A dynamic ship radar one-dimensional range image distance resolution test method

Abstract

The application discloses a kind of dynamic ship radar one-dimensional range image distance resolution test methods, a plurality of reflectors are arranged on target ship along a straight line, and the spacing of reflector is close to distance resolution;More than two high-precision positioning devices with time stamp are arranged at different positions on the ship, and the radar system is configured with time system device capable of synchronizing with the positioning device on the ship;Record the position information of the positioning device with time stamp on target ship, the one-dimensional range image data formed by radar to ship, especially the one-dimensional image image data containing time stamp;According to the effective image data, the positioning data of target ship at corresponding time is extracted by time synchronization method, the angle between the straight line where the reflector is located and the radial direction of radar is calculated, and the length of the projection of the spacing of reflector in the radial direction of radar;The length is the effective value of the one-dimensional range image resolution of radar.The present application has strong operability, and can effectively solve the problem of difficult testing and verification of radar one-dimensional range image imaging effect on dynamic ship.

Description

Technical Field

[0001] This invention belongs to the field of radar testing and verification technology, and in particular relates to a method for testing the range resolution of a one-dimensional range image of a dynamic ship radar. Background Technology

[0002] With the development of modern radar, its functions are further developing towards multi-functionality. More and more maritime radars have broadband imaging capabilities. The experimental verification and testing methods for a key indicator of broadband imaging—range resolution—need to be scientific and highly operable. Because experiments related to sea surface targets are subject to various limitations such as sea conditions and administrative management, and are also very costly, high demands are placed on the scientific rigor and operability of their experimental methods.

[0003] Because the range resolution requirements for one-dimensional range images in radar broadband are very high, often between 50 centimeters and 5 meters, while the range resolution of radar detection channels is often between 50 meters and several hundred meters, the experimental verification methods vary greatly. Currently, there is no specific description in various documents for range resolution testing of one-dimensional range images.

[0004] Current testing methods often involve installing reflectors on a ship, assuming the line connecting the reflectors aligns with the radar's radial direction. The resolution of the radar's broadband one-dimensional range image is determined by measuring the distance between the reflectors and reviewing the number of radar images. Because this method primarily considers the reflector imaging effect and neglects the ratio of the reflector's radius to the required resolution, and given the limited number of reflectors visible from the sea surface, it can only roughly measure the broadband one-dimensional imaging resolution for indicators with relatively high resolution (resolved range). It is difficult to test indicators with higher resolution requirements. Summary of the Invention

[0005] The purpose of this invention is to address the difficulty in testing the imaging effect of one-dimensional radar range images in real-world environments, and to propose a scientific, effective, simple, and feasible method for testing the range resolution of one-dimensional range images of dynamic ship targets.

[0006] To achieve the objective of this invention, a method for testing the range resolution of a one-dimensional range image of a dynamic ship radar is disclosed, specifically including the following steps:

[0007] Step 1: Arrange several reflectors along a straight line on the target vessel. The distances between the reflectors are not exactly the same and are close to or less than the expected range resolution index. Arrange no less than two high-precision positioning devices with timestamps at different positions on the target vessel, one at the bow and one at the stern.

[0008] Step 2: Deploy a timing device in the ground radar system that can synchronize with the high-precision positioning equipment of the target vessel. The timing device is used to synchronize the positioning data of the reflector attitude on the target vessel with the radar test data.

[0009] Step 3: Based on the one-dimensional range image data of the ship formed by the radar, process the data to form one-dimensional image data with timestamps; determine whether the number and distribution of peaks in the one-dimensional image data conform to the pattern of the deployed reflectors, and determine the specific reflectors deployed on the ship corresponding to the peaks of the one-dimensional image.

[0010] Step 4: When the number and distribution of spikes in the one-dimensional image data conform to the pattern of the deployed reflectors, extract the position data of the positioning equipment on the ship at the corresponding time based on the one-dimensional image data containing timestamps, calculate the angle between the straight line where the reflector is located and the radial direction of the radar, and thus obtain the length of the projection of the reflector spacing in the radial direction of the radar; obtain the effective value of the range resolution of the radar one-dimensional range image based on this length.

