Method for realizing cross-coverage-area target tracking in collaborative monitoring in S mode

Abstract

The invention belongs to the technical field of radar data processing, and discloses a method for realizing cross-coverage-area target tracking in cooperative monitoring in an S mode. The method comprises the steps that a plurality of adjacent secondary radar stations are networked to form a cluster, the coverage area of each secondary radar station in the cluster is allocated, a cluster network is established in the cluster, cooperative monitoring is conducted on a flying target, and blind compensation of a radar headspace blind area is achieved through cooperative management in the cooperative monitoring process. Some abnormal detection areas with poor monitoring performance are improved through collaborative management. According to the method, the problem of shortage of existing II / SI codes can be solved, the inquiry rate of the S-mode secondary radar is reduced, interference between response signals is reduced, the stability and continuity of target monitoring are effectively improved, meanwhile, blind compensation of a radar headspace blind area can be achieved, and the target monitoring quality of a specific area is improved.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of radar data processing, and in particular to a method for realizing cross-coverage target tracking in collaborative monitoring under S mode. Background Art

[0002] In order to ensure the continuity and reliability of secondary radar monitoring of aircraft, the site selection of secondary radar ground stations should take into account the overlap between the coverage areas of adjacent secondary radars to avoid blind spots. When an aircraft enters the overlapping coverage area, it will gradually move away from the coverage area of ​​the previous radar and enter the coverage area of ​​the next radar. In order to improve the continuity of target monitoring, the coordinated monitoring function of the secondary radar can be used to achieve a smooth transition and handover of the flying target between the coverage areas of the two radars, achieving a stable and continuous monitoring effect.

[0003] The 12-bit aircraft secondary code obtained by conventional secondary radar is not unique. The secondary code has limited capacity and can be reused, so one secondary code can correspond to more than one aircraft. Conventional secondary radar is upgraded to S-mode secondary radar, and conventional transponder is upgraded to S-mode transponder to form S-mode secondary radar system. The S-mode secondary radar system adds a 24-bit aircraft address code on the basis of the secondary code. ICAO regulations stipulate that the aircraft address code is unique, the address code cannot be reused, and one 24-bit address code can only correspond to one aircraft.

[0004] Air traffic control is currently mainly based on Mode S radars, whose detection and decoding reliability is widely recognized. The performance achieved by Mode S radars is related in particular to the fact that the radars are identified by aircraft through their II / SI codes (II being the acronym for Interrogator Identifier). In order to limit electromagnetic interference and therefore increase the reliability of radar transactions, Mode S radars lock the targets they manage within their coverage and area of ​​responsibility to their II / SI identities, preventing these targets from responding to non-selective Mode S interrogations.

[0005] The S-mode secondary radar system also adds a radar address code. Each radar has a 4-bit II address code or a 7-bit SI address code (referred to as II code or SI code). The value range of the II code is [0, 15]. Compared with the operating S-mode secondary radar, the II code capacity is insufficient, so the S-mode secondary radar introduces the SI code for capacity expansion. The value range of the SI code is [1, 63]. However, since some S-mode transponders in use are of a lower level and can only recognize II codes but not SI codes, the II code and SI code coexist in the current S-mode secondary radar system. An S-mode secondary radar can use the II code to define the radar address, or it can use the SI code to define the radar address, or it can use both the II code and the SI code to define the radar address.

[0006] Due to the limited number of address codes, in order to reduce asynchronous interference between secondary radars and utilize limited II codes or SI codes, a group of adjacent S-mode secondary radar ground stations can share one II code or SI code to form a cluster. The secondary radars in the cluster share and transfer target information within their respective power coverage ranges through collaborative monitoring, ensuring the continuity and stability of target monitoring.

[0007] The biggest difference between the S-mode secondary radar and the conventional secondary radar is that it uses roll-call interrogation, which avoids the synchronous interference and asynchronous interference problems caused by the all-call interrogation of the conventional secondary radar. However, the S-mode secondary radar still retains an all-call interrogation format to discover unknown new targets. In order to avoid the interference caused by the all-call interrogation format, the S-mode secondary radar locks on the known targets, and the locked targets no longer respond to the all-call interrogation. In the S-mode working mode, most of the targets in the air are known targets and are locked, and only a small number of unknown targets respond to the all-call interrogation, which greatly reduces the possibility of interference. Summary of the invention

[0008] The object of the present invention is to provide a method for realizing cross-coverage target tracking in cooperative surveillance under S mode, utilizing the characteristics that each aircraft in the S mode secondary radar system has a unique 24-bit address code and each radar has a radar address code (II code or SI code), through the grouping and clustering of adjacent radars, the allocation and sharing of II codes or SI codes, the division of radar power coverage maps, and network communication between radars, the number of inquiries of a single radar is reduced, the sharing of target information and the continuity of target surveillance are realized.

