Method for determining the quality of a radar tracking operation

Abstract

The invention relates to a method for determining the quality of a tracking operation of a moving object (6) by means of a first radar (4b). The aim of the invention is to achieve high tracking reliability. To achieve this aim, a movement path (8a, 8b) of the object (6) is created from tracking data which another radar (4a) has acquired from a tracking operation (32) of the object (6), and a radar simulation system (10b) creates, on the basis of data relating to the movement path (8a, 8b), a simulation (36) of a tracking operation of the object (6) carried out by the first radar (4b), including a tracking quality of the simulated tracking operation.

Description

[0001] Methods for determining the quality of radar tracking

[0002] The invention relates to a method for determining the quality of tracking a moving object by a first radar.

[0003] In large-scale airspace surveillance or the targeted tracking of a flying object in the airspace, it may be necessary to transfer an object being tracked by one radar to another, for example, if the object leaves one radar area and enters another, or if an obstruction blocks a radar's view of the flying object. In a radar network of spatially distributed radars, a military radar network reports the movement path of a flying object only to the network by the radar that achieves the highest tracking quality for that movement path. Other radars in the network also track the object by locally tracking its movement path, but this tracking is not reported to the network due to its lower tracking quality.As soon as one of these local tracking systems exhibits a tracking quality higher than that of the radar transmitting its tracking data to the radar network, the other radar will report the movement path from its local tracking system to the radar network, thereby assuming reporting responsibility for that movement path. The previously responsible radar will then cease transmitting its data to the radar network for that movement path. The path handover from one radar to another can be performed manually by a controller or automatically using flight route information, altitude, or IFF code.

[0004] It is an object of the present invention to provide a method for making the tracking of a moving object more reliable. This object is achieved by a method of the type mentioned at the outset, in which, according to the invention, a motion path of the object is created from tracking data obtained by a further radar from tracking the object, and a radar simulation system uses data from the motion path to create a simulation of the tracking of the object along this motion path by the first radar, including a tracking quality of the simulated tracking.

[0005] The invention is based on the premise that, until now, several radars in a radar network have illuminated the object and each determined the tracking quality of its own tracking of the object from the received signals. However, the active illumination of the object by multiple radars makes them visible and potentially exposes them to increased danger. This disadvantage can be overcome if the tracking quality of the first radar can also be determined while the first radar is inactive. The first radar can be any radar, for example, a radar from a radar network. If the object's movement path is known, the tracking quality of the first radar, and optionally also of other radars—for example, one, several, or all radars in a radar network—can be determined by simulating the tracking process. The tracking simulation can be performed while the radars are inactive.

[0006] Tracking quality, that is, the quality of a first radar's tracking of a moving object, allows conclusions to be drawn about whether the first radar would be suitable for tracking the object. For example, the tracking quality of the simulated tracking can be compared with the actual tracking quality of the second radar. If the simulated tracking quality is higher than the actual tracking quality of the second radar, the tracking can be handed off from the second to the first radar without the first radar needing to be active in the meantime. The simulation and determination of tracking quality can also be performed with a passive first radar, so that the radar's location is not revealed by its activity. The same applies to multiple radars, such as radars in a radar network, so that in the best-case scenario, the entire radar network, except for the second radar currently tracking, can remain passive.It is sufficient for only the second radar to be active until the handover. This makes tracking the object safer, as the radars' passivity prevents them from being detected by the second radar and thus potentially endangered. It is advantageous for the first radar to be passive during the simulation and determination of the tracking quality of the simulated tracking. For example, of the two radars, only the one generating the real tracking data will actively illuminate the object. The first radar—like the other radars in the network—can remain passive and is therefore less visible. If a handover from the second to the first radar is planned, the first radar can be activated. The second radar can then end its active tracking.Based on the object's movement path determined by the first radar, it can then perform a simulation and determine its own tracking quality for the simulated tracking, thus taking over the role previously held by the first radar. However, it is not necessary to keep the first radar passive throughout the entire tracking process. It is sufficient to deactivate the first radar in hazardous situations and run the simulation.

[0007] The simulation can be performed using data from the object's path, although portions of the path or its data are sufficient. For example, only individual points along the path are used to determine how the first radar would detect the object at that point. Generally, the simulation can be performed using lookup tables or mathematical methods that can reproduce radar behavior and may be derived from the technical specifications of the first radar. Empirical models derived from the past behavior or performance of the first or another radar can also be used. The simulation need not be a simulation of tracking along a continuous path; it can focus on individual locations of the tracked object, or generally on only a portion of its path.In the simulation, for example, the visibility of the object at a point or within a movement path, it is not necessary to determine all tracking characteristics. It is sufficient to determine one or more selected tracking criteria and use them as a tracking simulation. The radar simulations are expediently designed so that each radar relates the simulation to itself, i.e., simulates how it would track the object from its own perspective. Since the radars' views and technical specifications are generally different, the simulations are also different and specific to the respective radar. For each simulation, the tracking quality of the simulated tracking can be determined, expediently over the entire movement path or at least over a portion of the movement path visible to the radar to which the simulation refers.Tracking quality can be described as simulated tracking quality. Tracking quality indicates the level of accuracy the radar would achieve when tracking an object along its predicted future path. Tracking quality can be determined by the first radar and, in particular, by each radar in a radar network for its own simulation. Advantageously, all of the multiple radars in the radar network determine the tracking quality for a path segment. The tracking qualities of each radar can be transmitted to the radar network, advantageously in the same format in which the next radar transmits its current, real-world tracking quality to the radar network.

[0008] The invention also relates to a method for transferring radar tracking of a moving object from a further radar to a first radar. According to the invention, a simulation of the tracking of the object performed by the first radar, including the tracking quality of the simulated tracking, is created from tracking data that the further radar has determined from tracking the object, and the tracking is transferred to the first radar.

