A False Target Analysis Method Based on Air Traffic Control Secondary Radar

Abstract

This invention provides a false target analysis method based on air traffic control secondary radar, comprising: for target traces located in non-reflection zones, if the traces are not related to existing real tracks, determining whether the target traces are related to a reflection track file; if they are related, the trace is a false target trace, the false target track information is updated, and the process ends; otherwise, for target traces located in reflection zones, performing a region test on the traces, determining whether the trace is a real target trace and the total weight of the test items based on the test results; performing sub-test items on the traces, and updating the total weight of the test items based on the test results; comparing the total weight with a total weight threshold, and determining the authenticity of the target report based on the comparison result. This invention also provides a corresponding system. The method of this invention solves the technical problem that existing air traffic control secondary radar systems can only simply discard false targets.

Description

Technical Field

[0001] This invention relates to the field of secondary radar monitoring for civil air traffic control, and specifically to a method and system for analyzing false targets based on secondary air traffic control radar, developed using the Windows development platform. Background Technology

[0002] The secondary radar system for air traffic control is a fundamental piece of equipment in the air traffic control system. It features air traffic control interrogation capabilities, can operate continuously without downtime, and can be unattended. It can acquire information such as distance, bearing, speed, flight code, altitude code, identification code, and special codes of cooperative aerial targets in real time, around the clock and in all weather conditions. It possesses high detection accuracy and anti-jamming capabilities, and can monitor the flight status of cooperative targets in real time, providing air traffic control departments with real-time route (line) surveillance and real-time airspace surveillance information for key areas.

[0003] To ensure safe and reliable aircraft flight, the analysis of false targets caused by asynchronous interference, reflection, circling, and splitting in air traffic control secondary radar becomes crucial. Traditional secondary radar systems can only simply filter and discard false targets, and since no alarms or incidents occur, there is no subsequent investment of manpower and time in the statistical analysis of the false targets that appear. Furthermore, since there are currently no relevant algorithms and software available in China, we are also unable to perform real-time analysis of false targets appearing in air traffic control secondary radar. Summary of the Invention

[0004] The present invention aims to provide a false target analysis method based on air traffic control secondary radar, so as to solve the technical problem that the original air traffic control secondary radar system can only simply discard false targets.

[0005] To achieve the above objectives, the present invention provides a false target analysis method based on air traffic control secondary radar, comprising:

[0006] S1: For the target's trace in the non-reflection zone, determine whether the target's trace is related to the existing real track. If the trace is not related to the existing real track, determine whether the target's trace is related to the previously established reflection track file. If it is related, the trace is a false target trace. Update the false target track information and then end the false target detection process. Otherwise, proceed to step S2.

[0007] S2: For the traces of the target in the reflection zone, perform a region test on the traces. The region test includes secondary code test, height test, distance test and orientation test. Based on the test results, determine whether the trace is a trace of a real target or whether the trace may be a trace of a false target and determine the total weight of the test items for the false target test.

[0008] S3: Perform five sub-test items: signal amplitude test of the target trace, historical track test, target symmetry test, orbit test and potential reflection test, and update the total weight of the test items of the false target test based on the test results of the five sub-test items;

[0009] S4: Compare the total weight of the test items of the final false target test with the upper and lower limits of the total weight threshold. If the total weight is lower than the lower limit of the total weight threshold, the target is reported as false; if the total weight is higher than the upper limit of the total weight threshold, the target is reported as true; if the total weight is between the upper and lower limits of the total weight threshold, the target is reported as uncertain.

[0010] In step S1, after updating the false target track information, the method further includes: determining whether the false target mark is a mark of a reflective target caused by reflection. If the false target mark is determined to be a mark of a reflective target caused by reflection, the position of the updated reflective surface is obtained based on the detection positions of the real target and the reflective target. The position is compared with the prior stored reflective surface image to form a temporary reflective surface. The temporary reflective surface is superimposed on the stored reflective surface. The reflection area is determined based on the superposition result. Then the false target detection process ends. Otherwise, the false target detection process ends directly.

[0011] Step S2 includes:

[0012] S21: Receive a dot;

[0013] S22: Select an unselected track from the existing real tracks, and perform secondary code testing, altitude testing, distance testing, and bearing testing of the track relative to the track to realize the false judgment processing of the track and the track in step S21.

[0014] Step S22 includes:

[0015] S221: Determine whether the point is successfully related to the secondary code, distance, bearing and altitude of the track, so as to perform secondary code test, altitude test, distance test and bearing test of the point relative to the track;

[0016] S222: If all correlations fail based on the relevant results, it is determined that the point cannot be the point of the false target corresponding to the track, and step S23 is executed; otherwise, it is determined that the point may be the point of the false target corresponding to the track, and the total weight of the test items of the false target test is determined based on the relevant results.

[0017] S23: Determine whether all existing real tracks have been selected in step S22. If so, continue to execute step S3 or end the false target detection process based on the relevant results. Otherwise, return to step S22.

