A method to improve point trace quality based on secondary radar target characteristics

Abstract

The present invention discloses a method for improving the quality of point traces based on secondary radar target characteristics, which includes: judging the validity of the original point traces received by the secondary radar to obtain point trace databases of different modes; traversing the point trace databases of different modes respectively to obtain split point trace data corresponding to each mode; extracting response data from the split point trace data corresponding to each mode to form a split point trace response database; processing the split point trace response database to obtain a point trace database; based on the point trace database and historical point traces, obtaining the corrected point trace database. The present invention can effectively reduce the probability of secondary radar point trace splitting and point trace information errors caused by complex electromagnetic environments.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary radar data processing, and in particular to a method for improving point trace quality based on secondary radar target characteristics. Background Art

[0002] The secondary radar system is one of the current means of monitoring flight targets and controlling airspace safety, and is widely used in civil and military aviation control systems. The secondary radar can provide the location and identity information of flight targets in the monitored airspace, greatly enhancing the aviation command and control of the monitored airspace by military and civil aviation control personnel, and effectively ensuring the safety control of the monitored airspace.

[0003] A variety of surveillance methods are also used to monitor aerial targets, including primary radar, ADS-B and ADS-X. The presence of multiple surveillance devices makes the electromagnetic environment in the air increasingly complex and harsh, resulting in weak response signals during target detection or false targets or erroneous detection information after being affected by strong interference. At present, in a complex electromagnetic environment, it is impossible to effectively identify when the dot trace is split, and it is impossible to effectively correct when the dot trace has information errors. Summary of the invention

[0004] In order to solve the problems of point trace splitting and point trace information abnormality caused by harsh electromagnetic environment, the present invention provides a method for improving point trace quality based on secondary radar target characteristics, which improves the secondary radar point trace quality and greatly improves the target track stability, target information correctness and position accuracy.

[0005] The present invention discloses a method for improving point trace quality based on secondary radar target characteristics, which comprises:

[0006] Step 1: Judge the validity of the original point traces received by the secondary radar to obtain a point trace database of different modes;

[0007] Step 2: traverse the point trace databases of different modes respectively to obtain the split point trace data corresponding to each mode;

[0008] Step 3: extracting response data from the split point trace data corresponding to each mode to form a split point trace response database;

[0009] Step 4: Process the split point trace response database to obtain a point trace database;

[0010] Step 5: Based on the point trace database and the historical point traces, the corrected point trace database is obtained.

[0011] Furthermore, the step 1 comprises:

[0012] If the distance of the original point exceeds the preset distance range, it will be removed;

[0013] If the orientation of the original point trace exceeds the preset orientation range, it will be removed;

[0014] If the response mode of the original point trace is any one of MA, MA / C, MS, M1, and M2, it will be stored in the point trace database of the corresponding mode.

[0015] Furthermore, the point trace database is updated in real time, and is arranged in ascending order according to the distance of the point traces, and is stored in sectors according to the orientation of the point traces.

[0016] Furthermore, the step 2 comprises:

[0017] Step 21: Traverse the points in the point database of different modes:

[0018] If the distance difference between two points in the point database corresponding to the same mode is outside the first preset threshold range, the traversal continues;

[0019] If the distance difference between two point traces in the point trace database corresponding to the same mode is within the first preset threshold range, the azimuth difference of the two point traces will continue to be judged. If the azimuth difference is outside the first preset threshold value, the traversal will continue; wherein the first preset threshold value is 1.5 times the 3dB width of the current transmit beam;

[0020] Step 22: for the traces in the trace database of different modes after traversal, if the trace queues have different modes and are within the mode-related threshold range, mark them as a group of split traces of different answer modes;

[0021] If the points have the same pattern and the same pattern code, they are marked as a group of split points with the same pattern; wherein the pattern code includes MA code, MS code, M1 code, and M2 code.

[0022] Furthermore, the step 3 comprises:

[0023] For the split traces marked as different response modes, extract the first key parameters of each split trace and store them in the split trace response database; wherein the first key parameters include mode information, mode code information, distance and azimuth information, and time information of all response sequences of the trace;

[0024] For the split traces marked as the same mode, the second key parameters of each split trace are extracted and stored in the split trace response database; wherein the second key parameters include the time of all response sequences, the amplitude information of the response code element, the sign bit of the response sequence and its confidence, the distance azimuth information and the sidelobe mark information.

