A detection method for multifunctional spaceborne wide-area imaging search radar

Abstract

The invention relates to a multifunctional satellite-borne wide-area imaging search radar detection method, comprising the following steps: 1) search and detection task planning: carrying out task planning for an area to be searched and detected according to relevant parameters of a satellite-borne radar system, and calculating a wide-area rapid search working mode; 2) carrying out a wide-area rapid search working mode for an area along a track, and obtaining an imaging result of the area through on-orbit real-time imaging processing, thereby detecting, screening and locating a target of interest; 3) calculating and selecting a reasonable high-resolution beamforming working mode for parameters of the target of interest output by the wide-area rapid search mode, including range, azimuth resolution, and range azimuth width; 4) carrying out a target recognition and confirmation task workflow, and imaging the targets of interest in the area one by one with high resolution; 5) outputting a target recognition and confirmation result; and 6) looping through steps 1)-5) to carry out observation of the next area along the track.

Description

Technical Field

[0001] The invention mainly relates to the field of satellite-borne radar sea detection imaging, and specifically proposes a new multifunctional satellite-borne wide-area imaging search radar detection method. Background Art

[0002] The current observation working mode of spaceborne radar is relatively simple, that is, each time it flies over a designated area, it can only work in a certain fixed mode. For example, the circular scanning radar based on the microwave scatterometer working system (Research on Spaceborne Fan-beam Scanning Microwave Scatterometer System Lin Wenming; Research on Airborne Surround SAR Sea Surface Characteristics and Ship Target Detection Algorithm_Pan Xueli) can only realize continuous search and detection of wide-area sea surface areas, with an image resolution of hundreds of meters. The product information provided can only be some "point targets". Limited by the resolution of the radar work, the radar cannot further provide high-resolution image information of the detected target, and needs to be realized through the cooperation of other earth observation spaceborne radar satellites.

[0003] In addition, the working modes of the currently in-orbit synthetic aperture radar (SAR) satellites are generally fixed to imaging modes such as strip, TOPS, and spotlight each time they are turned on. Figure 1 As shown, the TOPS mode can achieve continuous wide-swath imaging at low resolution. The schematic diagram of the working mode is shown below: Currently, the on-orbit spaceborne SAR system does not have a working mode in which multiple modes work together, which to some extent affects the observation efficiency of the spaceborne radar.

[0004] There is no current satellite-borne radar operating mode that can achieve coordinated cooperation of wide-area search and high-resolution spotlight imaging on a single satellite, while also enabling continuous satellite-borne radar operation in the ground coverage area. Summary of the invention

[0005] In response to this technical problem, the present invention proposes a multifunctional satellite-borne wide-area imaging search radar detection method. Through the reasonable setting of the radar satellite system working mode parameters, the method can enable the satellite-borne radar satellite to simultaneously realize wide-area search imaging and target beam high-resolution imaging during a single startup process. At the same time, the continuity of the observation area along the track direction can realize large-area sea surface observation, which greatly improves the earth observation efficiency of the satellite-borne SAR satellite.

[0006] The technical solution of the present invention is: a multifunctional spaceborne wide-area imaging search radar detection method, comprising the following steps:

[0007] 1) Search and detection mission planning: According to the relevant parameters of the onboard radar system, the mission planning is carried out for the area where the search and detection is to be carried out, and the working mode of wide-area rapid search is calculated;

[0008] 2) Carry out wide-area rapid search in the area along the track, and obtain imaging results of the area through on-orbit real-time imaging processing, and then detect, screen and locate the target of interest;

[0009] 3) Calculate and select the high-resolution beamforming mode for the parameters of the target of interest output by the wide-area rapid search mode, including range and azimuth resolution, and range and azimuth width;

[0010] 4) Carry out the target identification and confirmation task workflow, and obtain high-resolution images of the targets of interest in the area one by one;

[0011] 5) Output the identification and confirmation results of the target of interest;

[0012] 6) Loop through steps 1)-5) to conduct observations in the next area along the track, achieving multifunctional integrated work of wide-area rapid search, imaging recognition and confirmation.