[0018] When continuing to execute step S3 or ending the false target detection process based on the relevant results, if all tracks fail to correlate, the point is a real point, and the false target detection process ends; if there is a successfully correlated track for the point, step S3 is executed directly for the successfully correlated point and track; if there are multiple successfully correlated tracks for the point, the track with the optimal total weight is selected as the final successfully correlated track based on the total weight of the test items in the false target test, and then step S3 is executed.

[0019] The test items for the area test include secondary code testing, height testing, distance testing, and orientation testing; in step S222, the total weight of the test items for the false target test = the sum of the weights of all test items in the area test - the sum of the weights of the test items related to the area test.

[0020] In step S3, the signal amplitude test includes: comparing the signal amplitude of the spot with the signal amplitude of the historical true track; if the signal amplitude of the spot is lower than the signal amplitude of the historical true track, the weight corresponding to the signal amplitude test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the signal amplitude test is increased when updating the total weight of the test items of the false target test.

[0021] The signal amplitude test also includes: setting a minimum difference threshold when the radar is in a special amplitude zone; if the signal amplitude of the spot is higher than the sum of the signal amplitude of the historical track and the minimum difference threshold, then the weight corresponding to the special amplitude zone is added when updating the total weight of the test items of the false target test; otherwise, the total weight of the test items of the false target test remains unchanged.

[0022] In step S3, the historical track test includes: if a new track is established for the point, and there is an earlier established real track with the same secondary code, then the weight corresponding to the historical track test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the historical track test is increased when updating the total weight of the test items of the false target test. The target symmetry test includes: determining whether all responses reported by the target come from the same side of the aiming axis; if so, then the weight corresponding to the target symmetry test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the target symmetry test is increased when updating the total weight of the test items of the false target test.

[0023] The loop test includes: if there exists an existing real track that simultaneously satisfies the following conditions: 1) the target and the existing real track are very close in distance; 2) the target and the existing real track have good code consistency; 3) the signal amplitude of the target is 5-10 dB lower than the signal amplitude of the existing real track, then the weight corresponding to the loop test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the loop test is increased when updating the total weight of the test items of the false target test.

[0024] The potential reflection test includes: if the target's orientation is on the reflective surface, the target is judged as a potential reflection target, and the weight corresponding to the potential reflection test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the potential reflection test is increased when updating the total weight of the test items of the false target test.

[0025] If the target report in step S4 is false, then step S5 is also included: to further distinguish different types of false targets by generating the required maximum distance threshold, minimum distance threshold, maximum azimuth threshold, and minimum azimuth threshold for different false target types;

[0026] If the false target is a reflective target, the position of the updated reflective surface is obtained based on the detection positions of the real target and the reflective target. The position is then compared with the prior stored reflective surface image to form a temporary reflective surface. The temporary reflective surface is then superimposed on the stored reflective surface, and the reflective area is determined based on the superposition result. The false target detection process then ends.

[0027] On the other hand, the present invention provides a false target analysis system based on air traffic control secondary radar, including a communication management module, a data recording module, a track management module, and a data analysis module. The communication management module is configured to receive real-time target data from the air traffic control secondary radar, parse and encapsulate the real-time target data, and then distribute the parsed and encapsulated real-time target data to the data recording module and the track management module. The data recording module is configured to record the real-time target data and save it in a data recording file to obtain historical target data. The track management module is configured to receive point data from the real-time target data and point data from the historical target data, perform track processing on the point data to form target track data. The data analysis module is connected to the track management module and is configured to execute the false target analysis method based on air traffic control secondary radar as described above on the target point data and track data.

[0028] The false target analysis system based on air traffic control secondary radar further includes a target display module and a data playback module. The data playback module is configured to read and manage historical target data from data recording files and / or air traffic control secondary radar data files stored in the data recording module, and provides users with file selection, playback speed setting, and target filtering operations. The target display module is connected to the communication management module and the data playback module, and is configured to display targets detected by the secondary radar based on real-time target data and historical target data. The communication management module receives the real-time target data detected by the air traffic control secondary radar and generates European standard messages.

[0029] The false target analysis method based on air traffic control secondary radar of the present invention can effectively solve the defects of traditional algorithms. At the same time, the algorithm of the present invention is also a major attempt and application of real-time analysis of civil air traffic control secondary radar data quality on false targets.

[0030] The false target analysis method based on secondary air traffic control radar of the present invention can not only statistically analyze false targets, but also provide more detailed data on each test item of false targets. It integrates statistics and analysis, which makes it easier for maintenance technicians to locate equipment problems in a timely manner and take corresponding solutions, greatly improving the work efficiency of maintenance technicians. Attached Figure Description

[0031] Figure 1 This is an installation environment diagram of the false target analysis system based on air traffic control secondary radar of the present invention.

[0032] Figure 2 This is a block diagram of the false target analysis system based on air traffic control secondary radar of the present invention.