[0009] The invention further relates to a method for operating a radar network comprising at least a first and a further radar, in which a moving object is tracked by the further radar. According to the invention, a radar simulation system creates a simulation of the tracking of the object by the first radar from tracking data obtained by the further radar from tracking the object, including a tracking quality of the simulated tracking.

[0010] The first and subsequent radars can be part of a radar network. The radar network can also include additional radars, a countermeasures system, and / or a fire control system. The radars can be mobile radars on a vehicle and / or stationary radars on a building. The object can be an aircraft or a land or water vehicle. The path of movement can be a radar track of one or more radars from the object. The subsequent radar tracks the moving object. The first radar can be any radar, for example, from a radar network. Tracking is usually active; the radar illuminates the object with radar radiation and receives the reflected radiation. From the received radar signal, a radar track, or path of movement of the object, can be created, indicating the object's past positions. This path of movement can be referred to as the actual path of movement or the past path of movement.It can be transmitted from the actively tracking radar to the radar simulation system and / or into the radar network, making it available to the radar simulation system and / or all radars in the radar network. From the motion path or tracking data of the object's track, one radar, several radars, or all radars in a radar network can create a simulation of the tracking along this motion path.

[0011] The first radar can contain a radar simulation system or be connected to one. Both possibilities are described below as if the radar simulation system is part of the radar. The radar simulation system can perform the tracking simulation and determine the simulated tracking quality. It is advantageous if the radar simulation system and / or the radars in a radar network include a converter that translates the tracking data arriving from other radars into the data system of the receiving radar, e.g., regarding formatting, unit system, coordinate system, and / or location. This is because it is not uncommon for the radars in a radar network to be of different designs and not compatible for data exchange without a converter. From the tracking data—which may have been converted—each radar can independently create its own tracking simulation of the object.

[0012] In an advantageous embodiment of the invention, the tracking quality of the simulated tracking by the first radar is compared with the actual tracking quality of the tracking by the second radar, and this comparison determines which radar continues tracking the object. The transfer of actual tracking can occur when the quality of the simulated tracking by the first radar is higher than the actual tracking quality of the second radar. The comparison expediently relates to the same spatial or temporal segment of the object's path. It is also possible for a transfer to occur only when the quality of the simulated tracking by the first radar is a predetermined amount higher than the tracking quality of the second radar. This, too, is generally referred to as higher tracking quality in the following.

[0013] It can happen that a previously simulated tracking quality for the first radar does not match the actual tracking quality of that radar during a given period. If a tracking handover is planned, for example, because the simulated tracking quality of the first radar is higher than the actual tracking quality of the second radar, it is advantageous for the first radar to actively track the object simultaneously with the second radar. This means the object is actively illuminated by both radars before the handover takes place. During this transition period, the first radar can then determine its actual tracking quality and compare it to that of the second radar. If the tracking quality of the first radar is higher than that of the second radar, tracking can be transferred from the second radar to the first radar.If the actual tracking quality determined after activation of the first radar is lower than that of the second radar, it may be advisable not to carry out the planned handover. The handover can therefore initially be a planned or intended handover. It can be made into an actual handover if the actual tracking quality of the first radar meets the requirements for an actual handover. One requirement might be that the actual tracking quality of the first radar exceeds that of the second radar.

[0014] However, it is also possible to implement a planned handover even if the actual tracking quality of the first radar is lower than that of the subsequent radar. If the subsequent radar is to be protected from attack and, for example, if active tracking needs to be terminated as quickly as possible, active tracking can be handed over to the radar in the network that has the next best tracking quality, or more generally, a tracking quality that meets at least one predetermined criterion.

[0015] Another scenario could be a countermeasures scenario where a handover to a radar launcher might be beneficial even if another radar offers better tracking accuracy, but a handover within a critical time interval should be avoided. The handover to the radar launcher can occur before the critical time interval, even if it doesn't have the best tracking accuracy within the radar network. Therefore, it is advantageous to consider the countermeasures timing when making a handover decision.

[0016] It is also possible that a radar, such as a radar launcher, has the best tracking capability, but this capability needs to be protected from potential attacks and therefore should remain passive. In this case, the radar is handed off to another radar with lower tracking capability. It is therefore advantageous to consider the type of radar in the handover decision.

[0017] It may also happen that a comparison of the actual tracking capabilities of the radars in question is not possible, for example, because the other radar has already been deactivated or is defective. In this case, it can be useful to compare the actual tracking capability of the first radar with the previously simulated tracking capability of the first radar. If the actual tracking capability is lower than the simulated tracking capability of the radar, it may be advisable not to carry out the planned handover and instead transfer the tracking capability to another radar. The comparison should ideally cover the same time period. This period can be a future timeframe for the simulation and the current timeframe for the actual tracking. Based on this comparison, a decision can be made as to which radar the tracking capability should be transferred.

[0018] If the first radar activates the object's illumination based on a good simulation, but the actual tracking accuracy of the first radar falls short of that of the second radar, the first radar would cease illuminating the object, and tracking would remain with the second radar. However, the first radar would again simulate incorrectly, again achieving a better result. A handover would be planned, but after the first radar's activation, this handover would be rejected again due to the re-detected simulation error. This can lead to the first radar being activated and deactivated repeatedly, for example, if the simulation error exceeds a tolerance band within which no activation occurs. To avoid this scenario, it is advisable to compare the tracking accuracy of the simulated tracking of a radar with the subsequent tracking accuracy of the same radar's actual tracking.If a simulation error is detected, the simulation can be adjusted to the actual tracking. It is also advantageous if the subsequent radar compares its actual tracking with the simulation for its future tracking and corrects any simulation errors. The same applies to all radars in the radar network that take over actual tracking during a given time period.