[0013] Beneficial effects:

[0014] Different from the traditional wide-area imaging mode of satellite-borne radar, the mode of the present invention is an imaging mode that adopts SAR high resolution in range and low resolution in azimuth. By reducing the resolution in azimuth, the imaging time can be effectively reduced, and a wide-width search imaging in range can be achieved within a specified time. At the same time, the high resolution in range retains the image information in the range of the scene target, which can improve the detection probability and classification probability of the target in the image. Through real-time imaging processing and target positioning on the satellite, the target of interest can be screened and located in the search imaging results, and then the SAR payload system can automatically switch to the current high-resolution spotlight imaging mode to achieve high-resolution imaging of the target of interest.

[0015] It can realize the integrated application of target search, discovery, classification, target imaging, recognition and confirmation, and achieve target discovery and recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of onboard TOPS working mode;

[0017] Figure 2 Schematic diagram of the detection method of the multifunctional wide-area search radar;

[0018] Figure 3 Flow chart of multifunctional wide-area search radar detection method;

[0019] Figure 4 Detailed timing design diagram for Region 1. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all 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 protection scope of the present invention.

[0021] According to an embodiment of the present invention, a multifunctional spaceborne wide-area imaging search radar detection method is proposed, wherein the working mode schematic diagram of the radar is as follows: Figure 2 As shown, for the convenience of analysis, three regions are shown here. The satellite flies along the track direction, and through the reasonable optimization configuration of azimuth time, it alternates between wide-area rapid imaging and target high-resolution beamforming modes. Taking region 1 as an example, rapid wide-area imaging is to carry out rapid imaging of the entire region 1. The imaging process is to quickly image multiple sub-band areas one by one (region 1 is divided into multiple range sub-bands along the range direction). According to the results of wide-area rapid search imaging, target high-resolution beamforming imaging is carried out, as shown in the point target diagram in region 1. After completing wide-area rapid imaging and target high-resolution beamforming in region 1, the satellite carries out the same workflow for regions 2 and 3 in turn along the azimuth time. The detailed workflow diagram for each region is shown in the figure below. Figure 3 shown.

[0022] like Figure 3 As shown, a multifunctional spaceborne wide-area imaging search radar detection method comprises the following steps:

[0023] 1) Search and detection mission planning: Based on the relevant parameters of the satellite-borne radar system (orbital height H, antenna azimuth length L a , antenna distance to height L r 、Azimuth scanning capabilityθ scan ) Carry out mission planning for the area to be searched and detected, and calculate the working mode of wide-area rapid search (mainly the distance ρ r , azimuth resolution ρ a , distance-azimuth width); in traditional design, in order to achieve continuous observation in azimuth, the azimuth resolution of spaceborne SAR is generally designed to be k a >1 is the system widening factor, N is the number of range sub-bands, and the range width of each sub-band is W r Determined by the actual performance of the SAR system, the azimuth width W a Determined by the azimuth scanning capability, but under this design method, the imaging time of area 1 is about W a / V st , where V st Due to the satellite speed, after completing the imaging, the satellite just moves to area 2, and the system does not have additional time to carry out the high-resolution beamforming working mode.

[0024] By adopting the system design of the present invention, the azimuth resolution can be designed to be is a natural number. In this case, the imaging time of area 1 is about After completing wide-area rapid imaging, there is still a certain amount of time left to carry out the high-resolution beamforming working mode. In this way, wide-area rapid imaging and target high-resolution beamforming imaging modes can be achieved simultaneously during the observation of each area, and the satellite can be continuous along the track direction.

[0025] 2) Carry out wide-area rapid search mode, and obtain regional imaging results through on-orbit real-time imaging processing, and then detect, screen and locate targets of interest.

[0026] 3) For the parameters of the target of interest output by the wide-area rapid search mode, calculate and select a reasonable high-resolution beamforming working mode, mainly the range and azimuth resolution, and the range and azimuth width); from step 1, it can be obtained that the system can carry out the working time of high-resolution beamforming recognition of the target is The range and azimuth resolution can be selected based on the number of targets that need to be identified with high resolution, and the selection range is 2m to 5m. The range and azimuth width of the beamforming mode is determined by the azimuth and range antenna lengths of the system.

[0027] 4) Carry out the target identification and confirmation task workflow, and perform high-resolution imaging of the targets of interest in the area one by one.