[0033] Figure 3 This is a flowchart of the false target analysis method based on air traffic control secondary radar of the present invention.

[0034] Figure 4 This is a schematic diagram showing the position of the reflecting object.

[0035] Figure 5 This is a schematic diagram of a radar operating in a specific amplitude range. Detailed Implementation

[0036] Due to the operating environment and its own design, secondary air traffic control radar may encounter various false targets during actual use. Based on the different causes, these can be mainly categorized as follows: asynchronous, reflection, orbiting, and splitting.

[0037] The false target analysis method based on secondary air traffic control radar of the present invention performs various judgment processes (i.e., false target detection processing) based on the information of the detected target to determine whether it includes common false targets such as reflective targets, surrounding targets, asynchronous targets, split targets, etc. The information of the detected target includes the code of the point and track, altitude, range, signal strength, historical track, potential reflections, etc. Furthermore, the present invention can also, for example, calculate the positions of reflective objects around the radar based on the positions of reflective targets and real targets.

[0038] like Figure 1 The diagram shows the installation environment of the false target analysis system based on air traffic control secondary radar of the present invention. The false target analysis system based on air traffic control secondary radar is installed on a hardware system, such as a user terminal, to perform functions such as data management, data recording, and false target detection. The hardware system meets the following requirements:

[0039] 1) Two serial port servers 400 are provided for each user terminal 300. These two serial port servers 400 are the primary serial port server 401 and the backup serial port server 402.

[0040] 2) Each serial server 400 provides 8 serial ports, configured as RS232 interfaces; each serial server 400 provides 2 network interfaces, supporting 10 / 100Mbps speeds. The network interfaces use standard UDP / IP communication.

[0041] 3) The two serial port servers 400 are connected to two 220V AC power supplies respectively, and a dual power supply current sharing design is adopted.

[0042] The serial server 400 provides a serial-to-network function, which can convert the serial data of the secondary radar into data through the RS-232 serial port and transmit it to the user terminal 300 via the UDP / IP protocol network interface.

[0043] like Figure 2 The diagram shows the module composition of the false target analysis system based on air traffic control secondary radar of the present invention.

[0044] like Figure 2 As shown, the false target analysis system based on air traffic control secondary radar is connected to air traffic control secondary radar 100 and air traffic control secondary radar data file 200. It is configured to receive real-time target data from the air traffic control secondary radar 100 at the site, as well as historical target data stored in the air traffic control secondary radar data file 200 at the site.

[0045] In other words, the false target analysis system based on air traffic control secondary radar of the present invention can receive real-time secondary radar detection data sent by the air traffic control secondary radar and then perform analysis and processing; alternatively, it can read the air traffic control secondary radar data file 200 (i.e., the secondary radar data log file) and then perform analysis and processing. In other embodiments, the air traffic control secondary radar data file 200 may be omitted.

[0046] The false target analysis system based on air traffic control secondary radar includes a communication management module 10, a data recording module 20, a track management module 30, a target display module 40, a data playback module 50, and a data analysis module 60, as well as a user interface 70. The historical target data mentioned above includes historical point data and historical track data, which are provided to the data playback module 50, and the historical track data are provided to the track management module 30.

[0047] The communication management module 10 receives real-time target data detected by the air traffic control secondary radar 100 and generates it as European standard messages (CAT001, CAT002, CAT034, CAT048).

[0048] The communication management module 10 is configured to manage the network communication link between the false target analysis system and the air traffic control secondary radar equipment. Specifically, the communication management module 10 is configured to receive real-time target data from the air traffic control secondary radar 100, parse and encapsulate the real-time target data, and then distribute the parsed and encapsulated real-time target data to corresponding business processing modules such as the data recording module 20, the track management module 30, and the target display module 40. The real-time target data includes real-time point traces and track data. The parsed real-time target data includes altitude, secondary code, distance, bearing, etc. The parsed real-time target data is encapsulated into internal format data, then cached for subsequent operations.

[0049] The data recording module 20 is configured to record the real-time target data and save it in binary format in a data recording file to obtain historical target data. The real-time target data is not modified during recording. It should be noted that the data recording file saved by the data recording module 20 and the air traffic control secondary radar data file 200 mentioned above are both stored on the user terminal in the same location.

[0050] The track management module 30 is configured to receive point data from real-time target data and point data from historical target data, perform track processing on the point data, and form target track data. In this embodiment, the historical target data may come from the data recording file stored in the data recording module 20, or it may come from the air traffic control secondary radar data file 200.

[0051] The data playback module 50 is connected to the data recording module 20 and / or the air traffic control secondary radar data file 200. It is configured to read and manage the historical target data in the data recording file and / or the air traffic control secondary radar data file 200 stored in the data recording module 20. It realizes the playback function of the data recording file and provides users with functions such as file selection, playback speed setting, and target filtering.