[0009] To achieve the above object, the present invention provides a method for implementing cross-coverage target tracking in cooperative surveillance under S mode, comprising the following steps: Step 1: Network several adjacent secondary radar stations to form a cluster. All secondary radar stations in the cluster share a single II code or SI code and use the same II code or SI code to send inquiries to the flying target. Step 2: Allocate the coverage area of ​​each secondary radar station in the cluster: According to the monitoring capabilities of all secondary radar stations in the cluster, use the coverage map making software to uniformly design and make a coverage map file. The coverage map file consists of a number of coverage units. The total number of coverage units in the coverage map file is equal to the total number of rows of latitude in the coverage map file multiplied by the total number of columns of longitude in the coverage map file. Each secondary radar station in the cluster allocates a data description bit to each coverage unit; When the data description bit is set to 1, it indicates that the secondary radar station is responsible for the coverage unit; When the data description bit is set to 0, it means that the secondary radar station is not responsible for the coverage unit; Step 3: Set up a cluster controller in each cluster, establish a cluster network in the cluster, and all secondary radar stations and cluster controllers in the cluster read the coverage map file; Step 4: Conduct collaborative monitoring of the flying target. The collaborative monitoring process includes network topology detection process, target collaborative monitoring process and data fusion process. Step 5: When a secondary radar station in the cluster identifies a flying target flying into the overhead blind zone, it requests support for flying target monitoring from other secondary radar stations in the cluster that are adjacent to the flying target. Other adjacent secondary radar stations continue to monitor the flying target and share the information of the flying target. When the flying target flies out of the overhead blind zone, the secondary radar station in the cluster resumes monitoring the flying target, maintaining continuous and uninterrupted monitoring of the flying target; Step 6: In the detection anomaly area where the flight target's track is unstable or not smooth, the cluster controller transfers the monitoring right of the detection anomaly area to the adjacent secondary radar station with overlapping coverage area.

[0010] Furthermore, the number of secondary radar stations forming the cluster in step 1 is 3-6.

[0011] Furthermore, the secondary radar station includes a transmitting signal module, a receiving signal module, a signal processing module, a data processing module, display and control software, collaborative processing software, coverage map making software, an inter-station network, and an intra-station network.

[0012] Furthermore, the coverage map file in step 2 includes a monitoring coverage area, a locking coverage area, and a data link coverage area.

[0013] Further, in step 4, according to the signal strength of the cluster network, the working modes of the secondary radar stations in the cluster include autonomous mode, distributed mode and centralized mode; When the cluster controller does not exist and the signal strength of the cluster network is weak, it is impossible to provide a stable cluster network and enter the autonomous mode. In the autonomous mode, the secondary radar station performs stand-alone processing. Each secondary radar station independently completes the acquisition and tracking of the flight target track within the coverage area of ​​the station and updates the target data list of the station. When the signal strength of the cluster network is stable and the cluster controller fails or does not exist, it enters the distribution mode. In the distribution mode, each secondary radar station in the cluster independently detects its network topology structure, and each secondary radar station independently completes the acquisition and tracking of the flight target track within the coverage area of ​​the station. Each secondary radar station independently receives the support data of the flight targets of other secondary radar stations, and at the same time sends the support data of the flight targets to other secondary radar stations that need to be monitored collaboratively for communication. All secondary radar stations in the cluster perform flight target data fusion processing and update the target data list of this station; When the signal strength of the cluster network is stable and the cluster controller exists, it enters the centralized mode. In the centralized mode, the cluster controller detects the network topology of the secondary radar stations in the cluster. The cluster controller receives the flight target track data obtained by all secondary radar stations, and sends the support data of the flight target to the secondary radar stations that need collaborative monitoring. The cluster controller performs flight target data fusion processing and updates the global target data list.

[0014] Furthermore, the track data includes track start data, track update data, track extrapolation data and track disappearance data.