[0019] Generally, the handover decision from one radar to another can be made by a central unit in the radar network, for example, a fire control center or a fire control radar. The handover decision can be made automatically, depending on tracking capabilities, or manually, e.g., by a commander.

[0020] After the handover, the first radar tracks the moving object, ideally by actively irradiating it with radar radiation, and transmits its real-time tracking data to the radar network so that the other radars can create a simulation. The first radar then becomes the second radar. Its real-time tracking accuracy can now be compared with at least one other simulated tracking accuracy from another radar in the network, and this comparison allows a decision to be made as to whether the other radar in the network should take over the tracking from the first, now second, radar.

[0021] Another advantageous embodiment of the invention provides that a prediction of a future movement path of the object is created from the tracking data obtained by the additional radar from tracking the object, and that the radar simulation system uses data of the future movement path to create a simulation of a future tracking of the object performed by the first radar, including a tracking quality of the simulated tracking.

[0022] This prevents a tracking gap. If the tracking quality of the second radar suddenly drops, for example due to an obstruction, the first radar takes over when its tracking quality is higher. However, this handover only occurs if the second radar has already lost tracking or is only tracking with reduced quality. It is therefore desirable to know the tracking quality of the first and / or second radars in advance. By predicting the object's path, simulating the tracking, and determining the tracking quality during this simulated tracking, the expected tracking quality for a future path of the object is already known.The simulation of tracking along the future path of movement and the determination of the tracking quality of the simulated future tracking can be performed by both the first and the second radar. If the simulated tracking quality of the second radar falls below that of the first radar for the same tracking time segment or the same trajectory segment of the object, a handover can be predetermined, even before the tracking quality of the currently active second radar deteriorates. The handover can occur even before the tracking quality of the second radar is significantly reduced. This also contributes to making the tracking of a moving object safer.

[0023] It is possible for the second radar to generate the prediction and make it available to the first radar, and in particular to all radars in a radar network. It is also possible for a radar simulation system within a radar network to serve as a prediction center, generating and providing the prediction for all radars. The radar simulation system can be part of the first radar, the second radar, or another radar altogether, or it can operate independently of any radar, especially if high computing power is required for the prediction and high bandwidth is available for data transmission within the radar network.

[0024] The predicted motion path can be a track that the object has not yet traversed at the time of prediction, but is likely to traverse. The predicted motion path conveniently includes the object's position, direction, and velocity, which are summarized in a vector track in space or a one-dimensional vector space.

[0025] When multiple radars in the radar network each generate their own prediction of the object's future trajectory and, in particular, use it for their own simulations, it is advantageous for all predicting radars to operate with a uniform prediction algorithm so that all predictions are as similar as possible. If they are not sufficiently similar, the simulations will be based on different predicted trajectories and may not be adequately comparable. Therefore, it is advantageous if the radars or the radar simulation system have the same prediction unit and / or if the prediction units operate with the same prediction algorithm, so that identical tracking data of the object's flight path result in at least substantially the same predicted future trajectories.

[0026] In general, the simulation of object tracking can be performed based on the prediction. As with the prediction itself, this simulation can be executed by a radar network simulator for multiple radars, one for each radar. However, it is advantageous if each of the radars in a radar network performs the simulation independently based on the prediction, especially the additional radar that transmitted the real data to the radar network.

[0027] Advantageously, the prediction of an object's future trajectory incorporates its technical properties and, in particular, the resulting possible maneuvers, ideally including their probabilities. These technical properties can vary from object to object, such as its movement capabilities (i.e., its maneuverability), potential speed (e.g., maximum speed), possible accelerations and / or flight characteristics, as well as its typical behavior (e.g., escape behavior, movement patterns, and / or reaction times). It is also advantageous to include the object's past maneuvers and their subsequent maneuvers, along with their probabilities, in the prediction. This improves the accuracy of the prediction.

[0028] Activating the first radar makes it highly visible. To reduce this visibility, it is advantageous if, upon activation, the first radar directs its beam only onto the object's current location and a predetermined near-future area along its predicted path of movement. Prediction reveals the object's current location and its near-future position. Therefore, it is sufficient to illuminate only this area, minimizing the radar's visibility outside of it.

[0029] When comparing tracking capabilities, it is possible to compare the simulated tracking quality of the first radar with the actual tracking quality of the second radar. However, this approach has the disadvantage that the comparison can only be made retrospectively up to the present time. A pre-planned handover, on the other hand, can take place if the simulated tracking quality of the first radar is compared with the simulated tracking quality of the second radar. The time period being compared can lie in the future, allowing a handover time to be determined in advance.

[0030] It is advantageous to determine a future point in time for handing off the tracking of the object from the secondary to the primary radar based on the tracking quality. For example, both the primary and secondary radars can determine the tracking quality for the same segment of the object's path in their simulations. If the simulated tracking quality of the primary radar exceeds that of the secondary radar at a future point in time, this point in time can be selected as the handover point. It is also possible to choose a handover point that is dependent on this future point in time, i.e., a predetermined time relative to it. The chosen handover point lies in the future, allowing for an orderly handover at the optimal time without any gaps in tracking. The handover point can also be the point in time of a planned or preliminary handover.At this point, for example, the first radar can be activated. The actual tracking capabilities of the radars can be compared, and the planned handover can be implemented. The simulation with tracking capabilities can be repeated regularly. Tracking capabilities and the handover time can change from simulation to simulation, so the handover itself—that is, which radar is used—and the handover time can also change.

[0031] Another aspect is the type of radar in the radar network. Depending on the radar, its technical capabilities for tracking the object vary. This can be taken into account when determining the tracking quality, including the technical characteristics of the other radars. Such capabilities can include the frequency channels used and / or configurations employed, such as the selected operating mode, the transmission power, and / or the direction of the main beam adapted to the terrain. A radar malfunction or atmospheric attenuation can also be considered. The technical capabilities can also include statistical characteristics of the radar, such as noise behavior and / or beam shape.

