Scene matching guidance system based on miniature synthetic aperture radar

Abstract

The invention relates to the technical field of radar data processing, and discloses a scene matching guidance system based on a miniature synthetic aperture radar, which comprises a multi-dimensional acquisition module and an intelligent matching module. According to the system, SAR image data of all target areas and SAR image data provided by echo signals in real time are acquired through a multi-dimensional acquisition module and are classified to form a data set, the multi-dimensional acquisition module performs standardization processing and analysis on the data set to generate a digital elevation model, an intelligent matching module analyzes the authenticity of SAR images of each target area, and the authenticity of the SAR images of each target area is analyzed. The method comprises the following steps: generating a corresponding credible index, setting a monitoring period with a fixed time length, analyzing a fluctuation index of real-time signal intensity and a matching index of an SAR image, quantifying data quality and matching potential, dynamically monitoring high image precision, setting a fluctuation threshold value by an intelligent matching module, judging whether the SAR image has a delay problem or not, and judging whether the SAR image has a delay problem or not. And scene matching guidance and track synchronization are carried out according to the credibility index, the matching index and the digital elevation model, and the scene matching guidance is high in applicability.

Description

Technical Field

[0001] The invention relates to the technical field of radar data processing, in particular to a scene matching guidance system based on a miniature synthetic aperture radar. Background Art

[0002] Micro-SAR is a miniaturized SAR system that is suitable for aircraft, missiles, small satellites, vehicles or other mobile devices by reducing system size, cost and power consumption. Despite its miniature size, SAR technology still has high resolution and can synthesize a long effective beam, thus achieving high-resolution imaging capabilities. Micro-SAR transmits microwave signals to the target area through the radar host. These signals will be reflected back after encountering the target. The radar antenna records the echo signals reflected back from different positions in turn, and then simulates large-aperture antenna imaging based on the phase and amplitude information of these signals using the relative motion between the target and the radar. Range focusing is to determine the distance of the target by analyzing the delay information in the echo signal, that is, to calculate the distance between the target and the radar based on the time it takes for the signal to be transmitted from the radar to be received. Azimuth focusing uses the Doppler effect generated by the relative motion between the radar and the target to determine the position of the target in azimuth based on the Doppler frequency shift. By focusing the information in these two directions, a high-resolution two-dimensional image of the target is finally obtained. In actual use, the frequency bands of microwave signals emitted by the micro synthetic aperture radar cover multiple bands such as Ku, X, L, Ka, and W, which can meet the needs of different application scenarios. It is also equipped with an advanced data processing system that can process and analyze monitoring data in real time, and then transmit it to the ground station or command center in real time through the communication system. This provides decision makers with timely and accurate positioning information, which helps to better guide actions.

[0003] At present, the scene matching guidance system of traditional micro-synthetic aperture radar mainly relies on static data for analysis. This method is easily affected by various factors such as atmospheric interference, resulting in low guidance efficiency and poor accuracy. In addition, the traditional system adopts a single matching mechanism, which is difficult to adapt to rapidly changing scenes and has low reference value in actual use. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a scene matching guidance system based on a miniature synthetic aperture radar, which has the advantages of high dynamic monitoring image accuracy and strong applicability of scene matching guidance, and solves the problems of low efficiency, poor accuracy and low reference value of the scene matching guidance system of the traditional miniature synthetic aperture radar.

[0005] (II) Technical solution To achieve the above object, the present invention provides the following technical solutions: A scene matching guidance system based on a miniature synthetic aperture radar comprises a multi-dimensional acquisition module and an intelligent matching module; The multi-dimensional acquisition module is composed of a reference image unit, a radar image unit and a pre-processing unit. The reference image unit is connected to a mapping satellite through a network to collect a reference data set, and the reference data set includes SAR image data of all target areas. The radar image unit is connected to a micro synthetic aperture radar through a network to collect a real-time data set, and the real-time data set includes SAR image data provided in real time by an echo signal. The pre-processing unit performs standardization processing on the reference data set and the real-time data set, and analyzes and generates a digital elevation model. and transmitted to the intelligent matching module through the network; The intelligent matching module consists of an image evaluation unit, a real-time analysis unit and a scene matching unit. The image evaluation unit analyzes the authenticity of each target area SAR image based on the reference data set and generates a corresponding credibility index. The real-time analysis unit is provided with a monitoring cycle of fixed duration. , combined with the real-time data set, analyze the fluctuation index of real-time signal strength Matching index with SAR image The scene matching unit is provided with a fixed range of fluctuation thresholds. , combined with the volatility index , determine whether there is a delay problem in the SAR image, and then use the credibility index , Matching Index , Digital Elevation Model Perform scene matching guidance and synchronized track.