[0015] Furthermore, in the centralized mode, the cluster controller coordinates all the secondary radar stations in the cluster to complete the target collaborative monitoring process. The cluster controller selects the maximum antenna scanning period of all the secondary radar stations in the cluster as the monitoring period. The cluster controller completes the following operations based on the data received from all the secondary radar stations: Step 7: When the flight target track starts, the track start data is sent to other secondary radar stations with the same coverage area but still without a start track; Step 8: When the flight target track is updated, the track update data is sent to other secondary radar stations with the same coverage area but still without initiating or maintaining tracks; Step 9: When the flight target track is extrapolated, the track extrapolation data is sent to other secondary radar stations for track extrapolation; Step 10: Clear the flight target when its track disappears.

[0016] Beneficial effect: The present invention provides a method for realizing cross-coverage target tracking in collaborative surveillance under S mode, utilizing the characteristics that each aircraft in the S mode secondary radar system has a unique 24-bit address code and each radar has a radar address code (II code or SI code), through the grouping and clustering of adjacent radars, the allocation and sharing of II codes or SI codes, the division of radar power coverage areas, and the collaborative surveillance and information sharing technology between radars, to solve the existing II / SI code shortage problem, reduce the interrogation rate of the S mode secondary radar, reduce the interference between the reply signals, and effectively improve the stability and continuity of target surveillance. At the same time, the present invention can also realize the blind spot filling of the radar overhead space and improve the target surveillance quality in a specific area. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a diagram of a collaborative monitoring network structure involved in an embodiment of the present invention; Figure 2 is a network structure diagram of a secondary radar station node involved in an embodiment of the present invention; Figure 3 is a conversion diagram between the autonomous mode, the distributed mode and the centralized mode involved in the embodiment of the present invention; Figure 4 is a distributed mode data flow diagram involved in an embodiment of the present invention; Figure 5 is a centralized mode data flow diagram involved in an embodiment of the present invention; Figure 6 It is a flow chart of a method for realizing cross-coverage target tracking in collaborative monitoring under S mode involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The preferred mechanism and implementation method of the present invention are further described below in conjunction with the accompanying drawings and specific implementation methods.

[0020] Secondary radar refers to a radar that performs another scan based on the original radar scanning data. The secondary radar station is a radio electronic positioning and identification system composed of an interrogation radar and a reply radar. The interrogation radar emits electromagnetic waves, and the reply radar (also known as a radar beacon) is triggered after receiving the interrogation electromagnetic waves and emits reply electromagnetic waves. The interrogation radar works according to the received reply electromagnetic waves to achieve identification and positioning. The interrogation radar of the secondary radar and the reply radar on the target work in coordination according to active scanning interrogation and passive reply. The interrogation radar is generally fixed on the ground, and the pulse of its scanning beam is encoded with an interrogation signal, and the reply pulse of the reply radar carries a code of its own code. The carrier frequencies of the interrogation pulse and the reply pulse are different, thus preventing the misreceiving of the transmitted wave.

[0021] The station target data list refers to the detailed information of all target tracks being monitored by the secondary radar station, including the relationship of each track between the secondary radar station and all other nodes in the cluster.

[0022] The global target data list refers to the detailed information of all target tracks being monitored by the cluster controller, including the relationship between each track between the cluster controller and all secondary radar stations in the cluster.

[0023] All nodes of the cluster include all secondary radar stations and cluster controllers in the cluster.

[0024] like Figures 1 to 6 As shown, the embodiment of the present invention discloses a method and technical solution for realizing cross-coverage target tracking in cooperative monitoring under S mode. Figure 1 A collaborative surveillance network structure diagram of a method for realizing cross-coverage target tracking in collaborative surveillance; Figure 2 The network structure diagram of the secondary radar station node of the method for realizing cross-coverage area target tracking in collaborative monitoring, the secondary radar station includes a transmitting signal module, a receiving signal module, a signal processing module, a data processing module, display and control software, collaborative processing software, coverage map making software, inter-station network, and intra-station network. Figure 3is a diagram of transitions between autonomous mode, distributed mode and centralized mode for a method of realizing target tracking across coverage areas in collaborative surveillance, Figure 4 is a distributed mode data flow graph, Figure 5 is a centralized mode data flow diagram involved in an embodiment of the present invention, Figure 6 The embodiment of the present invention relates to a flow chart of a method for implementing cross-coverage target tracking in collaborative monitoring under S mode. Example 1

