A radar track pairing method and system in an interference environment

Abstract

The present application relates to the field of radar, the present application relates to a kind of radar track pairing method and system under the interference environment, the method in it includes: obtaining the multiple detection tracks of radar output and the real track of each real battle situation target, and the real track corresponding to each detection track is determined respectively to obtain pairing result, wherein determining the real track corresponding to certain detection track includes: selecting continuous multiple track points from detection track as to-be-matched track point;The track point in the real track of real battle situation target is interpolated to obtain the to-be-matched track point corresponding to each to-be-matched track point;The positioning error between each real battle situation target's to-be-matched track point and corresponding to-be-matched track point is calculated respectively;Real track corresponding to detection track and detection target are identified.The method of the present application can effectively solve the technical problems that time asynchronization exists when radar track is paired and pairing is prone to error in complex environment.

Description

Technical Field

[0001] This invention relates to the field of radar. More specifically, this invention relates to a radar track pairing method and system under jamming conditions. Background Technology

[0002] In the fields of modern radar data processing and electronic warfare, radar systems need to continuously detect and track multiple targets in the airspace. To objectively evaluate the radar's detection performance and anti-jamming effectiveness, high-precision reference equipment (such as optical measuring equipment or high-precision GPS measurement systems) is typically used to record the actual trajectories of targets in real combat situations. Subsequently, the system needs to pair the detected tracks output by the radar with the actual trajectories (i.e., data association) to determine which real target a particular track acquired by the radar belongs to.

[0003] However, existing radar track pairing technologies mainly face the following technical problems: First, multi-source data exhibits asynchronicity in the temporal dimension. The radar's scanning cycle, data transmission delay, and the sampling frequency of the reference equipment recording the actual trajectory are often inconsistent, making it difficult for the detected track data points and the actual trajectory data points to align naturally in terms of timestamps. If spatial distance is forcibly calculated directly between coordinate data at different times, it will introduce significant calculation errors due to time deviations, leading to subsequent pairing failures.

[0004] Second, data ambiguity is severe in complex electromagnetic environments. When facing complex combat situations such as dense decoys, highly dynamic target maneuvers, and electromagnetic interference (e.g., enemy-released towed jamming), radar detection images generate a large amount of clutter and accompanying false tracks. Existing pairing technologies typically rely on a single distance threshold for judgment. When multiple targets are densely intersecting or false tracks are approaching, "mispairing" or "misassociation" is highly likely to occur, failing to accurately assign the detection track uniquely to the correct real target. This results in subsequent radar effectiveness assessments and jamming status assessments lacking an accurate data foundation. Summary of the Invention

[0005] To address the technical problems of pairing failure and mispairing in existing radar track pairing technologies, this invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides a radar track pairing method under interference conditions, comprising: acquiring multiple detection tracks output by the radar and the actual trajectories of various real combat targets, determining the actual trajectory corresponding to each detection track to obtain a pairing result, and sending the pairing result to a smart terminal for display, wherein determining the actual trajectory corresponding to a certain detection track includes: Select multiple consecutive track points from the detected track as track points to be matched; Interpolation is performed on the trajectory points in the real trajectory of the real combat target to obtain the trajectory points to be matched corresponding to each trajectory point to be matched; the trajectory points to be matched corresponding to the trajectory points to be matched refer to the trajectory points to be matched at the same time as the trajectory points to be matched. Calculate the positioning error between the trajectory point to be matched and the corresponding flight path point for each real combat target; If the positioning error of a target trajectory point to be matched is less than the positioning error of other targets trajectory points to be matched, and the positioning error of each target trajectory point to be matched is less than the first positioning error threshold, then the true trajectory of the target trajectory is determined to be the true trajectory corresponding to the probe track, and the target trajectory is determined to be the probe target corresponding to the probe track.

