feature parameters;

[0104] A performance evaluation module 13, configured to use the target feature parameters to update the spectral fingerprint of the target synthetic aperture radar signal source in real time, and evaluate the imaging ability of the echo signal of the target synthetic aperture radar signal source based on the spectral fingerprint, the target feature parameters, the working mode, and the imaging parameters to generate an imaging ability evaluation result; wherein, the spectral fingerprint is a feature generated by associating the target feature parameters with the identification information of the target synthetic aperture radar signal source and can be continuously accumulated and updated based on historical data.

[0105] Among them, for the more specific working processes of the above-mentioned various modules, reference can be made to the corresponding content disclosed in the foregoing embodiments, and details will not be elaborated herein.

[0106] It can be seen that, through the above solution of this embodiment, when it is monitored that the synthetic aperture radar satellite enters the preset monitoring range, the target synthetic aperture radar signal source is determined, and the transmitted signal of the target synthetic aperture radar signal source is acquired; the target characteristic parameters are extracted from the transmitted signal, and the working mode and imaging parameters of the target synthetic aperture radar signal source are determined according to the target characteristic parameters; the spectral fingerprint of the target synthetic aperture radar signal source is updated in real time by using the target characteristic parameters, and the imaging ability of the echo signal of the target synthetic aperture radar signal source is evaluated based on the spectral fingerprint, the target characteristic parameters, the working mode and the imaging parameters to generate an imaging ability evaluation result; wherein, the spectral fingerprint is generated by associating the target characteristic parameters with the identification information of the target synthetic aperture radar signal source, and is a characteristic that can be continuously accumulated and updated based on historical data.

[0107] The beneficial technical effects of this application are as follows: First, when it is monitored that the synthetic aperture radar satellite enters the monitoring range, the target synthetic aperture radar signal source is determined, realizing passive reception of the transmitted signal of the target synthetic aperture radar signal source in a non-cooperative scenario; Second, by analyzing the target characteristic parameters extracted from the transmitted signal, the working mode and imaging parameters of the target synthetic aperture radar signal source are determined, making the utilized characteristic granularity finer, more comprehensive and more complete; Finally, the spectral fingerprint is updated in real time by using the extracted target characteristic parameters, and the imaging ability of the echo signal is evaluated in combination with the target characteristic parameters, the working mode and the imaging parameters to generate the final imaging ability evaluation result, making the imaging quality evaluation of the synthetic aperture radar more comprehensive and accurate. It can be seen that the present invention gets rid of the dependence on active signal cooperation; by using the passively received transmitted signal to infer the working mode and imaging parameters of the signal source, the imaging ability of the signal source can be estimated in the case of missing echo signals or unable to obtain imaging results; and it can cover the entire life cycle of data collection, analysis and evaluation, flexibly adapt, and provide wider applicability for the performance evaluation of the signal source.

[0108] Furthermore, the embodiment of this application also discloses an electronic device Figure 5 It is a structural diagram of an electronic device 20 shown according to an exemplary embodiment, and the content in the figure cannot be considered as any limitation on the scope of use of this application.

[0109] Figure 5Schematic diagram of the structure of an electronic device 20 provided by an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. Among them, the memory 22 is used to store a computer program, and the computer program is loaded and executed by the processor 21 to implement the relevant steps in the synthetic aperture radar imaging quality evaluation method disclosed in any of the foregoing embodiments.

[0110] In this embodiment, the power supply 23 is used to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows is any communication protocol applicable to the technical solution of the present application, and no specific limitation is imposed here; the input / output interface 25 is used to obtain external input data or output data to the outside, and its specific interface type can be selected according to specific application needs, and no specific limitation is made here.

[0111] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, a random access memory, a magnetic disk, or an optical disc, etc. The resources stored thereon can include an operating system 221, a computer program 222, and data 223, etc. The data 223 can include various kinds of data. The storage method can be temporary storage or permanent storage.

[0112] Among them, the operating system 221 is used to manage and control each hardware device and the computer program 222 on the electronic device 20, and it can be Windows Server, Netware, Unix, Linux, etc. In addition to the computer program that can be used to complete the synthetic aperture radar imaging quality evaluation method executed by the electronic device 20 disclosed in any of the foregoing embodiments, the computer program 222 can further include computer programs that can be used to complete other specific tasks.

[0113] Furthermore, an embodiment of the present application also discloses a computer-readable storage medium. The computer-readable storage medium mentioned here includes a random access memory (Random Access Memory, RAM), memory, read-only memory (Read-Only Memory, ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, magnetic disks, or optical discs, or any other form of storage medium well-known in the technical field. Among them, when the computer program is executed by the processor, it implements the foregoing synthetic aperture radar imaging quality evaluation method. For the specific steps of this method, reference can be made to the corresponding content disclosed in the foregoing embodiments, and details are not described herein again.

[0114] In the present specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section.

[0115] The steps of the synthetic aperture radar imaging quality evaluation method or algorithm described in combination with the embodiments disclosed herein can be directly implemented by hardware, software modules executed by a processor, or a combination of both. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0116] Finally, it should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the element.