[0025] The present invention provides a method for realizing cross-coverage target tracking in cooperative surveillance under S mode, comprising the following steps: Step 1: Network several adjacent secondary radar stations to form a cluster. All secondary radar stations in the cluster share a single II code or SI code and use the same II code or SI code to send inquiries to the flying target. Step 2: Allocate the coverage area of ​​each secondary radar station in the cluster: According to the monitoring capabilities of all secondary radar stations in the cluster, use the coverage map making software to uniformly design and make a coverage map file. The coverage map file consists of a number of coverage units. The total number of coverage units in the coverage map file is equal to the total number of rows of latitude in the coverage map file multiplied by the total number of columns of longitude in the coverage map file. Each secondary radar station in the cluster allocates a data description bit to each coverage unit; When the data description bit is set to 1, it indicates that the secondary radar station is responsible for the coverage unit; When the data description bit is set to 0, it means that the secondary radar station is not responsible for the coverage unit; Step 3: Set up a cluster controller in each cluster, establish a cluster network in the cluster, and all secondary radar stations and cluster controllers in the cluster read the coverage map file; Step 4: Conduct collaborative monitoring of the flying target. The collaborative monitoring process includes network topology detection process, target collaborative monitoring process and data fusion process. Step 5: When a secondary radar station in the cluster identifies a flying target flying into the overhead blind zone, it requests support for flying target monitoring from other secondary radar stations in the cluster that are adjacent to the flying target. Other adjacent secondary radar stations continue to monitor the flying target and share the information of the flying target. When the flying target flies out of the overhead blind zone, the secondary radar station in the cluster resumes monitoring the flying target, maintaining continuous and uninterrupted monitoring of the flying target; Step 6: In the detection anomaly area where the flight target's track is unstable or not smooth, the cluster controller transfers the monitoring right of the detection anomaly area to the adjacent secondary radar station with overlapping coverage area.

[0026] According to the signal strength status of the cluster network, the working modes of the secondary radar stations in the cluster include autonomous mode, distributed mode and centralized mode.

[0027] Autonomous mode: When the signal strength of the cluster network cannot support a stable cluster, the secondary radar station node chooses to enter the autonomous mode, performs stand-alone processing, independently completes the acquisition and tracking of flying targets within its own coverage area, and realizes track updates. This operating state often occurs when the secondary radar station is just turned on and has not yet entered stable operation.

[0028] Distributed mode: When the network is connected, the cluster is stable, and the cluster controller fails or does not exist, the secondary radar station enters the distributed mode. Each secondary radar station completes the acquisition and tracking of the flying targets in the coverage area of ​​the station, and realizes the track update. At the same time, it communicates with other secondary radar stations in the cluster to complete the network topology update. For the data flow of the distributed mode, see Figure 4 .

[0029] Centralized mode: When the network is connected, the cluster is stable, and the cluster controller exists, the secondary radar station enters the centralized mode, communicates with each secondary radar station node in the cluster, completes the network topology update, and the cluster controller is responsible for selecting a specific secondary radar station to complete the acquisition and tracking of the flight target and realize the track support function. The centralized mode data flow is shown in Figure 5 .

[0030] The autonomous mode, distributed mode and centralized mode will switch automatically according to the actual situation. For the switching conditions, see Figure 3 .

[0031] Network topology detection process: All nodes in the cluster (all secondary radar stations and cluster controllers) regularly detect the network topology, set the working state according to the network topology, and select the corresponding working parameters. For the centralized mode, the network topology is detected by the cluster controller, and the state is changed when the topology changes; for the distributed mode, all secondary radar stations in the cluster detect the network topology separately, select the working state according to the network topology, otherwise enter the autonomous mode; when a secondary radar station is connected to the cluster network, the new radar station notifies all other secondary radar stations to update their respective network topologies.

[0032] Target collaborative monitoring process: For the distributed mode, the secondary radar station monitors the flight target independently and updates the flight target status. For the centralized mode, the cluster controller maintains the global roll call list and coordinates all nodes in the cluster to complete the flight target monitoring and complete the processing of track initiation, track update, track extrapolation and track disappearance.