[0028] 5) Output the target identification confirmation results of interest.

[0029] 6) Repeat steps 1)-5) to carry out observation of the next area along the track, thus realizing the multifunctional integrated work of wide-area rapid search, imaging recognition and confirmation.

[0030] An embodiment of the method based on an actual satellite-borne radar system is given below:

[0031] Orbital altitude: 500km;

[0032] Antenna size: 4.8m (azimuth) × 1.2m (range);

[0033] Antenna scanning capability: ±25° in range; ±15° in azimuth;

[0034] System band: Ku band;

[0035] According to the existing satellite radar mode design method, in order to achieve continuous imaging in the track direction, the system can achieve the following two main working modes:

[0036] Strip: 3m / 30km

[0037] TOPS: 80m (azimuth) × 80m (distance) / 60km (azimuth) × 700km (distance)

[0038] Both working modes can continuously image along the track direction, but there is no extra time to complete high-resolution target identification and confirmation.

[0039] By adopting the method of the present invention, the imaging accumulation time can be effectively reduced by reducing the azimuth resolution, while improving the range resolution and increasing the probability of target detection. The following working mode is designed:

[0040] Wide-area search detection: 2m (distance) × 100m (azimuth) / 60km (azimuth) × 700km (distance), corresponding to an area in the figure (area 1)

[0041] High-resolution beamforming mode: 5m×5m / 5km×5km

[0042] In this way, continuous imaging in azimuth can be achieved, and then Figure 2 The workflow shown can realize the multifunctional integrated work of wide-area rapid search, imaging recognition and confirmation. Figure 4 Detailed time allocation for Region 1 is given.

[0043] Although the above describes the illustrative specific embodiments of the present invention to facilitate those skilled in the art to understand the present invention, and it should be clear that the present invention is not limited to the scope of the specific embodiments, for those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

Claims

1. A multifunctional spaceborne wide-area imaging search radar detection method, characterized in that: The steps include: 1) Search and detection mission planning: According to the relevant parameters of the onboard radar system, the mission planning is carried out for the area where the search and detection is to be carried out, and the working mode of wide-area rapid search is calculated; 2) Carry out wide-area rapid search in the area along the track, and obtain imaging results of the area through on-orbit real-time imaging processing, and then detect, screen and locate the target of interest; 3) Calculate and select the high-resolution beamforming mode for the parameters of the target of interest output by the wide-area rapid search mode, including range and azimuth resolution, and range and azimuth width; 4) Carry out the target identification and confirmation task workflow, and obtain high-resolution images of the targets of interest in the area one by one; 5) Output the identification and confirmation results of the target of interest; 6) Execute steps 1)-5) repeatedly to carry out observations in the next area along the track, achieving wide-area rapid search, imaging recognition and confirmation multifunctional integration; The relevant parameters of the satellite-borne radar system include: orbit height H, antenna azimuth length L a , antenna distance to height L r 、Maximum scanning angle θ in antenna azimuth scan ; The parameters of wide area fast search and high resolution beamforming working modes include the distance ρ r , azimuth resolution ρ a , distance-azimuth width; In step 1), the azimuth resolution is designed to be , n >1, the larger n is, the lower the azimuth resolution of the system is, k a >1 is the system azimuth resolution broadening factor, N is the number of range sub-bands, and the range width of each sub-band is W r Determined by the actual performance of the SAR system, the azimuth width W a It is determined by the maximum scanning angle of the SAR system antenna in azimuth. In this case, the imaging time of the area is , where V st The satellite speed is 100 times that of the satellite. After completing wide-area rapid imaging, the high-resolution spotlight working mode is carried out in the remaining time. In the observation process of each area, wide-area rapid imaging and target high-resolution spotlight imaging modes are realized simultaneously, and the satellite is continuous along the track direction. In step 3), the working time of the system for carrying out high-resolution beam recognition of the target is obtained from step 1: , where V st is the satellite speed, and the range and azimuth resolution is selected according to the number of targets that need to be identified with high resolution, with the selection interval being 2m~5m; the range and azimuth width of the beamforming mode is determined by the azimuth and range antenna lengths of the system.

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