[0011] Furthermore, the test is a dynamic test based on the target ship's navigation state. During the test, the target ship is in a navigation state at sea state no higher than level four. The target is a fiberglass ship or a wooden ship. During the test, the ship is at least 500 times the length of the ship from the radar, and the ship's navigation direction forms an angle of 10° to 20° with the radar's radial direction.

[0012] Furthermore, in step 1, the diameter of the reflector cannot exceed 1 / 4 of the expected resolution index; the center-to-center spacing of the reflectors should be close to the expected resolution index, with a recommended value between 0.9 and 1.1 times the expected resolution index; the number of reflectors should be no less than 4, and the reflector placement should avoid metal parts on the ship; the positioning equipment error should be less than 0.5 meters.

[0013] Furthermore, in step 2, since the target vessel's attitude is dynamically changing, the test data is synchronized with the target attitude by synchronizing the timestamps of the timing equipment on the vessel and the radar system's own timing equipment. The data rate of the timing equipment is not less than 10Hz, and the time synchronization accuracy is not greater than 40 milliseconds.

[0014] Furthermore, in step 3, the data processing involves pulse compression, accumulation, and optimal filtering of the effective broadband pulse data of the one-dimensional distance image data.

[0015] Furthermore, in step 3, the one-dimensional image data has multiple peaks, with each reflector corresponding to one peak. The measured distance between the peaks is the measured projection distance of the reflector in the radial direction of the radar. Since the distances between reflectors are not exactly the same when they are arranged, based on the measured projection distance and the known spacing between the reflectors during arrangement, it is possible to determine whether the number and distribution of peaks conform to the pattern of the deployed reflectors, and to determine the specific reflector arranged on the ship corresponding to the peak of the one-dimensional image.

[0016] Further, in step 4, the positioning data of the positioning device on the ship at the corresponding time is extracted synchronously based on the one-dimensional image data and the timestamp. Based on the positioning data, the angle between the reflector placed on the ship and the radar radial direction at the imaging time can be calculated. Based on the angle value and the distance between the reflectors, the projected distance of the distance between the reflectors in the radar radial direction at the imaging time is calculated. The minimum value of this projected distance is the effective value of the range resolution of the radar for broadband one-dimensional range imaging of moving targets on the sea surface.

[0017] Furthermore, based on the timestamps corresponding to the effective imaging data, the positioning data of the target vessel at the corresponding time is extracted synchronously using the timestamps; using the coordinates of the target vessel's positioning equipment and the ground radar system, the real-time heading of the vessel and the angle θ between the target vessel's heading and the radar radial direction are calculated, and the range resolution R is calculated according to the following formula. 成像 :

[0018] R 成像 =cosθ*R

[0019] Where R is the center-to-center distance between the reflectors.

[0020] Compared with the prior art, the significant advancements of this invention are: 1) This test method can not only directly measure the range resolution of the radar for a one-dimensional range image of a moving vessel target; but also has a high success rate and good operability; 2) In response to the problem that the imaging effect of the radar for a one-dimensional range image of a moving vessel target is difficult to quantify and test in a real environment, this invention provides a test method that is highly implementable and can scientifically measure the imaging results, which can effectively solve the problem of difficulty in testing and verifying the imaging effect of the radar for a one-dimensional range image of a dynamic vessel.

[0021] To more clearly illustrate the functional characteristics and structural parameters of the present invention, further explanation is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the imaging distance resolution test scenario;

[0024] Figure 2 This is a schematic diagram of the reflector arrangement on the ship;

[0025] Figure 3 This is a schematic diagram of the imaging effect;

[0026] Figure 4 This is a schematic diagram of the imaging resolution distance calculation. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] A method for testing the range resolution of a one-dimensional range image of a dynamic ship radar, specifically including the following steps:

[0029] Step 1: Arrange several reflectors along a straight line on the target vessel. The distances between the reflectors are not exactly the same and are close to or less than the expected range resolution index. Arrange no less than two high-precision positioning devices with timestamps at different positions on the target vessel, one at the bow and one at the stern.