[0033] Data fusion process: For centralized mode, target data of all radars are sent to the cluster controller, which fuses the multi-radar track data and maintains a global roll call list; for distributed mode, each secondary radar station receives target data from other secondary radar stations separately and performs track data fusion. Example 2

[0034] This embodiment is basically the same as Embodiment 1, except that three adjacent S-mode secondary radar stations are first selected: Zhangjiajie Station, Changsha Station and Wuhan Station to form a cluster. Zhangjiajie Station is about 306 kilometers away from Changsha Station, Changsha Station is about 304 kilometers away from Wuhan Station, and Wuhan is about 414 kilometers away from Zhangjiajie Station. The surveillance areas of the three radar stations have single-station surveillance areas, double-station overlapping surveillance areas and three-station overlapping surveillance areas at each altitude, which can well meet the business needs of collaborative surveillance networking. Functional testing includes: cluster coverage management, network collaborative management, target collaborative management, system master and standby management, radar address code management and other contents.

[0035] In order to reduce the impact of the collaborative surveillance network on the original secondary radar equipment, two networks are designed, namely the intra-station network of the secondary radar station and the inter-station network of the collaborative surveillance. The two networks are physically separated to avoid mutual impact. At the same time, in order to improve the robustness of the collaborative surveillance network, all software and hardware devices adopt a dual backup design of primary and backup. If the primary device fails, it will switch to the backup device in real time. For the specific network structure, see Figure 2 . Figure 2 The present invention is a network structure diagram of the nodes of a secondary radar station for realizing a method for tracking targets across coverage areas in collaborative surveillance. The nodes of the secondary radar station include a transmitting signal module, a receiving signal module, a signal processing module, a data processing module, display and control software, collaborative processing software, coverage map making software, an inter-station network of the secondary radar station, and an intra-station network of the secondary radar station.

[0036] In this experiment, the specific use of II / SI codes is agreed upon: when the cluster is in autonomous mode, the experimental radar stations use their own original II / SI codes; when the cluster is in distributed mode or centralized mode, the cluster uses the experimental II code together. The specific definitions are shown in Table 1.

[0037] Table 1 Allocation of radar codes in the cluster

[0038] The coverage areas of the three radars in the cluster are allocated. The coverage map making software uniformly designs and makes cluster coverage map files according to the positions and antenna heights of the three secondary radars. The coverage files include monitoring coverage maps, lock coverage areas, data link coverage areas, etc. Each secondary radar in the cluster allocates a data description bit to each coverage unit. If the data description bit is set to "1", the radar station is responsible for this unit; if the data description bit is set to "0", the radar station is not responsible for this unit. In the overlapping coverage area of ​​the radar, the coverage unit is preferentially allocated according to the radar coverage capability.

[0039] The cluster controller's management of the cluster during the collaborative monitoring process includes the network topology detection process, the target collaborative monitoring process, and the data fusion process.

[0040] Network topology detection process: All nodes in the cluster, including all secondary radar stations and cluster controllers, need to regularly detect the network topology, and then set the working state according to the network topology and select the corresponding working parameters. For the centralized mode, the network topology is detected by the cluster controller. When the cluster network topology changes, the cluster controller sends a message to each radar station to perform state transition; for the distributed mode, all secondary radar stations in the cluster detect the network topology and stability separately. If the network is stable, the working state is selected according to the network topology, otherwise it enters the autonomous mode; when the secondary radar station is connected to the network, the new radar station notifies all other secondary radar stations to update their respective network topologies.

[0041] Target collaborative monitoring process: For the distributed mode, the secondary radar station monitors the target independently and updates the target status. For a specific secondary radar station, the target data list of this station refers to the detailed information of all target tracks being monitored by the secondary radar station, including the relationship between each track between the secondary radar station and all other nodes in the cluster. For the centralized mode, the cluster controller maintains the global target data list, which refers to the detailed information of all target tracks being monitored by the cluster controller, including the relationship between each track between the cluster controller and all secondary radar stations in the cluster. The cluster controller coordinates all nodes in the cluster to complete target monitoring. The cluster controller selects the maximum antenna scanning cycle of all nodes as the monitoring cycle, and then completes the following operations based on the data received from the node: (1) Track start: Send "track data message" to other nodes with the same coverage area but still have not started the track; (2) Track update: Send "track data message" to other nodes with the same coverage area but still have not started or maintained the track; (3) Track extrapolation: Send "track data message" to other nodes with track extrapolation; (d) Track disappearance: Clear the target.