[0032] Depending on location and weather conditions, the visibility of an object can vary from radar to radar. This parameter is also advantageously incorporated into the determination of tracking quality. Visibility can include a viewing angle or ROS (Radar Cross Section) from the radar to the object, for example, relative to its current flight direction. Landscape features between the radar and the object and / or clutter effects can also be taken into account. Landscape features can be derived from a terrain model combined with the location of the radar in question. Clutter effects also influence visibility. These can be obtained from a clutter map, which can be actively measured by the radar. Since active radar transmission makes its location visible, it is advantageous to limit the activity to a short period.Visibility can also be affected by the effects of the first Fresnel zone of the radar in question. These can impair the visibility of an object flying, for example, close to the horizon.

[0033] While the second radar is actually tracking the object, the first radar simulates its future tracking of the object along its current and / or future path of movement. This simulation includes the active illumination of the object by the first radar. The determined tracking quality of the first radar refers to the simulated tracking of the object when the first radar is actively illuminated. Since active illumination by a real tracking radar significantly increases its visibility, it is advantageous to also consider passive tracking. If it is possible to track the object with sufficient quality in a passive state, this possibility should be included in the simulation of the real tracking quality. For example, the object could be illuminated by another active radar source, making it sufficiently visible to the first radar.The radar emitter can be another radar in the radar network or a less vulnerable emitter. The simulation—and the resulting tracking quality of the simulated tracking—advantageously includes a simulation of passive, real-world tracking of the object by the first radar. For tracking handover, it is not necessary for the tracking quality of the first radar to be higher than that of the second radar if the second radar is actively illuminating the object. It is sufficient if the tracking quality is predetermined to be high enough for reliable tracking of the object. This design is particularly advantageous when the radar is part of a larger unit, such as a launcher unit, which requires special protection.

[0034] If the object's visibility is low, it can be advantageous for at least two radars in the radar network to actively track the object and for the prediction to be generated from a data fusion of the tracking data from both radars. Ideally, the radars are spaced apart so that they transmit their signals to the object from different directions.

[0035] To hand over tracking of the object from the secondary radar to the primary radar, minimum tracking quality criteria must be met by the primary radar. One such minimum criterion could be that the tracking quality maintains a minimum level and / or an average value over a predefined tracking segment. The minimum quality can be defined by a value from a filter output of the primary radar. It can also specify a minimum visibility level that must be maintained, such as a level of visibility required for reliable tracking. For airspace surveillance, it is advantageous to ensure tracking quality above a minimum value or a minimum average value across the entire tracking segment. For countermeasures, it is beneficial for the tracking quality to be high before the countermeasures are initiated, for example, with a minimum level in a critical path area.

[0036] In a radar network, particularly during combat situations, a radar may suddenly fail. This should be detected as quickly as possible so that a combat strategy can be rapidly adapted to the new situation. Rapid detection of a radar failure or defect can be achieved by using radar tracking quality data as the heartbeat of each radar within the radar network.

[0037] The invention also relates to a radar simulation unit for connection to a radar. The connection can be a plug-and-play connection, a connection permanently installed in a radar unit, or another type of connection. To achieve high tracking reliability, the radar simulation unit, according to the invention, includes a simulator for simulating the tracking of an object by the first radar along a motion path determined by another radar and for determining the tracking quality of the simulated tracking.

[0038] Furthermore, it is advantageous if the radar simulation system includes a predictor for predicting the future motion path of an object from tracking data from another radar. In this embodiment, it is useful if the simulator is prepared to simulate tracking the object along its future motion path by the first radar and also to determine the tracking quality of the simulated future tracking. A radar can be equipped or retrofitted with such a radar simulation unit, and a radar network can be equipped with one radar simulation unit for each of several radars in the network, thus enabling the method according to the invention. Advantageously, all radars in a radar network are each equipped with or connected to such a radar simulation unit.The invention is also directed to a radar with such a radar simulation unit and to a radar network with several radars, each with a radar simulation unit.

[0039] The invention further relates to a radar network with at least one radar simulation system as described above. The radar network can include a first and a second radar for tracking a moving object. To achieve high tracking reliability, the radar network can include a simulator for simulating the tracking of an object by the first radar along a motion path determined by a second radar, including determining the tracking quality of the simulated tracking. Furthermore, the radar network can include a predictor for predicting a future motion path of the object from tracking data of the second radar and a simulator for simulating the tracking of the object along the future motion path and for determining the tracking quality of the simulated future tracking.

[0040] To enable the transfer of tracking data between different radars in the radar network, it is advantageous for several radars in the network to each be equipped with a simulator and, in particular, a predictor, as well as a converter for converting the tracking data from an actively tracking radar to generate the prediction. The tracking data transfer can be performed by a transfer unit within the radar network. This transfer unit can be a radar simulation unit or another computer-based unit.

[0041] The preceding description of advantageous embodiments of the invention contains numerous features, some of which are summarized in several dependent claims. However, it is advantageous to consider these features individually and combine them into meaningful further combinations, particularly in the case of cross-references between claims, so that a single feature of a dependent claim can be combined with one, several, or all features of another dependent claim. Furthermore, these features can be combined with the inventive method as well as with the inventive apparatus according to the independent claims. Thus, method features can also be considered as properties of the corresponding apparatus unit, and functional apparatus features can also be considered as corresponding method features.

[0042] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings. The exemplary embodiments serve to illustrate the invention and do not limit it to the combination of features specified therein, including functional features. Furthermore, suitable features of each exemplary embodiment can also be considered explicitly in isolation, removed from one exemplary embodiment, incorporated into another exemplary embodiment to supplement it, and / or combined with any of the claims.