[0006] Preferably, the expression of the reference data set is , to Indicates the first target area to the The SAR image data of the target area includes the echo signal strength, ground distance, slant range and overlap area. Represents the area of ​​a single target region.

[0007] Preferably, the expression of the real-time data set is , to Indicates the echo signal from the first to the The SAR image data provided by the echo signal includes real-time signal strength, azimuth resolution, range resolution and signal-to-noise ratio. Indicates the time point at which the echo signal SAR image data is acquired.

[0008] Preferably, the standardization process is as follows: The meteorological parameters of all target areas are collected through the network connection big data platform, including temperature, air pressure, wind speed, wind direction, aerosol mass concentration and atmospheric stratification stability; The MODTRAN atmospheric radiation transfer model is used to input the meteorological parameters of all target areas, remove the noise of signal attenuation and phase delay, and eliminate the atmospheric distortion of SAR images in the reference dataset and real-time dataset.

[0009] Preferably, the digital elevation model The analysis process is as follows: Collect geographic information of all target areas through network connection to the big data platform, including latitude and longitude coordinates, altitude, location identifier and topography; Use image processing software to combine the geographic information of all target areas with the standardized reference dataset to create a digital elevation model , which is used to eliminate the geometric distortion problem of SAR images in reference datasets and real-time datasets.

[0010] Preferably, the credibility index The calculation process is as follows: According to the reference data set, extract the SAR image data of the target area, and the The signal strength of the callback signal in the target area is marked as , will The ground distance of the target area is marked as , will The slope range of the target area is marked as , will The overlapping area of ​​the target area is marked as , will The area of ​​the target region is marked as , ; In the formula, Represents the weight for the echo signal strength, represents the weight for the ratio of ground distance to slope distance, Represents the weight of the ratio of the overlap area to the target area. , and are constants, and , Indicates according to , and Weight, calculate the Credibility index of target area .

[0011] Preferably, the volatility index The calculation process is as follows: Statistical monitoring cycle based on real-time data sets The real-time signal strength within is marked as , to Indicates the first to Provides real-time signal strength of SAR image data; ; In the formula, Indicates monitoring cycle The average value of real-time signal strength, Indicates Provides real-time signal strength of SAR image data, , Indicates that the monitoring period is calculated according to the standard deviation formula Real-time signal strength fluctuation index .

[0012] Preferably, the matching index The calculation process is as follows: According to the real-time data set, extract the echo signal The SAR image data provided by The azimuth resolution of the secondary SAR image is marked as , will The range resolution of the secondary SAR image is marked as , will The signal-to-noise ratio of the secondary SAR image is marked as ; ; In the formula, represents the weight for azimuth resolution, represents the weight for the range resolution, represents the weight for the signal-to-noise ratio, , and are constants, and , Indicates according to , and Weight, calculate the Matching index of sub-SAR images .

[0013] Preferably, the volatility index Exceeding the volatility threshold , it means that there is a delay problem in the SAR image. It is recommended to adjust the time difference before performing scene matching guidance.

[0014] Preferably, the scene matching unit is based on the credibility index Arrange the target area from high to low, the volatility index Included in volatility threshold When the matching index is given priority High SAR image and credibility index The high target area is image matched for guidance, and based on the matching results, the digital elevation model is used to Synchronous track.

[0015] Compared with the prior art, the present invention provides a scene matching guidance system based on a micro synthetic aperture radar, which has the following beneficial effects: 1. The present invention connects the surveying and mapping satellite and the micro synthetic aperture radar through a multi-dimensional acquisition module network, obtains the SAR image data of all target areas and the SAR image data provided by the echo signal in real time, and classifies them into a reference data set and a real-time data set. The multi-dimensional acquisition module uses the MODTRAN atmospheric radiation transmission model to input the meteorological parameters of all target areas, removes the noise of signal attenuation and phase delay, eliminates the distortion problem of the atmosphere on the SAR images in the reference data set and the real-time data set, and uses image processing software to combine the geographic information of all target areas and the reference data set after standardization to establish a digital elevation model. , which is used to eliminate the geometric distortion problem of SAR images in the reference data set and the real-time data set, and significantly improve the authenticity and consistency of SAR images. The intelligent matching module analyzes the authenticity of the SAR image of each target area according to the reference data set and generates the corresponding credibility index , set a fixed-length monitoring cycle , and then analyze the fluctuation index of real-time signal strength Matching index with SAR image ,quantify data quality and matching potential, and achieve high accuracy in dynamic monitoring images.