[0030] Step 2: Configure a synchronization device between the ground radar system and the high-precision positioning equipment of the target vessel. The synchronization device is used to synchronize the attitude data of the reflector on the target vessel and the radar test data.

[0031] Step 3: Based on the one-dimensional range image data of the ship formed by the radar, process the data to form one-dimensional image data with timestamps; determine whether the number and distribution of peaks in the one-dimensional image data conform to the pattern of the deployed reflectors.

[0032] Step 4: When the number and distribution of spikes in the one-dimensional image data conform to the pattern of the deployed reflectors, extract the position data of the positioning equipment on the ship at the corresponding time based on the one-dimensional image data containing timestamps, calculate the angle between the straight line where the reflector is located and the radial direction of the radar, and thus obtain the length of the projection of the reflector spacing in the radial direction of the radar; obtain the effective value of the range resolution of the radar one-dimensional range image based on this length.

[0033] Specifically, range resolution refers to the range resolution of broadband imaging (one-dimensional range image) mode. The test is a dynamic test based on the ship's navigation state. During the test, the target ship is in a navigation state not exceeding sea state four; the target ship is made of fiberglass or wood, the ship's navigation distance is not less than 500 times its length, and the ship's navigation direction forms an angle of 10° to 20° with the radar's radial direction. The range resolution test result is the projection of the line segment between the centers of the reflectors onto the line connecting the radar and the centers of the reflectors (on the ship). The angle between this line and the line connecting the centers of the radar and the centers of the reflectors (on the ship) is determined using positioning equipment.

[0034] Specifically, the vessel's RCS (radar cross-section) should be as small as possible, with fiberglass or wooden boats being the preferred materials. There should be at least four reflectors, positioned to avoid contact with metal parts on the vessel. The spacing between adjacent reflectors should be close to or less than the range resolution, and all reflectors should be arranged in a straight line for easy testing and verification. The reflector diameter should be less than 1 / 4 of the range resolution; to ensure safe and convenient installation, lighter reflectors with the same capabilities should be selected.

[0035] Specifically, positioning equipment should be strategically placed on the vessel (ideally aligned with the reflector on a straight line, or parallel to the reflector's position, with maximum spacing between devices, ensuring one at the bow and one at the stern). The installation location, accuracy, and time synchronization function of the positioning equipment must meet requirements. At least two positioning devices are required, both aligned with or parallel to the reflector's position. Positioning accuracy must meet requirements, generally less than 0.5 meters, and time synchronization accuracy no greater than 40 milliseconds. A time synchronization device should be added to the radar system, ensuring sufficient accuracy.

[0036] Specifically, the ship travels at a normal speed (generally 8 to 20 knots), and the radar detects it using broadband one-dimensional range imaging, recording relevant data of the effective imaging. Effective imaging data is defined as follows: the number of imaging spikes is no less than half the number of reflectors, and the distance between adjacent reflectors can be measured. The principle of one-dimensional range imaging is as follows: through pulse compression, accumulation, and optimal filtering of the effective broadband pulse data, multiple spikes are generally formed for the target. For the ship target with reflectors in this experiment, spike imaging results corresponding to the reflectors will appear. In the optimal case, each reflector corresponds to one spike. The distance between the spikes measured in the one-dimensional range image result is the projected distance of the reflector in the radial direction of the radar.

[0037] Specifically, based on valid imaging data, including graphics, video, and peak imaging data; distance measurements of each reflector; and data from the ship's positioning equipment, the system first extracts the positioning data of the ship's positioning equipment at the corresponding time by comparing the imaging data with timestamps. Based on this positioning data, the angle between the reflector placed on the ship and the radar's radial direction at the imaging time can be calculated. Then, based on the angle value and the distance between the reflectors, the projected distance of the reflector spacing in the radar's radial direction at the successful imaging time is calculated. The minimum value of this projected distance is the range resolution of the radar for broadband one-dimensional range imaging of moving targets on the sea surface.