[0043] They show:

[0044] FIG 1 shows a radar network with multiple radars and a tracked flying object.

[0045] FIG 2 networked radar simulation systems of the radars of the radar network,

[0046] FIG 3 shows a flowchart of a handover of tracking of the flying object from one radar to another and

[0047] FIG 4 shows a flowchart of a future handover of tracking of the flying object from one radar to another.

[0048] FIG. 1 shows a radar network 2 with four radars 4a, 4b, 4c, 4d from different manufacturers, distributed across a landscape. An object 6 flies over the landscape and is actively tracked by radar 4a. Radar 4a transmits radar radiation to the object e and receives reflected radar radiation, as indicated by the double arrow in FIG. 1. From the received radar signal, radar 4a calculates a radar track of the object 6, which is referred to here as path 8a. Radar 4a transmits tracking data characterizing path 8a to the radar network 2. This data is received by the other radars 4. In the following, where no reference letter is given, reference is made to all units with the same reference numeral or to one or more units as specified in the text.

[0049] Each radar 4 contains or is connected to a radar simulation system 10a, 10b, 10c, 10d. The radar simulation systems 10a, 10b, 10c, 10d of radar network 2 are shown schematically in FIG. 2. The radar simulation systems 10 are each connected to or part of their respective radar 4. Each radar simulation system 10 is, for example, plugged into a data interface of its radar 4 or wirelessly connected to it. A radar simulation system 10 can be a mobile device, such as a laptop, that is connected to its radar 4, which also functions fully independently. The radars 4 of radar network 2 are part of the military systems of various countries and use different data standards. Radar network 2 is a Link 16 network with the corresponding communication standards. In addition to the four radars 4 shown, other radars may be present in radar network 2.These may or may not be equipped with a radar simulation system 10.

[0050] The radar simulation systems 10 each comprise a communication unit 12, which are interconnected via a communication network 14. Furthermore, each radar simulation system 10 includes a converter 16, a predictor 18, a simulator 20, and a quality unit 22. The communication units 12 serve to communicate with other radar simulation systems 10 of the radar network 2 and can each be part of their radar simulation system 10 or, outside their radar simulation system 10, they can be part of their radar 4, so that the radar 4 and its radar simulation system 10 each use the same communication unit 12. The converters 16 are each configured to convert the incoming tracking data into a format that the radar simulation system 10 can process and to convert the data determined by the radar simulation system 10 into a uniform network format before transmission.

[0051] The predictors 18 are configured to predict, i.e., predetermine, a future movement path 8b of the object 6 from tracking data received from radar 4a or another actively tracking radar 4. The predictors 18 are identical, so they predict an identical movement path 8b from the same tracking data. The simulators 20 are configured to simulate the tracking of the object 6 along movement path 8a or 8b by their respective radar 4s, using data from the flown movement path 8a and / or the predicted movement path 8b. The simulation shows how the respective radar 4 could track the object 6 along the movement path 8a or 8b if the radar 4 were to do so actively, or possibly passively if the radar 4's visibility of the object 6 were sufficient, for example, through the irradiation of the object 6 by one or more other radar emitters or an active radar of the object 6 itself.

[0052] From the simulation, the quality units 22 each determine a tracking quality for the simulated tracking of their radar 4. The tracking quality indicates the quality with which the respective radar 4 would track the object 6 along the movement path 8a, 8b if it were to do so in reality. The tracking quality specifies, for example, the accuracy and / or reliability of the tracking of the object 6 by the respective radar 4. The converter 16, the predictor 18, the simulator 20, and the quality unit 22 can each be separate hardware modules. It is also possible for two or more of these units to be combined into one. For example, a quality unit 22 can be part of its simulator 20, and / or the predictor 18 and the simulator 20 can be combined into a single unit.

[0053] In addition to their radar simulation system 10, the radars 4 each contain a radar antenna 24 and, optionally, a communication unit, which may be present in addition to the communication unit 12. A tracking unit 26 calculates the tracking data that characterizes the movement path 8a flown by the object 6.

[0054] FIG. 3 shows a flowchart of a procedure for determining the quality of tracking of a moving object 6 by one of the radars 4 of the radar network 2, for example, radar 4a. After a start 30 of the procedure, radar 4a tracks the object 6 and obtains tracking data from the tracking. Both of these actions can occur in step 32. The tracking 32 is usually active, with radar 4a actively illuminating the object 6. The other radars 4 of the radar network 2 can remain passive, i.e., without actively emitting radar radiation. Radar 4a can optionally transmit the tracking data to the communication network 14, making it available to every radar 4 of the radar network 2. In FIG. 3, radar 4a is represented as S1, as a general sensor 1, since any of the radars 4 could perform these procedure steps.The communication network 14 is symbolized by N and one of the other radars 4 of the radar network 2 with the general designation S2, sensor 2, since each of the other radars 4 could perform its procedural steps.