[0052] The target display module 40 is connected to the communication management module 10 and the data playback module 50, and is configured to display secondary radar target detection based on real-time target data and historical target data. The target data can be real-time target data received from the network, or historical target data read and managed by the data playback module 50 from the data recording file stored in the data recording module 20 and / or the air traffic control secondary radar data file 200.

[0053] The data analysis module 60 is connected to the track management module 30 and is configured to perform the false target analysis method based on air traffic control secondary radar of the present invention on the target's point data and track data. The target track data can be real-time target track data from the communication management module 10, or historical target track data from the data recording module 20 and / or the data recording file of the air traffic control secondary radar data file 200. Therefore, the data analysis module 60 can receive secondary radar data from the network for real-time data analysis, or it can read the secondary radar data recording file for non-real-time data analysis.

[0054] The user interface 70 is configured to allow for human-computer interaction, logical operations, and to display real-time target data detected by the air traffic control secondary radar 100 and the data analysis results from the data analysis module 60.

[0055] As described above, the false target analysis method based on secondary air traffic control radar of the present invention performs various judgments and processing based on the information of the detected target (i.e., the target's point trace and track data). The information of the detected target includes the code, altitude, distance, signal strength, historical track, potential reflection, etc.

[0056] like Figure 3 As shown, the false target analysis method based on air traffic control secondary radar of the present invention specifically includes the following steps:

[0057] Step S1: For target traces located in the non-reflection zone, determine whether the target trace is related to existing real tracks in historical target track data. If the trace is not related to existing real tracks, perform a correlation test of the reflection trajectory (i.e., A-test). The correlation test of the reflection trajectory refers to determining whether the target trace is related to the previously established reflection track file. If related, the trace is a false target trace, the false target track information is updated, and the false target detection process ends (i.e., the subsequent steps of the method of this invention end); otherwise (i.e., if not related), proceed to step S2.

[0058] The existing real tracks are obtained by querying the track file list. Both reflected track files and real track files are part of the track file list, identified by the fake type.

[0059] Whether a target's point is correlated with an existing real track is mainly determined by the positional relationship between the two. Specifically, a correlation threshold is first set. If the positional interval between the target's point and the existing real track is less than the correlation threshold, the point is successfully correlated with the existing real track; otherwise, the correlation fails.

[0060] Furthermore, to improve the accuracy of determining whether a target's point track is related to an existing real track, this determination also includes a unified check of the target's secondary code, signal amplitude, speed, and heading. Specifically, if the positional interval between the target's point track and the existing real track is less than a relevant threshold, and the point track matches the secondary code, signal amplitude, speed, and heading of the existing real track, then the target's point track is related to the existing real track; otherwise, it is not related.

[0061] The updated false target track information includes the false target's position, secondary code, signal strength, speed, and heading, which is used to complete the false target detection and processing of the track in the future.

[0062] Because of the presence of a reflective surface, the electromagnetic waves from the antenna to the target have two different paths. Therefore, it is possible to determine whether a false target is a reflection target caused by reflection based on the phase difference between the direct path and the reflected path of the target, the change in the width and amplitude of the response pulse after the two signals from the direct path and the reflected path are superimposed, or based on whether a mirage aircraft appears in the secondary radar detection azimuth.

[0063] In step S1, after updating the false target track information, the method further includes: determining whether the false target mark is a mark of a reflective target caused by reflection; if the false target mark is determined to be a mark of a reflective target caused by reflection, then... Figure 4As shown, the updated position of the reflecting surface is obtained based on the detection positions of the real target and the reflecting target. This position is then compared with the previously stored reflecting surface image to form a temporary reflecting surface. This temporary reflecting surface is then superimposed on the stored reflecting surface, and the reflecting area is determined based on the superposition result. The false target detection process then ends. Otherwise, the false target detection process ends directly. Figure 4 In the diagram, R(j) and R(S) represent the distances from the aircraft to the radar and from the reflector to the radar, respectively; β(i) and β(j) represent the direction of the reflector and the azimuth angle of the aircraft's direct path, respectively; dβ is half the angle between the two ends of the reflector and the radar; and β(s) is the orientation angle of the reflector.

[0064] Furthermore, after obtaining the updated reflector position, the process may include sending the updated reflector position to the user interface 70 for display. This allows the user to program the output power on the radar transmitter based on the azimuth angle, thereby reducing the number of reflecting targets caused by reflection interrogation. Moreover, after obtaining the updated reflector position, the process may also include: comparing the updated reflector position with a priori stored reflector map to form a temporary reflector; superimposing the temporary reflector with the stored reflector; and determining the reflection zone based on the superposition result. The area determined based on the temporary reflector is called the temporary reflection zone.

[0065] The prior stored reflective surfaces are obtained based on known geographical information at the radar station site. Temporary reflective surfaces are newly discovered reflective surface information during actual radar use. After existing continuously for a period of time (e.g., 1 day), temporary reflective surfaces will be converted into stored reflective surfaces.