[0007] Preferably, the interpolation process performed on the trajectory points in the actual trajectory of the real combat target to obtain the trajectory points to be matched corresponding to each trajectory point to be matched includes: Obtain the first timestamp of each track point in the probe track; The first timestamp is determined as the registration reference time; Based on the registration reference time, historical trajectory points and future trajectory points adjacent to the registration reference time are selected from the real trajectory; By combining the historical trajectory points, the future trajectory points, and the registration reference time, interpolation calculations are performed to obtain the spatial coordinates of the trajectory points at the registration reference time. The coordinate points corresponding to the spatial coordinates of the trajectory points at the registration reference time are the trajectory points to be matched corresponding to the track points to be matched.

[0008] Preferably, linear interpolation is used when performing interpolation calculations by combining the historical trajectory points, the future trajectory points, and the registration reference time.

[0009] Preferably, the expression for calculating the x-axis coordinates of the trajectory points at the registration reference time is: ; The expression for calculating the y-axis coordinate of the trajectory point at the registration reference time is as follows:

[0010] The expression for calculating the z-axis coordinate of the trajectory point at the registration reference time is as follows: ; Of the above formulas, , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory points at the registration reference time, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the historical trajectory points, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the future trajectory point, respectively. , These represent the corresponding times of the historical trajectory points and the future trajectory points, respectively. This indicates the registration reference time.

[0011] Preferably, the positioning error between the trajectory point to be matched and the corresponding waypoint to be matched The calculation expression is: ; In the formula, , , These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory point to be matched, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the track point to be matched, respectively.

[0012] Preferably, the method further includes: calculating the effective detection time period of the corresponding real combat target based on the real trajectory corresponding to the detected track, wherein the positioning error between each track point and the corresponding trajectory point within the effective detection time period is less than the first positioning error threshold, and the time interval between adjacent track points is less than the time interval threshold, and the positioning error between the first track point and the corresponding trajectory point is greater than the first positioning error threshold, and the positioning error between the second track point and the corresponding trajectory point is greater than the first positioning error threshold, wherein the first track point refers to the track point located in the left neighboring region of the effective detection time period and adjacent to the left endpoint of the effective detection time period, and the second track point refers to the track point located in the right neighboring region of the effective detection time period and adjacent to the right endpoint of the effective detection time period.

[0013] Preferably, it also includes: determining the number of real targets detected by the radar based on the effective detection time period of each real combat target.

[0014] Preferably, determining the number of real targets detected by the radar based on the effective detection time period of each real combat target includes: determining whether each real combat target was actually detected, and counting the number of real combat targets that were actually detected to obtain the number of real combat targets actually detected. Specifically, determining whether a particular real combat target was actually detected includes: The effective detection time period of the real combat target is compared with the effective detection time threshold; If the duration of the effective detection period is greater than the effective detection duration threshold, then the real combat target is determined to have been detected.

[0015] Preferably, it also includes determining whether the towing interference against the actual combat target was successful, including: Calculate the positioning error between each trajectory point to be matched and the corresponding flight path point of the real combat target; Calculate the root mean square value of each positioning error of the real combat target, and compare the root mean square value with the second positioning error threshold. If the root mean square value is greater than the second positioning error threshold, the dragging interference against the real combat target is determined to be successful.

[0016] In a second aspect, the present invention provides a radar track pairing system under jamming conditions, including a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the radar track pairing method under jamming conditions of the present invention is implemented.

[0017] The beneficial effects of this invention are as follows: The method addresses the radar track pairing problem in jammed environments by interpolating real track points to ensure they are at the same time as the track points to be matched. This effectively eliminates calculation errors caused by asynchronous time processing of multi-source data, achieving precise time registration. More importantly, during spatial pairing judgment, it requires not only that the positioning errors corresponding to each track point to be matched for the real combat target are less than a first positioning error threshold (absolute error threshold), but also that this positioning error is less than the positioning errors corresponding to the track points to be matched for other real combat targets (relative exclusivity judgment). This dual rigorous judgment logic of "absolute threshold + relative comparison" successfully solves the data ambiguity problem in dense false targets and complex jamming environments, achieving high-precision unique track pairing. This directly solves the technical problems of asynchronous time processing and error-prone pairing in complex environments inherent in radar track pairing technology. Attached Figure Description