[0042] Data fusion process: For the distributed mode, each secondary radar station receives the flight target track data from other secondary radar stations separately, performs track data fusion, and maintains a target data list for this station. For the centralized mode, the flight target data of all secondary radar stations are sent to the cluster controller, which performs multi-radar track data fusion and maintains a global target data list; the cluster controller first receives the flight target track data sent by each secondary radar station from the cluster network, performs coordinate conversion and time alignment, then performs target data fusion processing, and finally updates the global target data list.

[0043] According to the signal strength status of the cluster network, the cluster working mode includes centralized mode and distributed mode. At the same time, each cluster working mode is divided into different working states according to the network topology. Each cluster node can set appropriate operating parameters, mainly including: (1) power coverage map for monitoring, locking and data link; (2) II and SI codes of each radar station; (3) startup configuration of this node, including mode alternation method and radiation power setting.

[0044] The secondary radar stations in the cluster monitor collaboratively, and each secondary radar station shares a cluster power coverage map. When the target crosses the radar overlapping coverage area, the designated radar set in the coverage map completes the monitoring and tracking of the target. Due to the optimization of the coverage map setting: the problem of reduced target monitoring capability at the edge of radar coverage is avoided, and the target monitoring quality of collaborative monitoring is significantly higher than that of independent radars.

[0045] The coordinated monitoring of secondary radar stations within the cluster is also very helpful in making up for the blind spots of the secondary radar stations. In this test, it was observed that there was a civil route crossing the blind spot of Wuhan Station from northeast to southwest (the target entered from northeast to southwest at an altitude of 8412 meters). When the flying target entered the blind spot, extrapolation appeared and then disappeared. After the flying target passed through the blind spot, it was monitored normally again. There was a time interval of about 46 seconds when this target passed through the blind spot of Wuhan Station and could not be monitored. After Wuhan Station joined the cluster, the blind spot of Wuhan Station was in the monitoring area of ​​Changsha Station. When the target flew into the blind spot of Wuhan Station, Wuhan Station could request target support from Changsha Station and continue to monitor the target, keeping the target monitoring continuous and uninterrupted. The data recorded by the field test was analyzed. On the day of data recording, from 18:25:48 to 20:39:00, the three test radar stations observed a total of 52 batches of targets crossing the blind spots of each station. After being processed by the target collaborative management method, the target monitoring was continuous and uninterrupted.

[0046] Collaborative monitoring of radars within a cluster helps to improve the target quality in some areas with poor monitoring performance. In such areas, the target track is unstable or not smooth. In order to effectively improve the monitoring performance in abnormal areas, a target collaborative management method with active collaborative support is adopted to effectively improve the target monitoring performance. In the experiment, the actual detection data of Zhangjiajie Station was observed, and it was found that there was a detection anomaly area, so a fan-shaped detection anomaly area was set at this location. When the target entered this area, it requested target monitoring support from Wuhan Station. At 18:30:04, the target was observed to enter this abnormal area, and at 18:32:03, the target flew away from the detection anomaly area. The track quality after target collaborative processing was significantly improved. From 18:25:48 to 20:39:00, 31 batches of targets were observed to cross the detection anomaly area of ​​Zhangjiajie Station. After target collaborative processing, the target monitoring performance was significantly improved.

[0047] The present invention provides a method for realizing cross-coverage target tracking in cooperative monitoring under S mode. The method utilizes the characteristics that each aircraft in the S mode secondary radar system has a unique 24-bit address code and each radar has a radar address code (II code or SI code). By grouping and clustering adjacent radars, allocating and sharing II codes or SI codes, dividing radar power coverage areas, and cooperative monitoring and information sharing technologies between radars, the existing II / SI code shortage problem is solved, the interrogation rate of the S mode secondary radar is reduced, the interference between reply signals is reduced, and the target monitoring stability and continuity are effectively improved. At the same time, the present invention can also realize the blind spot filling of the radar head space blind spot and improve the target monitoring quality in a specific area.