[0066] Step S2: For the traces of the target in the reflection zone, perform a region test (i.e., B test) on the traces. The region test includes secondary code test, height test, distance test and orientation test. Based on the test results, determine whether the trace is a trace of a real target or whether the trace may be a trace of a false target and determine the total weight of the test items for the false target test.

[0067] Area testing (i.e., B-test) determines whether a point might be a false target by examining the correlation between the secondary code, bearing, altitude, and distance of the target corresponding to a point and the secondary code, bearing, altitude, and distance of all existing real tracks in historical target track data. In B-testing, area testing refers to reflection area testing. The specific steps in B-testing are the same as the related processing method in step S1 above for determining whether the target point is correlated with existing real tracks; only the purpose is different. B-testing is used to determine new reflection areas.

[0068] If none of them are relevant, then the point is a real target point, and the false target detection process ends at this point; if there is a correlation, then the point may be a false target point, and when calculating the total weight of the test items for the false target test, the weight corresponding to the relevant test items needs to be subtracted before continuing to execute the "C test".

[0069] Step S2 includes:

[0070] Step S21: Receive a dot pattern, which will be used for subsequent area testing of the dot pattern;

[0071] Step S22: Select an unselected track from the existing real tracks and perform secondary code testing, altitude testing, distance testing, and bearing testing of the point track relative to the track to achieve the false judgment processing of the point track and the track in step S21.

[0072] Step S22 includes:

[0073] Step S221: Determine whether the point is successfully correlated with the secondary code, distance, bearing and altitude of the track, so as to perform secondary code test, altitude test, distance test and bearing test of the point relative to the track;

[0074] Step S222: Based on the correlation results, if all correlations fail, it is determined that the point cannot be the point of the false target corresponding to the track, and step S23 is executed; otherwise, it indicates that at least one of the secondary code, distance, and bearing is correlated, and the point is determined to be the point of the false target corresponding to the track. The total weight of the test items for the false target test is determined based on the correlation results. Therefore, the correlation tests between other tracks and the point can be iterated. After all track correlation tests are completed, the optimal correlation track is selected as the successful correlation track based on the total weight of the test items for the false target test.

[0075] The total weight of the test items in the false target test = the sum of the weights of all test items in the region test (70 in this embodiment) - the sum of the weights of the relevant test items in the region test.

[0076] The area test includes four test items: secondary code test, altitude test, distance test, and orientation test. Each test item corresponds to a weight (the value of which is set according to the actual result). In this embodiment, the sum of the weights of all test items in the area test (i.e., the sum of the weights of the four test items: secondary code test, altitude test, distance test, and orientation test) is 70. The total weight is calculated by subtracting the corresponding weight from the sum of 70 (not by subtracting the corresponding weight from 0) when the result of each test item is relevant. The total weight of the test items in the false target test may be negative.

[0077] Step S23 is used to determine whether all track information related to the point is known.

[0078] Step S23: Traverse the track cache; that is, determine whether all existing real tracks have been selected in step S22. If so, continue to execute step S3 or end the false target detection process according to the relevant results; otherwise, return to step S22.

[0079] When continuing to execute step S3 or ending the false target detection process based on the relevant results, if all tracks fail to correlate, the point is a real point, and the false target detection process ends; if there is a successfully correlated track for the point, step S3 is executed directly for the successfully correlated point and track; if there are multiple successfully correlated tracks for the point, the track with the optimal total weight is selected as the final successfully correlated track based on the total weight of the test items in the false target test, and then step S3 is executed.

[0080] Step S3: Perform five sub-test items (i.e., perform C test) including signal amplitude test, historical track test, target symmetry test, orbit test, and potential reflection test, and update the total weight of the test items of the false target test based on the test results of the five sub-test items.

[0081] ① Signal Amplitude Test

[0082] Signal amplitude testing takes advantage of the fact that the amplitude of a direct signal is generally greater than that of a reflected signal.

[0083] Therefore, the signal amplitude test includes: comparing the signal amplitude of the spot with the signal amplitude of the historical real track, and updating the total weight of the test items of the false target test based on the comparison result.

[0084] Specifically, if the signal amplitude of the target point is lower than the signal amplitude of the historical true track, it may be a false target. When updating the total weight of the test items for the false target test, the weight corresponding to the signal amplitude test is subtracted. Otherwise (i.e., the signal amplitude of the target point matches the signal amplitude of the historical true track), it may be a real target. When updating the total weight of the test items for the false target test, the weight corresponding to the signal amplitude test is added.

[0085] It should be noted that the existing real track is the real track in real time, while the historical real track is the real track in the past. They are the same track, only the track data time is different.

[0086] Special amplitude zone settings: such as Figure 5As shown, when the radar is positioned very low below the reflector, the high elevation cutoff of the antenna causes the amplitude of the reflected signal to be higher than that of the direct signal. Performing signal amplitude tests under these conditions can cause the system to treat false targets as real targets.