[0025] Furthermore, the step 4 comprises:

[0026] Step 41: performing point fusion on the split point traces belonging to different response modes extracted from the split point trace response database, and storing the fused point traces in the point trace database;

[0027] Step 42: Step 42: Extract several split point traces of the same pattern from the split point trace response database, and judge whether the response information of the split point trace is complete based on the response amplitude and sign bit information in the split point trace response sequence, that is, judge whether it is evenly distributed within the 3dB beam width based on the response amplitude and sign bit information; based on the judgment result, store the corresponding point trace in the point trace database.

[0028] Furthermore, in step 41:

[0029] After fusion, the pattern information of the trace is the pattern fusion of each trace data, the time of the trace is the latest time in all response sequences, the distance information of the trace is the distance of the latest response sequence in the response sequence, and the azimuth information is the average azimuth of each trace.

[0030] Further, the step 42 includes:

[0031] If the response information of the points of the same mode are all complete, the point data with the largest response amplitude value among the points of the same mode are stored in the point database;

[0032] If the response information of the traces of the same mode is incomplete, and the response sequence of each trace is within a 3dB response beam width, it is necessary to fuse the traces and store the fused traces in the trace database; wherein the time of the fused traces is the latest time in all response sequences, the distance information is the distance of the latest response sequence in the response sequence, and the azimuth information is the average azimuth of each trace;

[0033] If the response information of the traces of the same mode are all incomplete, and the response sequence of each trace exceeds a 3dB response beamwidth, the trace with the largest response amplitude value among the traces of the same mode is stored in the trace database;

[0034] If the response information of the dot trace of the same mode contains both complete response sequences and incomplete response sequences, and the dot trace amplitude of the complete response sequence is higher than that of other dot trace information, then other dot trace information is removed, and only the dot trace with the complete response sequence is stored in the dot trace database;

[0035] If the response information of the traces of the same mode contains both complete response sequences and incomplete response sequences, and the trace amplitude of the complete response sequence is smaller than the trace amplitude value of the incomplete response sequence, it is necessary to confirm whether the sidelobe flag of the incomplete response sequence is valid. If the sidelobe flag is valid, it is considered to be a split target, and only the traces of the complete response sequence are stored in the trace database. Otherwise, the traces of the incomplete response sequence are stored in the trace database.

[0036] Furthermore, the step 5 comprises:

[0037] Step 51: Traverse all the traces in the trace database, and compare each trace with all the historical traces corresponding to the first two frames in the historical trace database; if the historical trace is within the preset area of ​​each trace, divide it into the trace queue of the preset area of ​​the trace;

[0038] If there are multiple historical traces in the trace queue of the preset area, continue to screen them: if there are targets with the same pattern and code as the current trace in the historical traces, only the targets with the same pattern and code are retained, otherwise the trace queue of the preset area is deleted;

[0039] Step 52: storing the dot trace data extracted from the dot trace queue of the preset area into the dot trace information correction database; wherein the dot trace data includes dot trace mode, mode code, dot trace orientation, dot trace distance, dot trace height, dot trace amplitude and mark information;

[0040] Step 53: fetching the dot trace data from the dot trace information correction database respectively, and performing code / S mode address judgment according to the corresponding mode to complete error correction of the response information of the dot trace in the dot trace information correction database, thereby obtaining the corrected dot trace database.

[0041] Further, the step 53 comprises:

[0042] If the code / S mode addresses are the same, the altitude is judged. If both the current point trace and the historical point trace have altitude information, the altitude abnormality is judged. If the altitude change threshold is exceeded, the altitude information of the current point trace is corrected to the altitude information of the target in the previous frame.

[0043] If the current trace is an S-mode trace and the historical trace data is not an S-mode trace, no response information error correction will be performed;

[0044] If the dot trace mode is the same and the code is different, the code jump judgment is performed with the code information in the historical data. If the codes of the first two frames of historical data are the same, the code of the current dot trace is corrected to the code of the first two frames; otherwise, the code of the current dot trace remains unchanged.

[0045] Due to the adoption of the above technical solution, the present invention has the following advantages: under the interference of complex electromagnetic environment, the reply code element and reply frame of the secondary radar target will be mutated or lost, which may eventually lead to point trace splitting and point trace information errors. The present invention provides a secondary radar point trace preprocessing method, which analyzes and judges the target characteristics such as the point trace pattern code and reply sequence integrity, combines the historical point trace data to perform regional traversal and comparison, and completes the point trace splitting processing and the correction of erroneous point trace information. The secondary radar point trace quality is improved, and the target track stability, target information correctness and position accuracy are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0047] Figure 1 A functional module block diagram corresponding to a secondary radar point trace preprocessing method according to an embodiment of the present invention;

[0048] Figure 2 The present invention is a flowchart of a secondary radar point trace preprocessing method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present invention.