[0016] 2. The present invention sets a fixed range of fluctuation thresholds through the intelligent matching module , determine whether there is a delay problem in the SAR image, fluctuation index Exceeding the volatility threshold , it indicates that there is a delay problem in the SAR image. It is recommended to adjust the time difference before performing image matching guidance to avoid mismatching due to unstable data. The image matching unit is based on the credibility index. Arrange target areas from high to low, volatility index Included in volatility threshold When the matching index is given priority High SAR image and credibility index The high target area is image matched for guidance, which effectively improves the guidance accuracy, and based on the matching results, the digital elevation model is used to The synchronized track and scene matching guidance are highly applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of the system of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Since the traditional micro-synthetic aperture radar scene matching guidance system mainly relies on static data for analysis, this method is easily affected by various factors such as atmospheric interference, resulting in low guidance efficiency and poor accuracy. In addition, the traditional system uses a single matching mechanism, which is difficult to adapt to rapidly changing scenes and has low reference value in actual use. Therefore, a scene matching guidance system based on micro-synthetic aperture radar is provided. Please refer to Figure 1 , a scene matching guidance system based on a micro synthetic aperture radar, including a multi-dimensional acquisition module and an intelligent matching module; The multi-dimensional acquisition module consists of a reference image unit, a radar image unit and a preprocessing unit. The reference image unit collects a reference data set through a network connection to a mapping satellite. The reference data set includes SAR image data of all target areas. The expression of the reference data set is: , to Indicates the first target area to the The SAR image data of the target area includes the echo signal strength, ground distance, slant range and overlap area. Represents the area of ​​a single target region; The radar scene unit is connected to the micro synthetic aperture radar through the network to collect real-time data sets. The real-time data sets include SAR image data provided by the echo signal in real time. The expression of the real-time data set is: , to Indicates the echo signal from the first to the The SAR image data provided by the echo signal includes real-time signal strength, azimuth resolution, range resolution and signal-to-noise ratio. It indicates the time point when the echo signal SAR image data is obtained, covering the static geographic information and dynamic real-time signal of the target area. The combination of the two can comprehensively characterize the electromagnetic characteristics and geometric features of the target area; The preprocessing unit performs standardization processing on the reference data set and the real-time data set, and analyzes and generates a digital elevation model. and transmitted to the intelligent matching module through the network; The standardized processing flow is as follows: The meteorological parameters of all target areas are collected through the network connection big data platform, including temperature, air pressure, wind speed, wind direction, aerosol mass concentration and atmospheric stratification stability; Using the MODTRAN atmospheric radiation transfer model, the meteorological parameters of all target areas are input to remove the noise of signal attenuation and phase delay, and eliminate the atmospheric distortion of SAR images in the reference data set and real-time data set; Digital Elevation Model The analysis process is as follows: Collect geographic information of all target areas through network connection to the big data platform, including latitude and longitude coordinates, altitude, location identifier and topography; Use image processing software to combine the geographic information of all target areas with the standardized reference dataset to create a digital elevation model , used to eliminate the geometric distortion problem of SAR images in reference data sets and real-time data sets, and significantly improve the authenticity and consistency of SAR images; The intelligent matching module consists of an image evaluation unit, a real-time analysis unit, and a scene matching unit. The image evaluation unit analyzes the authenticity of the SAR image of each target area based on the reference data set and generates a corresponding credibility index. , Trust Index The calculation process is as follows: According to the reference data set, extract the SAR image data of the target area, and the The signal strength of the callback signal in the target area is marked as , will The ground distance of the target area is marked as , will The slope range of the target area is marked as , will The overlapping area of ​​the target area is marked as , will The area of ​​the target region is marked as , ; In the formula, Represents the weight for the echo signal strength, represents the weight for the ratio of ground distance to slope distance, Represents the weight of the ratio of the overlap area to the target area. , and are constants, and , Indicates according to , and Weight, calculate the Credibility index of target area , and so on, each target area has a corresponding credibility index , ensuring the balance of subsequent evaluation results; The real-time analysis unit is set with a fixed-length monitoring cycle , combined with the real-time data set, analyze the fluctuation index of real-time signal strength Matching index with SAR image ; Volatility Index The calculation process is as follows: Statistical monitoring cycle based on real-time data sets The real-time signal strength within is marked as , to Indicates the first to Provides real-time signal strength of SAR image data; ; In the formula, Indicates monitoring cycle The average value of real-time signal strength, Indicates Provides real-time signal strength of SAR image data, , Indicates that the monitoring period is calculated according to the standard deviation formula Real-time signal strength fluctuation index , volatility index The smaller it is, the more stable the echo signal is and the better the SAR image quality is. Matching Index The calculation process is as follows: According to the real-time data set, extract the echo signal The SAR image data provided by The azimuth resolution of the secondary SAR image is marked as , will The range resolution of the secondary SAR image is marked as , will The signal-to-noise ratio of the secondary SAR image is marked as ; ; In the formula, represents the weight for azimuth resolution, represents the weight for the range resolution, represents the weight for the signal-to-noise ratio, , and are constants, and , Indicates according to , and Weight, calculate the Matching index of sub-SAR images ,quantify data quality and matching potential, high accuracy of dynamic monitoring images; The scene matching unit is set with a fixed range of fluctuation thresholds , determine whether there is a delay problem in the SAR image, fluctuation index Exceeding the volatility threshold , it indicates that there is a delay problem in the SAR image. It is recommended to adjust the time difference before performing image matching guidance to avoid mismatching due to unstable data. The image matching unit is based on the credibility index. Arrange target areas from high to low, volatility index Included in volatility threshold When the matching index is given priority High SAR image and credibility index The high target area is image matched for guidance, which effectively improves the guidance accuracy, and based on the matching results, the digital elevation model is used to Specifically, in the application scenario of disaster monitoring, the synchronized track is preferentially matched with areas with stable terrain and high signal-to-noise ratio, which can ensure the credibility of disaster assessment. In the application scenario of military navigation, the flight path with minimal geometric distortion and stable real-time signal can be preferentially selected, and the image matching guidance is highly applicable.