[0087] Therefore, the signal amplitude test also includes setting a minimum difference threshold P when the radar is within a specific amplitude range. The ideal value of P is 5 dB (the specific test uses a single value). If the signal amplitude of the target track is higher than the sum of the signal amplitude of the historical track and the minimum difference threshold P, it may be a genuine target. When updating the total weight of the test items in the false target test, the weight corresponding to the specific amplitude range Ws (Ws is set according to the actual situation) is added; otherwise, the weight remains unchanged.

[0088] ② Historical flight track test

[0089] The system considers existing tracks to be more likely to represent real targets than newly established tracks. Therefore, historical track testing needs to assign greater weight to existing tracks.

[0090] The historical track test includes: if a new track is established for the point, and there is an earlier established real track with the same secondary code, then the point is considered to be a false target point, and the weight corresponding to the historical track test is subtracted when updating the total weight of the test items of the false target test; otherwise, it is considered to be a real target, and the weight corresponding to the historical track test is increased when updating the total weight of the test items of the false target test.

[0091] ③ Target symmetry test

[0092] According to the technical principle of monopulse secondary radar, the response signal of the detected target is evenly distributed on both sides of the aiming axis, and the monopulse symbols are negative on the left and positive on the right.

[0093] Target reports generated by reflections do not always have good single-pulse data, and in some cases there is no single-pulse sign change. If all responses to a target report come from the same side of the aiming axis (mainly through the phase detector in the radar receiver outputting "target deviates from the left / right side of the beam aiming axis"), then the system does not assign symmetry weights to it.

[0094] Therefore, the target symmetry test includes: determining whether all responses reported by the target come from the same side of the aiming axis; if so, the dot is considered to be a dot of a false target, and the weight corresponding to the target symmetry test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the target symmetry test is increased when updating the total weight of the test items of the false target test.

[0095] ④ Surround test

[0096] The circling phenomenon has the following characteristics: the circling reports are very close in distance; they have good code consistency; and the amplitude is 5-10 dB lower than the actual target report. (See Table 2 for specific values)

[0097] Therefore, the orbit test includes the following: If there exists an existing real track that simultaneously satisfies the following three conditions: 1) the target and the existing real track are very close in distance; 2) the target and the existing real track have good code consistency; 3) the signal amplitude of the target is 5-10 dB lower than the signal amplitude of the existing real track, then it can be determined to be an orbiting target. In this case, the weight corresponding to the orbit test is subtracted when updating the total weight of the test items of the false target test. Otherwise, it is considered to be a real aircraft, and the weight corresponding to the orbit test is increased when updating the total weight of the test items of the false target test.

[0098] ⑤ Potential reflection test

[0099] Secondary radar can detect the presence of reflective surfaces and create a reflective zone file.

[0100] Therefore, the potential reflection test includes: if the target report originates from the direction of the reflecting surface (the target's azimuth is on the reflecting surface), it is likely a potential reflection. The direct path is received by the sidelobe of the ∑ channel (one channel of the secondary radar receiver), and the reflection path (false target) is received by the main lobe of the ∑ channel. In this case, the target is judged as a potential reflection target, and the weight corresponding to the potential reflection test is subtracted when updating the total weight of the test items for the false target test. Otherwise, it is considered a real aircraft, and the weight corresponding to the potential reflection test is added when updating the total weight of the test items for the false target test.

[0101] The commonly used test items for fake target testing are divided into 6 categories. In this embodiment, the weights of each test item for fake target testing are as follows (which can be modified according to the actual effect):

[0102] Table 1. Weights of test items in the spurious target test.

[0103]

[0104] Step S4: Perform weight evaluation; that is, compare the total weight of the test items of the final false target test with the upper and lower limits of the total weight threshold. If the total weight is lower than the lower limit of the total weight threshold, the target is reported as false; if the total weight is higher than the upper limit of the total weight threshold, the target is reported as true; if the total weight is between the upper and lower limits of the total weight threshold, the target is reported as uncertain.

[0105] In this embodiment, the upper limit of the total weight threshold is 139 and the lower limit is -138. In other embodiments, the total weight threshold can be modified according to the actual effect.

[0106] Therefore, the results of the target report include:

[0107] The actual value is greater than 139

[0108] Uncertain - between 139 and 139

[0109] False value less than -139

[0110] If the target report in step S4 is false, step S5 may also be included: to further distinguish different types of false targets by generating the required maximum distance threshold, minimum distance threshold, maximum azimuth threshold, and minimum azimuth threshold for different false target types.

[0111] In some embodiments, if the type of the false target is determined to be a reflective target, then as follows: Figure 4 As shown, the updated position of the reflecting surface is obtained based on the detection positions of the real target and the reflecting target. This position is then compared with the previously stored reflecting surface image to form a temporary reflecting surface. This temporary reflecting surface is then superimposed on the stored reflecting surface, and the reflecting area is determined based on the superposition result. The false target detection process then ends. Figure 4 In the diagram, R(j) and R(S) represent the distances from the aircraft to the radar and from the reflector to the radar, respectively; β(i) and β(j) represent the direction of the reflector and the azimuth angle of the aircraft's direct path, respectively; dβ is half the angle between the two ends of the reflector and the radar; and β(s) is the orientation angle of the reflector.