[0050] See also Figure 1 The embodiment of the present invention provides a functional module block diagram corresponding to a secondary radar point trace preprocessing method, which performs point trace splitting processing and point trace information correction on the original point trace data.

[0051] See also Figure 2 , an embodiment of the present invention provides a data flow diagram of the entire point trace preprocessing of a secondary radar point trace preprocessing method.

[0052] The processing flow of the point splitting part is as follows:

[0053] 1. Original point trace reception

[0054] Receive original point trace data and make validity judgment on the point trace data;

[0055] If the distance in the point data exceeds the set distance range (default 0~500km), it will be discarded;

[0056] If the orientation of the point data exceeds the set orientation range (default 0 to 360°), it will be discarded;

[0057] The target data of the response modes of MA, MA / C, MS, M1 and M2 in the dot trace data are stored in the dot trace library of the corresponding mode;

[0058] The point databases of different modes are updated in real time, and the points are arranged in ascending order of distance and stored in zones according to their distance and azimuth (0 to 360 degrees are evenly divided into 128 small sectors).

[0059] 2. Find the split point trace

[0060] Traverse data in different modes of point trace database;

[0061] If the distance difference between two points is outside the set threshold (75m by default), continue with step 1 for traversal;

[0062] If the distance difference between two points is within the set threshold, the azimuth difference is determined. If the azimuth difference is outside 1.5 times the 3dB width of the current transmit beam, continue with step 1 for traversal.

[0063] For target points whose distance difference and azimuth difference are both within the threshold, the mode is judged. If the modes are different, the mode-related threshold is used for position determination (the distance threshold is 30m, and the azimuth threshold is the 3dB width of the transmitting beam). If it is outside the threshold range, continue with step 1 for traversal.

[0064] If the modes are different and the trace queues are within the mode-related threshold, they are marked as a group of traces with different response modes;

[0065] If the modes are the same and the mode codes (i.e., MA code, MS code, M1 code, M2 code) are the same, they are marked as a group of splitting traces with the same mode;

[0066] Other points are directly stored in the point database.

[0067] 3. Response Data Extraction

[0068] For the points marked with different response modes, the mode information, mode code information, distance and azimuth information of each point and the time information of all the response sequences of the point are extracted and stored in the split point response database;

[0069] For targets marked with the same pattern split traces, the time of all reply sequences of each trace, the reply code element amplitude information, the sign bit of the reply sequence and its confidence, the distance azimuth information and the sidelobe mark information are extracted and stored in the split trace reply database.

[0070] 4. Split point trace processing

[0071] Extract the point trace data of different response modes from the split point trace response database for point trace fusion. The fused point trace mode information is the mode fusion of each point trace data, the point trace time uses the latest time in all response sequences, the point trace distance information uses the distance of the latest response sequence in the response sequence, and the azimuth information uses the average azimuth of each point trace. Store the fused point trace in the point trace database;

[0072] Extract the point trace data of the same mode from the split point trace response database, and determine whether the response information of the split point trace is complete according to the response amplitude and sign bit information in the point trace response sequence, that is, determine whether it is evenly distributed within the 3dB beam width according to the response amplitude and sign bit information;

[0073] If the response information of the group of split point traces is complete, the point trace data with the largest response amplitude value in the group of split point traces is stored in the point trace database;

[0074] If the response information of the group of split traces is incomplete, and the response sequence of each trace is within a 3dB response beam width, the split traces need to be fused. After fusion, the trace time uses the latest time in all response sequences, the trace distance information uses the distance of the latest response sequence in the response sequence, and the azimuth information uses the average azimuth of each trace. The fused traces are stored in the trace database;

[0075] If the response information of the group of split point traces is incomplete, and the response sequence of each point trace exceeds a 3dB response beam width, the point trace data with the largest response amplitude value in the group of split point traces is stored in the point trace database;

[0076] If the response information of the group of split traces contains both complete response sequences and incomplete response sequences, and the trace amplitude of the complete response sequence is higher than that of other trace information, then other trace information is removed, and only the trace with the complete response sequence is stored in the trace database;

[0077] If the response information of this group of split traces contains both complete and incomplete response sequences, and the trace amplitude of the complete response sequence is lower than the trace amplitude value of the incomplete response sequence, it is necessary to confirm whether the sidelobe flag of the incomplete response sequence is valid. If the sidelobe flag is valid, it is considered to be a splitting target, and only the traces of the complete response sequence are stored in the trace database. Otherwise, the traces of the incomplete response sequence are stored in the trace database.