[0018] Figure 1 This is a schematic flowchart illustrating a radar track pairing method under interference conditions according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating trajectory points in a real trajectory according to an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating a radar track pairing system under interference conditions according to an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Example of radar track pairing method under jamming environment: like Figure 1 As shown, the radar track pairing method under interference environment of the present invention includes: acquiring multiple detection tracks output by the radar and the real trajectories of each real combat target, determining the real trajectory corresponding to each detection track to obtain a pairing result, and sending the pairing result to a smart terminal for display. Determining the real trajectory corresponding to a certain detection track includes: S101. Select multiple consecutive track points from the detected track as track points to be matched; S102. Obtain the trajectory points to be matched corresponding to each track point to be matched. Specifically, interpolate the trajectory points in the real trajectory of the real combat target to obtain the trajectory points to be matched corresponding to each track point to be matched. The trajectory points to be matched corresponding to each track point to be matched refer to the trajectory points to be matched at the same time as the track points to be matched. S103. Calculate the positioning error between the trajectory point to be matched and the corresponding flight path point of each real combat target. In this embodiment, the positioning error between the trajectory point to be matched and the corresponding waypoint to be matched is... The calculation expression is: ; In the formula, , , These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory point to be matched, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the track point to be matched, respectively.

[0022] The positioning error is calculated using the Euclidean distance formula in three-dimensional space. This method can most intuitively and objectively reflect the true geometric deviation between the waypoints to be matched and the trajectory points to be matched in three-dimensional physical space, providing reliable basic data for subsequent accurate pairing.

[0023] S104. Identify the real trajectory and detection target corresponding to the detection track, specifically: in response to the fact that the positioning error corresponding to the trajectory point to be matched for a certain real combat target is less than the positioning error corresponding to the trajectory point to be matched for other real combat targets, and the positioning error corresponding to each trajectory point to be matched for the real combat target is less than the first positioning error threshold, then the real trajectory of the real combat target is determined to be the real trajectory corresponding to the detection track, and the real combat target is determined to be the detection target corresponding to the detection track.

[0024] There are several ways to compare the positioning errors of the matching trajectory points of two real combat targets. One method is to compare the positioning errors of the matching trajectory points of the two real combat targets one by one. For example, suppose the matching trajectory points of real combat target A are arranged in chronological order as trajectory point Q, trajectory point W, and trajectory point E, and the matching trajectory points of real combat target B are arranged in chronological order as trajectory point R, trajectory point T, and trajectory point Y. The positioning error of trajectory point Q is smaller than that of trajectory point R, the positioning error of trajectory point W is smaller than that of trajectory point T, and the positioning error of trajectory point E is smaller than that of trajectory point Y. Then it is determined that the positioning error of the matching trajectory point of real combat target A is smaller than that of the matching trajectory point of real combat target B.

[0025] Another approach is to calculate the average positioning error of each trajectory point to be matched for the real combat target, and then compare the average positioning errors of the two real combat targets.

[0026] The positioning errors of the trajectory points to be matched for two real combat targets are compared one by one. If the positioning errors of each trajectory point to be matched for one of the real combat targets are... After determining the actual trajectory corresponding to each detection track, the radar's anti-jamming effectiveness can be evaluated based on the detection track and the corresponding actual trajectory.