[0048] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for realizing cross-coverage target tracking in cooperative surveillance under S mode, characterized in that: The following steps are involved: Step 1: Network several adjacent secondary radar stations to form a cluster. All secondary radar stations in the cluster share a single II code or SI code and use the same II code or SI code to send inquiries to the flying target. Step 2: Allocate the coverage area of ​​each secondary radar station in the cluster: According to the monitoring capabilities of all secondary radar stations in the cluster, use the coverage map making software to uniformly design and make a coverage map file. The coverage map file consists of a number of coverage units. The total number of coverage units in the coverage map file is equal to the total number of rows of latitude in the coverage map file multiplied by the total number of columns of longitude in the coverage map file. Each secondary radar station in the cluster allocates a data description bit to each coverage unit; When the data description bit is set to 1, it indicates that the secondary radar station is responsible for the coverage unit; When the data description bit is set to 0, it means that the secondary radar station is not responsible for the coverage unit; Step 3: Set up a cluster controller in each cluster, establish a cluster network in the cluster, and all secondary radar stations and cluster controllers in the cluster read the coverage map file; Step 4: Conduct collaborative monitoring of the flying target. The collaborative monitoring process includes network topology detection process, target collaborative monitoring process and data fusion process. Step 5: When a secondary radar station in the cluster identifies a flying target flying into the overhead blind zone, it requests support for flying target monitoring from other secondary radar stations in the cluster that are adjacent to the flying target. Other adjacent secondary radar stations continue to monitor the flying target and share the information of the flying target. When the flying target flies out of the overhead blind zone, the secondary radar station in the cluster resumes monitoring the flying target to maintain continuous and uninterrupted monitoring of the flying target; Step 6: In the detection anomaly area where the flight target's track is unstable or not smooth, the cluster controller transfers the monitoring right of the detection anomaly area to the adjacent secondary radar station with overlapping coverage area.

2. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 1, characterized in that: The number of secondary radar stations forming the cluster in step 1 is 3-6.

3. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 1, characterized in that: The secondary radar station includes a transmitting signal module, a receiving signal module, a signal processing module, a data processing module, display and control software, collaborative processing software, coverage map making software, an inter-station network, and an intra-station network.

4. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 1, characterized in that: The coverage map file in step 2 includes the surveillance coverage area, the lock coverage area, and the data link coverage area.

5. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 1, characterized in that: In step 4, according to the signal strength of the cluster network, the working modes of the secondary radar stations in the cluster include autonomous mode, distributed mode and centralized mode; When the cluster controller does not exist and the signal strength of the cluster network is weak, it is impossible to provide a stable cluster network and enter the autonomous mode. In the autonomous mode, the secondary radar station performs stand-alone processing. Each secondary radar station independently completes the acquisition and tracking of the flight target track within the coverage area of ​​the station and updates the target data list of the station. When the signal strength of the cluster network is stable and the cluster controller fails or does not exist, it enters the distribution mode. In the distribution mode, each secondary radar station in the cluster detects its network topology structure independently, and each secondary radar station independently completes the acquisition and tracking of the flight target track within the coverage area of ​​the station. Each secondary radar station independently receives the support data of the flight targets of other secondary radar stations, and sends the support data of the flight targets to other secondary radar stations that need to be monitored collaboratively for communication. All secondary radar stations in the cluster perform flight target data fusion processing and update the target data list of this station; When the signal strength of the cluster network is stable and the cluster controller exists, it enters the centralized mode. In the centralized mode, the cluster controller detects the network topology of the secondary radar stations in the cluster. The cluster controller receives the flight target track data obtained by all secondary radar stations, and sends the support data of the flight target to the secondary radar stations that need collaborative monitoring. The cluster controller performs flight target data fusion processing and updates the global target data list.

6. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 5, characterized in that: Track data includes track start data, track update data, track extrapolation data and track disappearance data.

7. The method for implementing cross-coverage target tracking in collaborative surveillance according to claim 6, characterized in that: In the centralized mode, the cluster controller coordinates all secondary radar stations in the cluster to complete the target collaborative monitoring process. The cluster controller selects the maximum antenna scanning period of all secondary radar stations in the cluster as the monitoring period. The cluster controller completes the following operations based on the data received from all secondary radar stations: Step 7: When the flight target track starts, the track start data is sent to other secondary radar stations with the same coverage area but still without a start track; Step 8: When the flight target track is updated, the track update data is sent to other secondary radar stations with the same coverage area but still without initiating or maintaining tracks; Step 9: When the flight target track is extrapolated, the track extrapolation data is sent to other secondary radar stations for track extrapolation; Step 10: Clear the flight target when its track disappears.

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