[0078] The processing flow of the point information correction part is as follows:

[0079] 1. Find historical points

[0080] Traverse the point trace database, and compare each point trace with the previous two frames of point trace data in the historical point trace database;

[0081] The position is matched with the current frame trace, and the relevant area is dynamically set according to the target distance. The distance threshold is ±10km, and the azimuth threshold is made according to the current trace distance as shown in Table 1:

[0082] Table 1. Target distance and target related azimuth threshold setting table for current point trace

[0083] Serial number Target distance (lsb:km) Target relative bearing threshold (lsb:°) 1 (0～100] 7.5 2 (100～200] 10 3 (200～300] 15 4 ＞300 20

[0084] If it is in the relevant area, it will be divided into the queue of points in the nearby area of ​​the point;

[0085] After completing the traversal of all historical point trace data, if there are multiple historical point trace data in the point trace queue of the similar area, further screening is required:

[0086] If there are targets with the same pattern and code as the current point trace data in the historical point trace data, only the targets with the same pattern and code will be retained;

[0087] If there is no target with the same mode and code in the historical trace data, the trace queue of the adjacent area will be cancelled, and the current trace will not be processed for subsequent response information error correction.

[0088] 2. Historical Information Extraction

[0089] Extract the dot data in the dot queue of the adjacent area from the dot database, including dot mode, mode code, dot position, dot distance, dot height, dot amplitude and various mark information, and store them in the dot information correction database.

[0090] 3. Response Information Correction

[0091] Extract the dot trace data from the dot trace information correction data, and perform code / S mode address determination according to the corresponding mode;

[0092] If the code / S-mode address is the same, the altitude is judged. If both the current trace and the historical trace have altitude information, the altitude abnormality is judged. If the altitude change threshold (the default is 5000 feet / minute) is exceeded, the altitude information of the current trace is corrected to the altitude information of the target in the previous frame. If the current trace is an S-mode trace and the historical trace data is not an S-mode trace, the response information error correction is not performed.

[0093] If the dot trace mode is the same and the code is different, the code jump judgment is performed with the code information in the historical data. If the codes of the first two frames of historical data are the same, the code of the current dot trace is corrected to the code of the first two frames; otherwise, the code of the current dot trace remains unchanged.

[0094] At this point, the track preprocessing is completed, which can effectively reduce the occurrence of secondary radar track splitting and track information errors caused by complex electromagnetic environment. It provides more real and effective data for processing algorithms such as track correlation, track position smoothing, track code smoothing and track height smoothing in secondary radar track processing.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for improving point trace quality based on secondary radar target characteristics, characterized in that: include: Step 1: Judge the validity of the original point traces received by the secondary radar to obtain a point trace database of different modes; Step 2: traverse the point trace databases of different modes respectively to obtain the split point trace data corresponding to each mode; Step 3: extracting response data from the split point trace data corresponding to each mode to form a split point trace response database; Step 4: Process the split point trace response database to obtain a point trace database; Step 5: Based on the point trace database and the historical point traces, a corrected point trace database is obtained; The step 4 comprises: Step 41: performing point fusion on the split point traces belonging to different response modes extracted from the split point trace response database, and storing the fused point traces in the point trace database; Step 42: extracting a number of split point traces of the same pattern from the split point trace response database, and judging whether the response information of the split point trace is complete according to the response amplitude and sign bit information in the split point trace response sequence, that is, judging whether it is evenly distributed within the 3dB beam width according to the response amplitude and sign bit information; according to the judgment result, storing the corresponding point trace in the point trace database; In step 41: After fusion, the pattern information of the trace is the pattern fusion of each trace data, the time of the trace is the latest time in all reply sequences, the distance information of the trace is the distance of the latest reply sequence in the reply sequence, and the azimuth information is the average azimuth of each trace; The step 42 comprises: If the response information of the points of the same mode are all complete, the point data with the largest response amplitude value among the points of the same mode are stored in the point database; If the response information of the traces of the same mode is incomplete, and the response sequence of each trace is within a 3dB response beam width, it is necessary to fuse the traces and store the fused traces in the trace database; wherein the time of the fused traces is the latest time in all response sequences, the distance information is the distance of the latest response sequence in the response sequence, and the azimuth information is the average azimuth of each trace; If the response information of the traces of the same mode are all incomplete, and the response sequence of each trace exceeds a 3dB response beamwidth, the trace with the largest response amplitude value among the traces of the same mode is stored in the trace database; If the response information of the dot trace of the same mode contains both complete response sequences and incomplete response sequences, and the dot trace amplitude of the complete response sequence is higher than that of other dot trace information, then other dot trace information is removed, and only the dot trace with the complete response sequence is stored in the dot trace database; If the response information of the traces of the same mode contains both complete response sequences and incomplete response sequences, and the trace amplitude of the complete response sequence is smaller than the trace amplitude value of the incomplete response sequence, it is necessary to confirm whether the sidelobe flag of the incomplete response sequence is valid. If the sidelobe flag is valid, it is considered to be a split target, and only the traces of the complete response sequence are stored in the trace database. Otherwise, the traces of the incomplete response sequence are stored in the trace database.