[0027] This invention addresses the radar track pairing problem in jammed environments. By interpolating real track points to synchronize them with the track points to be matched, it effectively eliminates computational errors caused by asynchronous time processing of multi-source data, achieving precise time registration. More importantly, during spatial pairing judgment, it requires not only that the positioning errors corresponding to each track point to be matched for the real combat target be less than a first positioning error threshold (absolute error threshold), but also that this positioning error be less than the positioning errors corresponding to the track points to be matched for other real combat targets (relative exclusivity judgment). This dual rigorous judgment logic of "absolute threshold + relative comparison" successfully solves the data ambiguity problem in dense false targets and complex jamming environments, achieving high-precision unique track pairing. This directly solves the technical problems of asynchronous time processing and error-prone pairing in complex environments inherent in radar track pairing technology.

[0028] In one embodiment, the interpolation process performed on trajectory points in the actual trajectory of the real combat target to obtain the trajectory points to be matched corresponding to each track point to be matched includes: S201. Obtain the first timestamp of each track point in the probe track; S202. Determine the first timestamp as the registration reference time; S203. Based on the registration reference time, select historical trajectory points and future trajectory points adjacent to the registration reference time from the real trajectory; like Figure 2 As shown, assuming the trajectory points in the real trajectory include trajectory point A, trajectory point B, trajectory point C, trajectory point D, and trajectory point E, and the time corresponding to trajectory point A is earlier than the time corresponding to trajectory point B, the time corresponding to trajectory point B is earlier than the time corresponding to trajectory point C, the time corresponding to trajectory point C is earlier than the time corresponding to trajectory point D, and the time corresponding to trajectory point D is earlier than the time corresponding to trajectory point E, and the registration reference time is the time t between the time corresponding to trajectory point B and the time corresponding to trajectory point C, then the historical trajectory point and the future trajectory point adjacent to the registration reference time are trajectory point B and trajectory point C, respectively.

[0029] S204. By combining the historical trajectory points, the future trajectory points, and the registration reference time, interpolation calculation is performed to obtain the spatial coordinates of the trajectory points at the registration reference time. The coordinate points corresponding to the spatial coordinates of the trajectory points at the registration reference time are the trajectory points to be matched corresponding to the track points to be matched.

[0030] This embodiment clarifies the specific interpolation implementation path for time registration. By extracting the timestamp of the probe track as the registration reference time, and accurately locating adjacent historical and future trajectory points in the real trajectory, the interpolation calculation is limited to a very small temporal neighborhood. This greatly improves the accuracy of the interpolated coordinates, ensuring that the trajectory points to be matched can truly reflect the spatial position of the target at the moment of detection.

[0031] In this embodiment, linear interpolation is used when performing interpolation calculations by combining the historical trajectory points, the future trajectory points, and the registration reference time.

[0032] When the time interval between adjacent historical and future trajectory points is short, linear interpolation significantly reduces computational complexity while ensuring sufficient fitting accuracy, thus guaranteeing the real-time requirements of radar track data processing.

[0033] The expression for calculating the x-axis coordinate of the trajectory point at the registration reference time is as follows: ; The expression for calculating the y-axis coordinate of the trajectory point at the registration reference time is as follows:

[0034] The expression for calculating the z-axis coordinate of the trajectory point at the registration reference time is as follows:

[0035] Of the above formulas, , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory points at the registration reference time, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the historical trajectory points, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the future trajectory point, respectively. , These represent the corresponding times of the historical trajectory points and the future trajectory points, respectively. This indicates the registration reference time.

[0036] In one embodiment, the method further includes: calculating an effective detection time period for the corresponding real combat target based on the actual trajectory corresponding to the detected track, wherein the positioning error between each track point and the corresponding trajectory point within the effective detection time period is less than a first positioning error threshold, and the time interval between adjacent track points is less than the time interval threshold, and the positioning error between the first track point and the corresponding trajectory point is greater than the first positioning error threshold, and the positioning error between the second track point and the corresponding trajectory point is greater than the first positioning error threshold, wherein the first track point refers to a track point located in the left neighboring region of the effective detection time period and adjacent to the left endpoint of the effective detection time period, and the second track point refers to a track point located in the right neighboring region of the effective detection time period and adjacent to the right endpoint of the effective detection time period.