[0038] Example

[0039] The technical solution of the present invention will be described in detail below with reference to the formulas and accompanying drawings.

[0040] 1) Test conditions

[0041] a) The radar has a line-of-sight capability over the target vessel's navigation area;

[0042] b) The length of the vessel shall not be less than 6m;

[0043] c) The time synchronization accuracy of the time synchronization equipment shall not exceed 20ms;

[0044] d) The positioning error of the high-precision positioning equipment does not exceed 0.3m;

[0045] e) The sea conditions in the test area meet the requirements for safe navigation.

[0046] 2) Test Procedure

[0047] a) Deploy a vessel with 2-5 metal rods or other reflectors that meet the requirements (the diameter of the reflector used for resolution testing should not exceed 1 / 4 of the predicted resolution index). The spacing between the reflectors should be between 0.9 and 1.1 times the predicted resolution index D (the spacing between reflectors should not be all the same; ideally, the middle 1 or 2 spacings should be different from the others to facilitate confirmation of the reflector position corresponding to the measurement value in the one-dimensional distance image). Arrange them in a straight line along the bow and stern. Figure 2 As shown. Small vessels conducted tests within a range of 0.3 to 0.7 times the maximum radar imaging range L. For example... Figure 1 As shown.

[0048] b) Two high-precision positioning devices are placed on the test vessel along a straight line or parallel line to the location of the reflector, with a distance of not less than 5m between the positioning devices;

[0049] c) The radar equipment is equipped with a high-precision time synchronization device, and the time synchronization error between the time synchronization device and the high-precision positioning device on the ship does not exceed 20ms;

[0050] d) The radar equipment is activated to search for and image cooperative targets on the sea surface. Simultaneously, the cooperative targets on the sea surface begin to move back and forth at a predetermined speed (10-20 knots) along a set route (forming an angle of 10° to 20° along the radar's radial direction) at no less than once, with the radar imaging occurring at least three times during each forward and backward movement. The test area and test route are as follows: Figure 1 As shown.

[0051] e) Record the minimum distance interval for each imaging session based on the imaging images. The minimum distance interval for 6 imaging sessions is the distance resolution of the imaging mode. Fill the results into Table 1.

[0052] f) The vessel carries high-precision positioning equipment to store its time and location information. The radar equipment stores the vessel's tracking data (with time stamps), imaging data (with time stamps), and imaging images or videos in real time. Imaging images are as follows... Figure 3 As shown.

[0053] 3) Data processing methods

[0054] a) By synchronizing with timestamps, extract the positioning data of the positioning device on the target vessel corresponding to the valid imaging data.

[0055] b) Calculate the angle between the ship's real-time heading and the target heading and the radar radial direction based on the two positioning devices. This angle is the angle between the projection of the reflector on the horizontal plane and the radar radial direction.

[0056] c) When the number and distribution of wave crests in a one-dimensional range image obtained by radar conform to the pattern of the deployed reflectors, the range resolution is calculated according to the following formula. (See schematic diagram below.) Figure 4 As shown.

[0057] R 成像 =cosθ*R

[0058] Where θ is the angle between the direction of the line connecting the reflectors and the radial direction of the target ship; R is the distance between the centers of the reflectors.

[0059] Specifically, in this embodiment, the test results are shown in the table below:

[0060] Table 1. Radar Range Resolution Test Record

[0061] Date: Location:

[0062]