2. The method according to claim 1, characterized in that The step 1 comprises: If the distance of the original point exceeds the preset distance range, it will be removed; If the orientation of the original point trace exceeds the preset orientation range, it will be removed; If the response mode of the original point trace is any one of MA, MA / C, MS, M1, and M2, it will be stored in the point trace database of the corresponding mode.

3. The method according to claim 2, characterized in that The point trace database is updated in real time, and is arranged in ascending order according to the distance of the point traces, and is stored in sectors according to the orientation of the point traces.

4. The method according to claim 1, characterized in that: The step 2 comprises: Step 21: Traverse the points in the point database of different modes: If the distance difference between two points in the point database corresponding to the same mode is outside the first preset threshold range, the traversal continues; If the distance difference between two point traces in the point trace database corresponding to the same mode is within the first preset threshold range, the azimuth difference of the two point traces will continue to be judged. If the azimuth difference is outside the first preset threshold value, the traversal will continue; wherein the first preset threshold value is 1.5 times the 3dB width of the current transmit beam; Step 22: for the traces in the trace database of different modes after traversal, if the trace queues have different modes and are within the mode-related threshold range, mark them as a group of split traces of different answer modes; If the points have the same pattern and the same pattern code, they are marked as a group of split points with the same pattern; wherein the pattern code includes MA code, MS code, M1 code, and M2 code.

5. The method according to claim 4, characterized in that The step 3 comprises: For the split traces marked as different response modes, extract the first key parameters of each split trace and store them in the split trace response database; wherein the first key parameters include mode information, mode code information, distance and azimuth information, and time information of all response sequences of the trace; For the split traces marked as the same mode, the second key parameters of each split trace are extracted and stored in the split trace response database; wherein the second key parameters include the time of all response sequences, the amplitude information of the response code element, the sign bit of the response sequence and its confidence, the distance azimuth information and the sidelobe mark information.

6. The method according to claim 1, characterized in that The step 5 comprises: Step 51: Traverse all the traces in the trace database, and compare each trace with all the historical traces corresponding to the first two frames in the historical trace database; if the historical trace is within the preset area of ​​each trace, divide it into the trace queue of the preset area of ​​the trace; If there are multiple historical traces in the trace queue of the preset area, continue to screen them: if there are targets with the same pattern and code as the current trace in the historical traces, only the targets with the same pattern and code are retained, otherwise the trace queue of the preset area is deleted; Step 52: storing the dot trace data extracted from the dot trace queue of the preset area into the dot trace information correction database; wherein the dot trace data includes dot trace mode, mode code, dot trace orientation, dot trace distance, dot trace height, dot trace amplitude and mark information; Step 53: fetching the dot trace data from the dot trace information correction database respectively, and performing code / S mode address judgment according to the corresponding mode to complete error correction of the response information of the dot trace in the dot trace information correction database, thereby obtaining the corrected dot trace database.

7. The method according to claim 6, characterized in that The step 53 comprises: If the code / S mode addresses are the same, the altitude is judged. If both the current point trace and the historical point trace have altitude information, the altitude abnormality is judged. If the altitude change threshold is exceeded, the altitude information of the current point trace is corrected to the altitude information of the target in the previous frame. If the current trace is an S-mode trace and the historical trace data is not an S-mode trace, no response information error correction will be performed; If the dot trace mode is the same and the code is different, the code jump judgment is performed with the code information in the historical data. If the codes of the first two frames of historical data are the same, the code of the current dot trace is corrected to the code of the first two frames; otherwise, the code of the current dot trace remains unchanged.

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