[0055] The tracking data that the actively tracking radar 4a feeds into radar network 2 can include a tracking quality 32. Tracking quality indicates the degree to which radar 4a can track object 6. Tracking quality can include the accuracy with which the location of object 6 was determined over time, such as the accuracy of determining the movement path 8a, the sampling frequency of the movement path 8a, and / or the reliability with which the location or movement path 8a was determined.Furthermore, the actively tracking radar 4a can transmit a class-specific object model to the other radars 4, including data on the type of object 6, such as whether it is an aircraft, rotorcraft, unmanned aerial vehicle, or rocket-powered aircraft, possibly along with the object 6's technical flight characteristics, i.e., acceleration, speed, and / or maneuverability. In addition to the object 6's technical characteristics, the class-specific object model can also transmit possible maneuvers or maneuver patterns, which may result from the object 6's technical characteristics, past maneuvers, and / or current movement situation. Maneuver patterns can include expected maneuvers in given situations. The class-specific object model can also contain maneuver probabilities.One or more other radars 4 of the radar network 2, for example, radar 4b from FIG. 1, receive the tracking data and convert this data into system-compliant data using their converter 16, so that this data is available to radar 4b or its radar simulation system 10b for internal processing. The conversion of the tracking data is shown in step 34. Using the tracking data generated by radar 4a, radar 4b performs a simulation of tracking the object 6 in step 36. This simulation 36 expediently uses radar properties of the radar 4b for which the simulation 36 is performed. The radar properties include technical capabilities of radar 4b, visibility properties of the object 6, and / or environmental properties of radar 4b.The technical capabilities of radar 4b can include the frequency channels used and / or configurations employed, such as a selected operating mode, the transmission power, and / or the direction of the main beam adapted to the terrain. A defect in radar 4b can also be taken into account. The technical capabilities can also include statistical characteristics of radar 4b, such as noise behavior and / or beam shape. The visibility characteristics of object 6 include, in particular, the direction-dependent retroreflectivity of object 6 in the direction towards radar 4b. Irradiation power and source can also be considered. The irradiation power can be zero if radar 4b is only passively tracking object 6, or it can be determined by the transmission power of radar 4b per spatial segment. The transmission power of one or more additional radars 4 that actively illuminate the object can also be considered.The environmental characteristics of radar 4b can include atmospheric attenuation, landscape features between radar 4b and object 6 and / or clutter effects.

[0056] The radar simulation system 10b, for example, takes into account the position and orientation of object 6 relative to radar 4b and models the statistical properties of radar 4b. Furthermore, processing can be performed using the current radar configuration and the set frequencies. Clutter effects, such as reflections or scattering from clouds, can also be considered as statistical disturbances. To account for these disturbances, the clutter can be extracted by the radar simulation system 10b from a clutter map, which was previously determined actively by radar 4b or by another unit. To determine whether and when a line of sight exists between radar 4b and object 6, the radar simulation system 10b can have a digital terrain model and know the position of its radar 4b in the terrain.Additionally, the first Fresnel zone of radar 4b, taking into account the positions of radar 4b and object 6, can be included in the calculation of the tracking quality.

[0057] The simulation results of radar simulation system 10b are output in the same format as the tracking data that active radar 4a sends to radar network 2. For example, the simulation results of radar simulation system 10b are treated like those of a Local SIM Track, or alternatively as Local Track Data with the simulation indicator flag enabled, as used, for example, in a J3.2 message.

[0058] The simulation of the tracking of object 6 by radar 4b indicates the tracking quality with which radar 4b could track object 6 if it were to do so in reality. The tracking quality can have identical quality parameters to the actual tracking quality reported by the actively tracking radar 4a. This facilitates a comparison of the tracking qualities. This quality comparison is performed in step 38. If this comparison shows that the actual tracking quality of the active radar 4a is higher than the simulated tracking quality of radar 4b for the same area of ​​the movement path 8a, the procedure returns to step 34, and the conversion 34 and simulation 36 are performed again with updated tracking data from radar 4a.However, if this comparison shows that the simulated tracking quality of radar 4b is higher than the actual tracking quality of radar 4a, then a transfer of the actual tracking from radar 4a to the still passive radar 4b can be planned. This transfer is only a planned transfer and not an actual transfer 44, which will take place later.

[0059] Before a real or actual handover 44, the accuracy of the simulation is checked by activating radar 4b in step 40 and illuminating object 6 with it. Both radars 4a and 4b now actively track object 6 and determine their tracking quality. These tracking qualities are compared in step 42. If the actual tracking quality of the now also active radar 4b is higher than the actual tracking quality of radar 4a, the handover 44 of tracking object 6 from radar 4a to radar 4b takes place. Radar 4b continues tracking object 6 in step 44 and becomes sensor S1. Radar 4a, on the other hand, is deactivated in step 46, thus ending its illumination of object 6, and becomes sensor S2. With these roles reversed, the tracking of object 6 continues in step 30.However, if the actual tracking quality of the now also active radar 4b is lower than the actual tracking quality of radar 4a, the intended transfer of tracking of object 6 from radar 4a to radar 4b does not take place. Radar 4b is deactivated again in step 48, and the process returns to receiving the current tracking data and data conversion 34. Radar 4a continues tracking object 6 in step 32 and remains sensor S1. Radar 4b remains sensor S2, and the process continues unchanged.

[0060] A real-world handover cannot depend solely on comparing tracking capabilities. The type of radar 4 handing over and, more importantly, receiving radar 4 can also be taken into account, particularly a protection factor that indicates how well a radar needs to be shielded from detection. This is especially relevant when handing over to a fire control radar or a launcher radar, if such a unit needs protection. The more valuable or critical a radar 4 is in a given situation, the higher the protection factor can be set. This can be considered during an automated handover, for example, by incorporating the protection factor into comparisons 38 and / or 42, so that the decision depends on both tracking capabilities and the protection factor.In the case of a manual decision, for example by a fire control center, the protection factor can be automatically presented to the decision-maker, or the decision-maker can take the protection factor into account on their own.

[0061] The handover 44 of the tracking information can be automatically agreed upon between the two participating radars 4. If, in addition to the quality comparison 38, 42, further factors need to be considered, the handover 44 should be carried out by a central point in the radar network 2, to which all radars 4 of the radar network 2 send their tracking quality data and / or the handover 44 should be carried out manually.

[0062] In the basic version of the procedure described so far, object 6 is illuminated only by the actively tracking radar 4a, whereby object 6 is only briefly illuminated by both participating radars 4a and 4b during a scheduled handover for verification. This protects the radars 4 of radar network 2 from detection.