[0037] This embodiment introduces the parameter of "effective detection time period" and performs extremely rigorous mathematical definition of the neighborhood boundary conditions of its left and right endpoints (i.e., small and uninterrupted error within the segment, and large error at adjacent points outside the segment). This enables the system to automatically and accurately extract effective segments of continuous and effective target tracking from massive radar detection data, realizing the quantitative extraction of radar tracking stability.

[0038] In one embodiment, the method further includes: determining the number of real targets detected by the radar based on the effective detection time period of each real combat target.

[0039] In this embodiment, determining the number of real targets detected by the radar based on the effective detection time period of each real combat target includes: determining whether each real combat target was actually detected, and counting the number of real combat targets that were actually detected to obtain the number of real combat targets actually detected. Specifically, determining whether a particular real combat target was actually detected includes: S301. Compare the effective detection time period of the real combat target with the effective detection time threshold; S302. If the duration of the effective detection period is greater than the effective detection duration threshold, then the real combat target is determined to have been detected.

[0040] By comparing the duration of the effective detection period with an effective detection duration threshold, transient false pairings caused by accidental factors (such as instantaneous clutter) are filtered out. Only when the continuous tracking time is long enough is the target considered to have been truly detected, thus obtaining a high-confidence number of real targets detected by the radar, providing a reliable indicator for the macroscopic assessment of radar detection capabilities.

[0041] In one embodiment, the method further includes determining whether the towing interference against a real combat target was successful, including: S401. Calculate the positioning error between each trajectory point to be matched and the corresponding flight path point of the target in the real combat situation. S402. Calculate the root mean square value of each positioning error of the real combat target, and compare the root mean square value with the second positioning error threshold. S403. In response to the root mean square value being greater than the second positioning error threshold, it is determined that the dragging interference against the real combat target is successful.

[0042] This embodiment extends the results of track pairing to the field of electronic countermeasures effectiveness evaluation. By calculating the root mean square value of the positioning error of a continuous track, statistical characteristics are used to smooth out single-point random measurement noise. When the root mean square value is greater than a second positioning error threshold, the towed jamming is determined to be successful. This provides an objective criterion for quantitatively evaluating the effect of enemy electromagnetic interference and the anti-jamming capability of our radar.

[0043] Example of a radar track pairing system under jamming conditions: This invention also provides a radar track pairing system for use in jammed environments. For example... Figure 3 As shown, the radar track pairing system under interference environment includes a processor and a memory. The memory stores computer program instructions. When the computer program instructions are executed by the processor, a radar track pairing method under interference environment as described in the above embodiments is implemented.

[0044] The radar track pairing system under interference conditions also includes other components well known to those skilled in the art, such as communication buses and communication interfaces. Their settings and functions are known in the art and will not be described in detail here.

[0045] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A radar track pairing method under interference conditions, characterized in that, include: The system acquires multiple detection tracks output by the radar and the actual trajectories of various real combat targets, determines the actual trajectory corresponding to each detection track to obtain pairing results, and sends the pairing results to a smart terminal for display. Determining the actual trajectory corresponding to a specific detection track includes: Select multiple consecutive track points from the detected track as track points to be matched; Interpolation is performed on the trajectory points in the real trajectory of the real combat target to obtain the trajectory points to be matched corresponding to each trajectory point to be matched; the trajectory points to be matched corresponding to the trajectory points to be matched refer to the trajectory points to be matched at the same time as the trajectory points to be matched. Calculate the positioning error between the trajectory point to be matched and the corresponding flight path point for each real combat target; If the positioning error of a target trajectory point to be matched is less than the positioning error of other targets trajectory points to be matched, and the positioning error of each target trajectory point to be matched is less than the first positioning error threshold, then the true trajectory of the target trajectory is determined to be the true trajectory corresponding to the probe track, and the target trajectory is determined to be the probe target corresponding to the probe track.