[0112] After obtaining the updated reflector position, the process may further include sending the updated reflector position to the user interface 70 for display. This allows the user to program the output power on the radar transmitter based on the azimuth angle, thereby reducing the impact of reflection interrogation on the target. Furthermore, after obtaining the updated reflector position, the process may also include: comparing the updated reflector position with a priori stored reflector map to form a temporary reflector; superimposing the temporary reflector with the stored reflector; and determining the reflection zone based on the superposition result. The area determined based on the temporary reflector is called the temporary reflection zone.

[0113] The specific reference thresholds are shown in Table 2 below.

[0114] Table 2 Distance and orientation thresholds for different types of false targets

[0115]

[0116] Traditional algorithms are too simplistic, only able to crudely discard detected false targets from secondary radar. In contrast, the false target analysis method based on air traffic control secondary radar of this invention can not only statistically analyze false targets, but also provide more detailed data on each test item of false targets. This facilitates maintenance technicians in locating equipment problems in a timely manner and taking corresponding solutions, greatly improving the work efficiency of maintenance technicians.

[0117] Since the results presented by the false target analysis method based on secondary air traffic control radar of this invention mainly depend on the design quality of the developed script program (i.e., the weight values ​​corresponding to the test items), the method of this invention can repeatedly optimize the weight values ​​and threshold values ​​of this algorithm based on actual field test results (modifying the weights of tests B and C and the final threshold values ​​within a certain range according to the actual situation of different radar stations), and can be updated at any time according to subsequent problems and needs, thus enabling high-quality data analysis of false targets from secondary air traffic control radar.

[0118] Traditional algorithms are developed independently by each radar equipment manufacturer and integrated with their own equipment. These differ in data parsing protocols, software functions, and interfaces, making them unusable on equipment from other companies. This invention aims to overcome the limitations of traditional algorithm software by adopting a European standard protocol, providing unified functions and an interface. The same algorithm software can be applied to different types of secondary radar systems, maximizing the utilization of various resources.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made in accordance with the claims and description of this application fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for analyzing false targets based on secondary air traffic control radar, characterized in that, include: Step S1: For the target's trace in the non-reflection zone, determine whether the target's trace is related to the existing real track. If the trace is not related to the existing real track, determine whether the target's trace is related to the previously established reflection track file. If they are related, the trace is a false target trace. Update the false target track information and then end the false target detection process. Otherwise, proceed to step S2. Step S2: For the marks of the target in the reflection zone, perform a region test on the marks. The region test includes secondary code test, height test, distance test and orientation test. Based on the test results, determine whether the dots are real targets or fake targets, and determine the total weight of the test items for the fake target test. Step S3: Perform five sub-test items: signal amplitude test of the spot, historical track test, target symmetry test, orbit test and potential reflection test, and update the total weight of the test items of the false target test based on the test results of the five sub-test items; Step S4: Compare the total weight of the test items in the final false target test with the upper and lower limits of the total weight threshold. If the total weight is lower than the lower limit of the total weight threshold, the target is reported as false. If the total weight value is higher than the upper limit of the total weight value threshold, the objective is reported as true; If the total weight is between the upper and lower limits of the total weight threshold, the target is reported as uncertain.

2. The false target analysis method based on secondary air traffic control radar according to claim 1, characterized in that, In step S1, after updating the false target track information, the method further includes: determining whether the false target mark is a mark of a reflective target caused by reflection. If the false target mark is determined to be a mark of a reflective target caused by reflection, the position of the updated reflective surface is obtained based on the detection positions of the real target and the reflective target. The position is compared with the prior stored reflective surface image to form a temporary reflective surface. The temporary reflective surface is superimposed on the stored reflective surface. The reflection area is determined based on the superposition result. Then the false target detection process ends. Otherwise, the false target detection process ends directly.

3. The false target analysis method based on secondary air traffic control radar according to claim 1, characterized in that, Step S2 includes: Step S21: Receive a dot; Step S22: Select an unselected track from the existing real tracks and perform secondary code testing, altitude testing, distance testing, and bearing testing of the point track relative to the track to achieve the false judgment processing of the point track and the track in step S21. Step S22 includes: Step S221: Determine whether the point is successfully correlated with the secondary code, distance, bearing and altitude of the track, so as to perform secondary code test, altitude test, distance test and bearing test of the point relative to the track; Step S222: Based on the relevant results, if all correlations fail, it is determined that the point cannot be the point of the false target corresponding to the track, and step S23 is executed; otherwise, it is determined that the point may be the point of the false target corresponding to the track, and the total weight of the test items of the false target test is determined based on the relevant results. Step S23: Determine whether all existing real tracks have been selected in step S22. If so, continue to execute step S3 or end the false target detection process based on the relevant results. Otherwise, return to step S22. When continuing to execute step S3 or ending the false target detection process based on the relevant results, if all tracks fail to correlate, the point is a real point, and the false target detection process ends; if there is a successfully correlated track for the point, step S3 is executed directly for the successfully correlated point and track; if there are multiple successfully correlated tracks for the point, the track with the optimal total weight is selected as the final successfully correlated track based on the total weight of the test items in the false target test, and then step S3 is executed.