[0063] Simulation 36 provides the passive radar 4b with the current location of object 6. Therefore, when radar 4b is activated for a planned handover, it is sufficient to illuminate only the path segment of the movement path 8a required for tracking. This also reduces the risk of detection.

[0064] As described previously for radar 4b, the other radars 4c and 4d of radar network 2 also proceed in the same way, so that, despite the passive radars 4b-d, the network knows which of the radars 4 can track object 6 with the highest quality. Each of the radars 4 can transmit its quality data to radar network 2, allowing a decision to be made based on this data as to which radar 4 has the best tracking quality, and the handover can be scheduled based on this comparison. The data transmitted by the radars 4 to radar network 2 can also be used as a heartbeat for the respective radars 4 within radar network 2. The availability of the quality data indicates that the respective radar 4 is operational and functioning as intended.

[0065] FIG. 4 shows a flowchart of another transfer procedure, which can be used to plan future transfers. The following description is essentially limited to the differences from the embodiment shown in FIG. 3, to which reference is made with regard to unchanged features and functions. To avoid repeating previously described details, all features of the preceding embodiment are adopted without being described again, unless features are specifically described as differences from the preceding embodiment.

[0066] In contrast to the previous procedure, the active sensor S1, for example, radar 4a, uses the tracking data in step 50 to perform a prediction of the future motion path 8b of object 6 over a prediction period. This prediction 50 is executed by predictor 18 of radar 4a and can include a reference track of object 6 containing its future positions, directions, and velocities as a function of time. Through extrapolation, prediction 50 can create a continuous motion path 8b of object 6 from individual calculation points. Furthermore, prediction 50 can include the orientation of object 6 in space and a direction-dependent radar cross section (RCS). Prediction 50 uses data on the past motion path 8a and, expediently, also the class-specific object model.Since radar 4a, like all other radars 4 of the radar network 2, contains a radar simulation system 10a, the prediction 50 can be performed by this radar simulation system 10a. Radar 4a can optionally transmit the data from this prediction 50 to the communication network 14, making it available to every radar 4 of the radar network 2. This optionality—that is, whether radar 4a transmits only the tracking data or both the tracking and prediction data to the communication network 14—is illustrated by dashed lines in FIG. 4.

[0067] If sensor S2 of radar network 2, for example radar 4b, receives only the tracking data—including the tracking quality—the radar simulation system 10b performs a prediction 52 after conversion 34, i.e., it creates the prediction 52 of the future movement path 8b from the tracking data as described above. If the prediction data is also or only received, prediction 52 by radar simulation system 10b can be omitted. Also in step 52, the received prediction is converted and can be processed directly. Prediction 50, 52 can therefore be generated by the first radar 4b (prediction 52) and / or by the second radar 4a (prediction 50). Setting the prediction 50 into the radar network 2 by the actively tracking radar 4a has the advantage that all other radars 4 of the radar network 2 have the identical prediction, which they can use to create a simulation 36.Alternatively or additionally, the prediction 52 of the future trajectory 8b can be generated separately by the additional radar 4b and / or the other radars 4 of the radar network 2. This is advantageous if the communication bandwidth in the communication network 14 is low at a critical point, e.g., in the connection from radar 4a to the communication network 14. A further advantage lies in concealing the prediction 52 to prevent the object 6 from determining and deliberately circumventing it.

[0068] Using the prediction generated by radar 4a in step 50 or the prediction generated by radar 4b in step 52, radar 4b performs a simulation of the future tracking of object 6 in step 36. This simulation 36 can be performed as described above, except that the data basis is not the actual tracking data, but the prediction data. Therefore, the simulation does not depict the tracking of object 6 along the flown path 8a, but rather along the future path 8b. This simulation can also be performed by the actively tracking radar 4a in step 54.

[0069] In comparison step 38, the tracking qualities derived from the simulation are compared. This can be done not only for a current point in time during the tracking 32 of object 6, but also for a future period. If this comparison 38 shows that the simulated tracking quality of the active radar 4a is higher for all points in time within the prediction period than the simulated tracking quality of radar 4b at the same points in time, the procedure returns to step 34 if only the tracking data is available, or to step 52 if the prediction 52 is available. However, if this comparison shows that the simulated tracking quality of radar 4b is higher than the simulated tracking quality of radar 4a from a certain point in time onward, a transfer of the actual tracking from radar 4a to the still passive radar 4b can be scheduled for that point in time.In this procedure as well, the accuracy of the simulation is checked in step 42 before an actual handover 44. For this purpose, the intended handover time can be awaited, and radar 4b can be activated within a predetermined time interval around the intended handover time in step 40. Now, both real tracking qualities can be compared 42, and the procedure can be carried out as described above. Another possibility is to compare the simulated tracking quality with the real tracking quality of the same radar 4b. The active radar 4a can perform this during active tracking 32. The passive radar 4b can only perform this after its activation in step 40, whereby simultaneous illumination of the object 6 by both radars 4a and 4b is not necessary if the simulation 54 of radar 4a corresponds sufficiently well with the real tracking.

[0070] If the actual tracking quality of the now active radar 4b is higher than that of radar 4a, the tracking of object 6 is transferred from radar 4a to radar 4b in step 44. Radar 4b continues tracking object 6 in step 44 and becomes sensor S1. Radar 4a, on the other hand, is deactivated in step 46, or may have already been deactivated, and becomes sensor S2. With these roles reversed, the tracking of object 6 continues in step 30. However, if the actual tracking quality of the now active radar 4b is lower than that of radar 4a, the intended transfer of tracking of object 6 from radar 4a to radar 4b does not take place. Radar 4b is deactivated again in step 48, and the process returns to step 34. Radar 4a continues tracking object 6 in step 32 and remains sensor S1. Radar 4b remains sensor S2; the procedure continues unchanged.