[0020] Example 1: In this experiment, a drone equipped with a micro synthetic aperture radar was selected as the experimental object. According to statistics, within 5 minutes, the real-time signal strength of the SAR image data provided by the 5 echo signals was 4V, 8V, 6V, 5V and 7V respectively. The fluctuation index of the SAR image data of the drone was The calculation process is as follows: ; In the formula, Indicates the average value of real-time signal strength within 5 minutes. Indicates the real-time signal strength of the SAR image data provided for the first time. According to the standard deviation formula, the fluctuation index of the UAV SAR image data within 5 minutes is calculated. is 2V, the fluctuation threshold Set to 1~5V, it is judged that the fluctuation index of the drone SAR image data Included in volatility threshold SAR images do not have a delay problem, and the matching index is preferred High SAR image and credibility index The high target area is image matched for guidance, and based on the matching results, the digital elevation model is used to Synchronous track.

[0021] Example 2: In this experiment, an aircraft equipped with a micro synthetic aperture radar is selected as the experimental object. After monitoring, the aircraft has received 3 groups of SAR image data provided by the echo signal. Among them, the azimuth resolution of the first group of SAR images is 0.5 meters, the range resolution is 1.0 meters, the signal-to-noise ratio is 20 dB, and the matching index of the first group of SAR image data is The calculation process is as follows: ; In the formula, represents the weight for azimuth resolution, represents the weight for the range resolution, represents the weight for the signal-to-noise ratio, , and are constants, and ,according to , and Weight, calculate the matching index of the first set of SAR image data is 6.5. For this pair, the matching index of the second set of SAR image data is The matching index of the third set of SAR image data is 5.5. is 5.0, after judgment, the matching index is preferred The first set of SAR image data with a credibility index of 6.5 The high target area is image matched for guidance, and based on the matching results, the digital elevation model is used to Synchronous track.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A scene matching guidance system based on a micro synthetic aperture radar, characterized in that: Including multi-dimensional acquisition module and intelligent matching module; The multi-dimensional acquisition module is composed of a reference image unit, a radar image unit and a pre-processing unit. The reference image unit is connected to a mapping satellite through a network to collect a reference data set, and the reference data set includes SAR image data of all target areas. The radar image unit is connected to a micro synthetic aperture radar through a network to collect a real-time data set, and the real-time data set includes SAR image data provided in real time by an echo signal. The pre-processing unit performs standardization processing on the reference data set and the real-time data set, and analyzes and generates a digital elevation model. and transmitted to the intelligent matching module through the network; The intelligent matching module consists of an image evaluation unit, a real-time analysis unit and a scene matching unit. The image evaluation unit analyzes the authenticity of each target area SAR image based on the reference data set and generates a corresponding credibility index. The real-time analysis unit is provided with a monitoring cycle of fixed duration. , combined with the real-time data set, analyze the fluctuation index of real-time signal strength Matching index with SAR image The scene matching unit is provided with a fixed range of fluctuation thresholds. , combined with the volatility index , determine whether there is a delay problem in the SAR image, and then use the credibility index , Matching Index , Digital Elevation Model Perform scene matching guidance and synchronized track.