[0063] The minimum value among multiple distance resolutions is recorded as the final result.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for testing the range resolution of a one-dimensional range image of a dynamic ship radar, characterized in that, Specifically, the following steps are included: Step 1: Arrange several reflectors along a straight line on the target vessel. The distances between the reflectors are not exactly the same and are close to or less than the expected range resolution index. Arrange no less than two high-precision positioning devices with timestamps at different positions on the target vessel, one at the bow and one at the stern. Step 2: Configure a time synchronization device in the ground radar system that can synchronize with the high-precision positioning equipment of the target vessel. The time synchronization device is used to synchronize the positioning data of the reflector attitude on the target vessel and the radar test data. Step 3: Based on the one-dimensional range image data of the ship formed by the radar, process the data to form one-dimensional image data with timestamps; determine whether the number and distribution of peaks in the one-dimensional image data conform to the pattern of the deployed reflectors, and determine the specific reflectors deployed on the ship corresponding to the peaks of the one-dimensional image. Step 4: When the number and distribution of spikes in the one-dimensional image data conform to the pattern of the deployed reflectors, extract the position data of the positioning equipment on the ship at the corresponding time based on the one-dimensional image data containing timestamps, calculate the angle between the straight line where the reflector is located and the radial direction of the radar, and thus obtain the length of the projection of the reflector spacing in the radial direction of the radar; obtain the effective value of the range resolution of the radar one-dimensional range image based on this length. In step 4, the positioning data of the ship's positioning device at the corresponding time is extracted synchronously based on the one-dimensional image data and the timestamp. Based on the positioning data, the angle between the reflector placed on the ship and the radar radial direction at the imaging time can be calculated. Based on the angle value and the distance between the reflectors, the projected distance of the distance between the reflectors in the radar radial direction at the imaging time is calculated. The minimum value of this projected distance is the effective value of the range resolution of the radar for broadband one-dimensional range imaging of moving targets on the sea surface. By synchronizing with timestamps, the effective imaging time is extracted, along with the positioning data corresponding to the positioning equipment deployed on the target vessel. Using the coordinates of the target vessel's positioning equipment and the ground radar system, the real-time heading of the vessel at the effective imaging time and the angle between the target vessel's heading and the radar's radial direction are calculated. And calculate the range resolution according to the following formula. : Where R is the center-to-center distance of the reflectors; the minimum value among multiple distance resolutions is recorded as the final result.

2. The method for testing the range resolution of a one-dimensional range image of a dynamic ship radar according to claim 1, characterized in that, The test is a dynamic test based on the target vessel's navigation state. During the test, the target vessel is in a navigation state at sea state no higher than level four. The target vessel is made of fiberglass or wood, and the distance between the vessel's navigation area and the radar is no less than 500 times the length of the vessel. The vessel's navigation direction forms an angle of 10° to 20° with the radial direction of the radar.

3. The method for testing the range resolution of a one-dimensional range image of a dynamic ship radar according to claim 1, characterized in that, In step 1, the diameter of the reflector cannot exceed 1 / 4 of the expected distance resolution index; the number of reflectors is not less than 4, and the reflector positions avoid metal parts on the ship; the positioning device error is less than 0.5 meters.

4. The method for testing the range resolution of a one-dimensional range image of a dynamic ship radar according to claim 1, characterized in that, In step 2, since the target ship's attitude is changing dynamically, the test data is synchronized with the target attitude by synchronizing the timestamps of the ship's timing equipment and the radar system's own timing equipment. The data rate of the timing equipment is not less than 10Hz and the time synchronization accuracy is not greater than 40 milliseconds.

5. The method for testing the range resolution of a one-dimensional range image of a dynamic ship radar according to claim 1, characterized in that, In step 3, the data processing procedure involves pulse compression, accumulation, and optimal filtering of the effective broadband pulse data of the one-dimensional range image data.

6. The method for testing the range resolution of a one-dimensional range image of a dynamic ship radar according to claim 1, characterized in that, In step 3, the one-dimensional image data has multiple peaks, with each reflector corresponding to one peak. The measured distance between the peaks is the projected distance measurement of the reflector in the radial direction of the radar. Since the distances between reflectors are not exactly the same when they are arranged, based on the projected distance measurement and the known distance between the reflectors during the arrangement, it is possible to determine whether the number and distribution of peaks conform to the pattern of the arranged reflectors and to identify the reflector corresponding to the peak.

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