[0071] Simulation 36 of the tracking along the predicted motion path 8b has the advantage that the handover can be planned in advance without any tracking gaps. A further advantage is that the simultaneous illumination of object 6 by several radars 4 can be simulated without having to activate these radars 4. Therefore, the optimal illumination can be selected in advance and object 6 illuminated accordingly. A significant advantage is also that future tracking gaps can be identified. This is illustrated in FIG. 1 using a predicted future motion path 8b as an example. Radar 4a is actively tracking, and the simulation, based on prediction, shows that at time ti, radar 4b will have the best tracking quality.At a short time t2, however, object 6 will be behind a cloud and therefore difficult to track for radar 4b, whereas radar 4a will still have a clear view of object 6. In this scenario, it is advantageous not to perform the handover from radar 4a to radar 4b and to bridge the short period between h and t2 by maintaining sufficient tracking with radar 4a. After exiting the cloud, object 6 is best tracked by radar 4c. However, radar 4c's view of object 6 is soon obstructed by a mountain, as indicated by the dotted line in FIG. 1. Radar 4d, on the other hand, has a sufficiently good view of object 6 from time ta onwards. The handover from radar 4a to radar 4d is planned for time ta, checked at or after time ta, and implemented immediately thereafter.Radars 4b and 4c remain inactive at all times, although their tracking quality is briefly the best.

[0072] Reference symbol list

[0073] 2 Radar network

[0074] 4a-d Radar

[0075] 6 objects

[0076] 8a, b Movement path

[0077] 10a-d radar simulation system

[0078] 12 Communication unit

[0079] 14 Communication network

[0080] 16 converters

[0081] 18 predictor

[0082] 20 Simulator

[0083] 22 Quality Unit

[0084] 24 radar antenna

[0085] 26 tracking unit

[0086] 30 Start

[0087] 32 Pursuit

[0088] 34 Convert

[0089] 36 Simulation and Quality Assessment

[0090] 38 Quality comparison

[0091] 40 Activation

[0092] 42 Quality comparison

[0093] 44 Handover of the pursuit

[0094] 46 Deactivation

[0095] 48 Deactivation

[0096] 50 Prediction

[0097] 52 Prediction / Conversion

[0098] 54 Simulation and Quality Assessment

[0099] N Communication network

[0100] 51 Sensor 1

[0101] 52 Sensor 2 ti,2,3 Time points

Claims

1. Patent claims 1. Method for determining the quality of a tracking of a moving object (6) by a first radar (4b), wherein a motion path (8a, 8b) of the object (6) is created from tracking data obtained by a further radar (4a) from a tracking (32) of the object (6), and a radar simulation system (10b) creates a simulation (36) of a tracking of the object (6) carried out by the first radar (4b) including a tracking quality of the simulated tracking based on data of the motion path (8a, 8b).

2. Method according to claim 1, characterized in that of the two radars (4a, 4b) only the radar (4a) that generates the real tracking data (32) actively illuminates the object (6).

3. Method according to claim 1 or 2, characterized in that the tracking quality of the simulated tracking (36) of the first radar (4b) is compared with a real tracking quality of the tracking (32) of the further radar (4a) (38) and based on this comparison it is decided which of the two radars (4a, 4b) continues the tracking (32) of the object (6).

4. Method according to one of the preceding claims, characterized in that a prediction (50, 52) of a future movement path (8b) of the object (6) is created from the tracking data obtained by the further radar (4a) from the tracking (32) of the object (6) and the radar simulation system (10b) creates a simulation (36) of a future tracking of the object (6) carried out by the first radar (4b) including a tracking quality of the simulated tracking on the basis of data of the future movement path (8b) (36).

5. Method according to claim 4, dad u rch ge nzeich net that the prediction (50, 52) includes: technical properties of the object (6) and resulting possible maneuvers including their probability and / or past maneuvers and resulting maneuvers including their probability.

6. Method according to one of the preceding claims, characterized by the fact that the first radar (4b) upon activation (40) directs its radar beam only to the current and a predetermined near future location of the object (6) in the predicted motion path (8b).

7. Method according to one of the preceding claims, characterized by the fact that a future time (ts) of a handover of the tracking of the object (6) from the further to the first radar (4b) is determined on the basis of the tracking quality and the tracking of the object (6) is handed over to the first radar (4b) depending on this time (ts) (44).

8. Method according to one of the preceding claims, characterized by the fact that the determination (36) of the tracking quality includes technical characteristics of the first radar (4b).

9. Method according to one of the preceding claims, characterized by the fact that the determination (36) of the tracking quality includes the visibility of the object (6) by the first radar (4b).

10. Method according to one of the preceding claims, characterized by the fact that the determination (36) of the tracking quality includes landscape features between the first radar (4b) and the object (6) and / or clutter effects.

11. Method according to any of the preceding claims, characterized in that the simulation (36) includes a passive real tracking of the object (6) by the first radar (4b).

12. Method according to one of the preceding claims, characterized in that the tracking quality includes a minimum quality and / or an average value in a predefined tracking section.

13. Method according to one of the preceding claims, characterized in that the first radar (4b) feeds tracking quality data into a radar network (2) and this data is used as the heartbeat of the first radar (4b).

14. Radar simulation system (10b) for connecting to a first radar (4b), characterized by a simulator (20) for simulating (36) the tracking (36) of an object (6) by the first radar (4b) on a motion path (8a, 8b) determined by a further radar (4a) including the determination of a tracking quality of the simulated tracking.

15. Radar simulation system (10b) according to claim 14, characterized by a predictor (18) for predicting (52) a future movement path (8b) of the object (6) from tracking data of the further radar (4a), wherein the simulator (20) is prepared to simulate (36) the tracking of the object (6) by the first radar (4b) on the future movement path (8b) and to determine a tracking quality of the simulated future tracking.

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