2. The scene matching guidance system based on micro synthetic aperture radar according to claim 1, characterized in that: The expression of the reference data set is , to Indicates the first target area to the The SAR image data of the target area includes the echo signal strength, ground distance, slant range and overlap area. Represents the area of ​​a single target region.

3. The scene matching guidance system based on micro synthetic aperture radar according to claim 2 is characterized in that: The expression of the real-time data set is: , to Indicates the echo signal from the first to the The SAR image data provided by the echo signal includes real-time signal strength, azimuth resolution, range resolution and signal-to-noise ratio. Indicates the time point at which the echo signal SAR image data is acquired.

4. The scene matching guidance system based on micro synthetic aperture radar according to claim 3 is characterized in that: The standardized processing flow is as follows: The meteorological parameters of all target areas are collected through the network connection big data platform, including temperature, air pressure, wind speed, wind direction, aerosol mass concentration and atmospheric stratification stability; The MODTRAN atmospheric radiation transfer model is used to input the meteorological parameters of all target areas, remove the noise of signal attenuation and phase delay, and eliminate the atmospheric distortion of SAR images in the reference dataset and real-time dataset.

5. The scene matching guidance system based on micro synthetic aperture radar according to claim 4 is characterized in that: The digital elevation model The analysis process is as follows: Collect geographic information of all target areas through network connection to the big data platform, including latitude and longitude coordinates, altitude, location identifier and topography; Use image processing software to combine the geographic information of all target areas with the standardized reference dataset to create a digital elevation model , which is used to eliminate the geometric distortion problem of SAR images in reference datasets and real-time datasets.

6. The scene matching guidance system based on micro synthetic aperture radar according to claim 5 is characterized in that: The credibility index The calculation process is as follows: According to the reference data set, extract the SAR image data of the target area, and the The signal strength of the callback signal in the target area is marked as , will The ground distance of the target area is marked as , will The slope range of the target area is marked as , will The overlapping area of ​​the target area is marked as , will The area of ​​the target region is marked as , ； In the formula, Represents the weight for the echo signal strength, represents the weight for the ratio of ground distance to slope distance, Represents the weight of the ratio of the overlap area to the target area. , and are constants, and , Indicates according to , and Weight, calculate the Credibility index of target area .

7. The scene matching guidance system based on micro synthetic aperture radar according to claim 6 is characterized in that: The volatility index The calculation process is as follows: Statistical monitoring cycle based on real-time data sets The real-time signal strength within is marked as , to Indicates the first to Provides real-time signal strength of SAR image data; ； In the formula, Indicates monitoring cycle The average value of real-time signal strength, Indicates Provides real-time signal strength of SAR image data, , Indicates that the monitoring period is calculated according to the standard deviation formula Real-time signal strength fluctuation index .

8. The scene matching guidance system based on micro synthetic aperture radar according to claim 7 is characterized in that: The matching index The calculation process is as follows: According to the real-time data set, extract the echo signal The SAR image data provided by The azimuth resolution of the secondary SAR image is marked as , will The range resolution of the secondary SAR image is marked as , will The signal-to-noise ratio of the secondary SAR image is marked as ; ； In the formula, represents the weight for azimuth resolution, represents the weight for the range resolution, represents the weight for the signal-to-noise ratio, , and are constants, and , Indicates according to , and Weight, calculate the Matching index of sub-SAR images .

9. The scene matching guidance system based on micro synthetic aperture radar according to claim 8, characterized in that: The volatility index Exceeding the volatility threshold , it means that there is a delay problem in the SAR image. It is recommended to adjust the time difference before performing scene matching guidance.

10. The scene matching guidance system based on micro synthetic aperture radar according to claim 9, characterized in that: The scene matching unit is based on a trust index Arrange the target area from high to low, the volatility index Included in volatility threshold When the matching index is given priority High SAR image and credibility index The high target area is image matched for guidance, and based on the matching results, the digital elevation model is used to Synchronous track.

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