4. The false target analysis method based on secondary air traffic control radar according to claim 3, characterized in that, The test items for the area test include secondary code testing, height testing, distance testing, and orientation testing; In step S222, the total weight of the test items in the false target test = the sum of the weights of all test items in the area test - the sum of the weights of the test items related to the area test.

5. The false target analysis method based on air traffic control secondary radar according to claim 1, characterized in that, In step S3, the signal amplitude test includes: comparing the signal amplitude of the spot track with the signal amplitude of the historical real track; If the signal amplitude of the dot is lower than the signal amplitude of the historical true track, the weight corresponding to the signal amplitude test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the signal amplitude test is increased when updating the total weight of the test items of the false target test.

6. The false target analysis method based on secondary air traffic control radar according to claim 5, characterized in that, The signal amplitude test also includes: setting a minimum difference threshold when the radar is in a special amplitude zone; if the signal amplitude of the spot is higher than the sum of the signal amplitude of the historical track and the minimum difference threshold, then the weight corresponding to the special amplitude zone is added when updating the total weight of the test items of the false target test; otherwise, the total weight of the test items of the false target test remains unchanged.

7. The false target analysis method based on secondary air traffic control radar according to claim 1, characterized in that, In step S3, the historical track test includes: if a new track is established for the point and there is an earlier established real track with the same secondary code, then the weight corresponding to the historical track test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the historical track test is increased when updating the total weight of the test items of the false target test. The target symmetry test includes: determining whether all responses to the target report come from the same side of the aiming axis; if so, subtracting the weight corresponding to the target symmetry test when updating the total weight of the test items of the false target test; otherwise, increasing the weight corresponding to the target symmetry test when updating the total weight of the test items of the false target test. The orbital test includes: if there exists an existing real track that simultaneously satisfies the following conditions: 1) The target is very close to the existing real flight path in terms of distance; 2) The target has good code consistency with existing real tracks; 3) The target's signal amplitude is 5-10 dB lower than the signal amplitude of existing real tracks. When updating the total weight of the test items of the fake target test, the weight corresponding to the surround test is subtracted; otherwise, when updating the total weight of the test items of the fake target test, the weight corresponding to the surround test is added. The potential reflection test includes: if the target's orientation is on the reflective surface, the target is judged as a potential reflection target, and the weight corresponding to the potential reflection test is subtracted when updating the total weight of the test items of the false target test; otherwise, the weight corresponding to the potential reflection test is increased when updating the total weight of the test items of the false target test.

8. The false target analysis method based on secondary air traffic control radar according to claim 1, characterized in that, If the target report in step S4 is false, then step S5 is also included: to further distinguish different types of false targets by generating the required maximum distance threshold, minimum distance threshold, maximum azimuth threshold, and minimum azimuth threshold for different false target types; If the false target is a reflective target, the position of the updated reflective surface is obtained based on the detection positions of the real target and the reflective target. The position is then compared with the prior stored reflective surface image to form a temporary reflective surface. The temporary reflective surface is then superimposed on the stored reflective surface, and the reflective area is determined based on the superposition result. The false target detection process then ends.

9. A false target analysis system based on air traffic control secondary radar, characterized in that, It includes a communication management module, a data logging module, a trajectory management module, and a data analysis module; The communication management module is configured to receive real-time target data from the air traffic control secondary radar, parse and encapsulate the real-time target data, and then distribute the parsed and encapsulated real-time target data to the data recording module and the track management module. The data recording module is configured to record the real-time target data and save it in a data recording file to obtain historical target data; The trajectory management module is configured to receive point data from real-time target data and point data from historical target data, perform trajectory processing on the point data, and form the target's trajectory data. The data analysis module is connected to the track management module and is configured to perform the false target analysis method based on air traffic control secondary radar as described in any one of claims 1-8 on the target's point data and track data.

10. The false target analysis system based on secondary air traffic control radar according to claim 9, characterized in that, It also includes a target display module and a data playback module; The data playback module is configured to read and manage historical target data from the data recording file and / or air traffic control secondary radar data file stored in the data recording module, and the user can provide file selection, playback speed setting and target filtering operations; The target display module is connected to the communication management module and the data playback module, and is configured to use secondary radar to detect targets based on real-time target data and historical target data. The communication management module receives real-time target data detected by the air traffic control secondary radar and generates it as a European standard message.

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