2. The radar track pairing method under interference environment as described in claim 1, characterized in that, The process of interpolating trajectory points in the real trajectory of the actual combat target to obtain the trajectory points to be matched for each trajectory point to be matched includes: Obtain the first timestamp of each track point in the probe track; The first timestamp is determined as the registration reference time; Based on the registration reference time, historical trajectory points and future trajectory points adjacent to the registration reference time are selected from the real trajectory; By combining the historical trajectory points, the future trajectory points, and the registration reference time, interpolation calculations are performed to obtain the spatial coordinates of the trajectory points at the registration reference time. The coordinate points corresponding to the spatial coordinates of the trajectory points at the registration reference time are the trajectory points to be matched corresponding to the track points to be matched.

3. The radar track pairing method under interference environment as described in claim 2, characterized in that, When performing interpolation calculations by combining the historical trajectory points, the future trajectory points, and the registration reference time, a linear interpolation method is used.

4. The radar track pairing method under interference environment as described in claim 3, characterized in that, The expression for calculating the x-axis coordinate of the trajectory point at the registration reference time is as follows: ； The expression for calculating the y-axis coordinate of the trajectory point at the registration reference time is as follows: The expression for calculating the z-axis coordinate of the trajectory point at the registration reference time is as follows: ； Of the above formulas, , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory points at the registration reference time, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the historical trajectory points, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the future trajectory point, respectively. , These represent the corresponding times of the historical trajectory points and the future trajectory points, respectively. This indicates the registration reference time.

5. The radar track pairing method under interference environment as described in claim 1, characterized in that, The positioning error between the trajectory point to be matched and the corresponding waypoint to be matched The calculation expression is: ； In the formula, , , These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the trajectory point to be matched, respectively. , and These represent the x-axis coordinates, y-axis coordinates, and z-axis coordinates of the track point to be matched, respectively.

6. The radar track pairing method under interference environment as described in claim 1, characterized in that, Also includes: The effective detection time period for the corresponding real combat target is calculated based on the actual trajectory corresponding to the detected track. The positioning error between each track point and the corresponding trajectory point within the effective detection time period is less than the first positioning error threshold, and the time interval between adjacent track points is less than the time interval threshold. The positioning error between the first track point and the corresponding trajectory point is greater than the first positioning error threshold, and the positioning error between the second track point and the corresponding trajectory point is greater than the first positioning error threshold. The first track point refers to the track point located in the left neighboring region of the effective detection time period and adjacent to the left endpoint of the effective detection time period. The second track point refers to the track point located in the right neighboring region of the effective detection time period and adjacent to the right endpoint of the effective detection time period.

7. The radar track pairing method under interference environment as described in claim 6, characterized in that, Also includes: The number of real targets detected by the radar is determined based on the effective detection time period of each real combat target.

8. The radar track pairing method under interference environment as described in claim 7, characterized in that, Determining the number of real targets detected by the radar based on the effective detection time period of each real combat target includes: determining whether each real combat target was actually detected, and counting the number of real combat targets that were actually detected to obtain the number of real combat targets actually detected. Specifically, determining whether a particular real combat target was actually detected includes: The effective detection time period of the real combat target is compared with the effective detection time threshold; If the duration of the effective detection period is greater than the effective detection duration threshold, then the real combat target is determined to have been detected.

9. The radar track pairing method under interference environment as described in any one of claims 1 to 8, characterized in that, It also includes determining whether the dragging interference against actual combat targets was successful, including: Calculate the positioning error between each trajectory point to be matched and the corresponding flight path point of the real combat target; Calculate the root mean square value of each positioning error of the real combat target, and compare the root mean square value with the second positioning error threshold. If the root mean square value is greater than the second positioning error threshold, the dragging interference against the real combat target is determined to be successful.

10. A radar track pairing system under interference conditions, comprising a processor and a memory, wherein the memory stores computer program instructions, characterized in that, When the computer program instructions are executed by the processor, the radar track pairing method under interference environment as described in any one of claims 1 to 9 is implemented.

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