[0117] The above has introduced in detail a synthetic aperture radar imaging quality evaluation method, device, equipment and medium provided by the present invention. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A synthetic aperture radar imaging quality assessment method, characterized in that: include: When it is monitored that a synthetic aperture radar satellite enters a preset monitoring range, a target synthetic aperture radar signal source is determined, and a transmission signal of the target synthetic aperture radar signal source is acquired; Extracting target characteristic parameters from the transmission signal, and determining the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target characteristic parameters; The spectrum fingerprint of the target synthetic aperture radar signal source is updated in real time by using the target characteristic parameter, and the imaging capability of the echo signal of the target synthetic aperture radar signal source is evaluated based on the spectrum fingerprint, the target characteristic parameter, the working mode and the imaging parameter to generate an imaging capability evaluation result; wherein the spectrum fingerprint is generated by associating the target characteristic parameter with the identification information of the target synthetic aperture radar signal source, and can be continuously accumulated and updated based on historical data; The method of using the target characteristic parameter to update the spectrum fingerprint of the target synthetic aperture radar signal source in real time includes: Determining identification information of the target synthetic aperture radar signal source according to the dual-row orbit ephemeris data of the target synthetic aperture radar signal source; The target characteristic parameter is associated with the identification information to generate a spectrum fingerprint of the target synthetic aperture radar signal source, and the spectrum fingerprint is updated in real time based on the time dimension change trajectory in the time series table.

2. The imaging quality assessment method of synthetic aperture radar according to claim 1, characterized in that: When the synthetic aperture radar satellite is monitored to enter the preset monitoring range, determining the target synthetic aperture radar signal source and acquiring the transmission signal of the target synthetic aperture radar signal source include: Acquiring dual-row orbit ephemeris data of the synthetic aperture radar satellite, and determining the satellite trajectory of the synthetic aperture radar satellite using the dual-row orbit ephemeris data; Performing real-time monitoring of the synthetic aperture radar satellite via an antenna to determine whether the satellite trajectory is within the preset monitoring range; When the satellite trajectory is within the preset monitoring range, determining that the synthetic aperture radar satellite enters the preset monitoring range; When the electromagnetic signal transmitted by the synthetic aperture radar satellite is received by the electromagnetic signal receiving device within the preset monitoring range, the current synthetic aperture radar satellite is determined as the target synthetic aperture radar signal source, and the electromagnetic signal is used as the transmission signal of the target synthetic aperture radar signal source.

3. The imaging quality assessment method of synthetic aperture radar according to claim 1, characterized in that: After acquiring the transmission signal of the target synthetic aperture radar signal source, the method further includes: Performing analog processing on the transmit signal to convert the transmit signal into a baseband signal; Performing analog-to-digital conversion on the baseband signal to generate a corresponding digital signal; Accordingly, extracting target characteristic parameters from the transmission signal includes: Feature extraction is performed on the baseband signal and the digital signal respectively to obtain the target feature parameters.

4. The imaging quality assessment method of synthetic aperture radar according to claim 1, characterized in that: The step of extracting target characteristic parameters from the transmitted signal comprises: Performing real-time spectrum analysis on the transmitted signal based on digital radio frequency technology to extract target frequency domain features in the digital signal; Performing time domain feature measurement on the transmission signal based on a pulse measurement technique to extract target time domain features in the digital signal; Analyzing the antenna pattern to determine target transmission characteristics of the transmitted signal; The target characteristic parameters of the transmission signal are determined based on the target frequency domain characteristics, the target time domain characteristics and the target transmission characteristics.

5. The imaging quality assessment method of synthetic aperture radar according to claim 1, characterized in that: The step of determining the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target characteristic parameters includes: The target characteristic parameters are analyzed respectively by a pattern classification algorithm, a multi-baseline analysis algorithm and a polarization recognition algorithm to determine the working mode and imaging parameters of the target synthetic aperture radar signal source.

6. The method for evaluating the imaging quality of synthetic aperture radar according to any one of claims 1 to 5, characterized in that: Also includes: Constructing a space target electromagnetic database, and respectively setting an electromagnetic feature table, a spectrum fingerprint table, a time series table, a working parameter table, and an imaging capability table in the space target electromagnetic database; Among them, the electromagnetic characteristic table is used to record the target characteristic parameters, the spectrum fingerprint table is used to store the spectrum fingerprint, the time series table is used to record the time dimension change trajectory of the spectrum characteristics of the transmitted signal, the working parameter table is used to store the working mode and imaging parameters of the target synthetic aperture radar signal source, and the imaging capability table is used to store the imaging capability evaluation result.

7. A synthetic aperture radar imaging quality assessment device, characterized in that: include: A signal acquisition module, used to determine a target synthetic aperture radar signal source and acquire a transmission signal of the target synthetic aperture radar signal source when a synthetic aperture radar satellite is detected to enter a preset monitoring range; A signal analysis module, used to extract target characteristic parameters from the transmission signal, and determine the working mode and imaging parameters of the target synthetic aperture radar signal source according to the target characteristic parameters; a performance evaluation module, configured to update the spectrum fingerprint of the target synthetic aperture radar signal source in real time by using the target characteristic parameter, and to evaluate the imaging capability of the echo signal of the target synthetic aperture radar signal source based on the spectrum fingerprint, the target characteristic parameter, the working mode and the imaging parameter, so as to generate an imaging capability evaluation result; wherein the spectrum fingerprint is generated by associating the target characteristic parameter with the identification information of the target synthetic aperture radar signal source, and is a feature that can be continuously accumulated and updated based on historical data; The method of using the target characteristic parameter to update the spectrum fingerprint of the target synthetic aperture radar signal source in real time includes: Determining identification information of the target synthetic aperture radar signal source according to the dual-row orbit ephemeris data of the target synthetic aperture radar signal source; The target characteristic parameter is associated with the identification information to generate a spectrum fingerprint of the target synthetic aperture radar signal source, and the spectrum fingerprint is updated in real time based on the time dimension change trajectory in the time series table.

8. An electronic device, characterized in that: The electronic device includes a processor and a memory; wherein the memory is used to store a computer program, and the computer program is loaded and executed by the processor to implement the imaging quality assessment method of the synthetic aperture radar as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: Used to store computer programs; wherein when the computer program is executed by a processor, the imaging quality assessment method of a synthetic aperture radar as described in any one of claims 1 to 6 is implemented.

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