A target matching method and system based on Doppler linear relationship of double receiving stations

Abstract

The application discloses a target matching method and system based on a Doppler linear relationship of double receiving stations, and comprises the following steps: obtaining Doppler frequency shift measurements of a first receiving station and a second receiving station in a system comprising one transmitting station and at least two receiving stations; generating a candidate measurement pair of Doppler of the two receiving stations; constructing a two-dimensional Doppler point set on multiple observation times for a candidate target; performing straight line fitting on the point set to obtain a slope of the fitted straight line and a linearity evaluation index; determining a reasonable slope value range and a linearity threshold based on a target motion geometric relationship and a double receiving station geometric relationship; and determining that the Doppler measurements of the two receiving stations come from the same target when the fitted slope falls within the reasonable slope value range and the linearity evaluation index is satisfied. The application utilizes the linear characteristic of the double station Doppler in a two-dimensional space to perform matching determination, and effectively improves the accuracy and robustness of multi-station target matching.

Description

Technical Field

[0001] This invention relates to the field of radar signal processing and target information fusion technology, specifically to a target matching method and system based on the linear relationship of two-dimensional Doppler space between two receiving stations, applicable to target association and trajectory matching in multi-station radar, bistatic radar or passive radar networks. Background Technology

[0002] Single-frequency radar and some passive radars, due to their signal characteristics, cannot obtain target range measurements. Therefore, it is considered to use bistatic or multistatic passive radar measurements to locate targets. However, in multistatic information fusion, in order to obtain higher-dimensional information or higher target positioning accuracy, it is necessary to first solve the target matching problem between echo measurements from different receiving stations, that is, to determine whether the echo measurement on one receiving station and the measurement on another receiving station originate from the same physical target.

[0003] Common target matching and association methods in the prior art include:

[0004] 1. Nearest neighbor matching method based on spatial distance measurement;

[0005] 2. Joint Probabilistic Data Association (JPDA) Method Based on Statistical Models;

[0006] 3. Complex association methods based on multiple hypothesis tracking (MHT), etc.

[0007] The above methods generally suffer from the following problems:

[0008] 1. Lack of methods for target matching when location or distance information is missing.

[0009] 2. The matching method is greatly affected by orientation or distance. When the orientation or distance measurement error is large or even unmeasurable, the matching effect is very poor.

[0010] Therefore, it is necessary to propose a matching determination method that utilizes the two-dimensional spatial relationship characteristics of dual-receiving station Doppler, combining the target motion geometry with Doppler measurement characteristics to improve the accuracy and robustness of multi-station target matching. Summary of the Invention

[0011] The purpose of this invention is to overcome the problems of existing multi-station target matching methods being sensitive to measurement noise and having serious matching ambiguities in complex scenarios. This invention proposes a target matching method and system based on the linear relationship of the Doppler frequency shift of the target at the two receiving stations in two-dimensional space. By analyzing the approximate linear relationship of the Doppler frequency shift of the target at the two receiving stations in two-dimensional space and the range of slope changes, linearity criteria and slope criteria are constructed to achieve effective discrimination of whether candidate measurement pairs come from the same target, thereby improving the accuracy of multi-station target matching.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A target matching method based on the linear relationship of Doppler signals from two receiving stations includes the following steps:

[0014] (1) In a radar or passive receiving system containing one transmitting station and at least two receiving stations, the Doppler frequency shift measurements of the target echo signal by the first receiving station and the second receiving station are acquired, and the Doppler measurement sequence set of the first receiving station and the Doppler measurement sequence set of the second receiving station are formed respectively.

[0015] (2) Based on time, orientation, distance or other constraints, select candidate measurement sequence pairs from the first receiving station Doppler measurement set and the second receiving station Doppler measurement set;

[0016] (3) For a candidate target, collect its Doppler frequency shift at the first and second receiving stations at multiple observation times to form a two-dimensional Doppler point set;

[0017] (4) Perform linear fitting on the two-dimensional Doppler point set to obtain the slope and linearity evaluation index of the fitted line;

[0018] (5) Based on the geometric relationship of the target motion and the geometric relationship of the dual receiving station layout, the Doppler frequency shift relationship between the first receiving station and the second receiving station is theoretically analyzed to determine the reasonable range of slope values ​​and the linearity threshold.

[0019] (6) When the fitted slope falls within a reasonable range and the linearity evaluation index meets the decision threshold, it is determined that the Doppler measurements of the two receiving stations corresponding to the two-dimensional Doppler point set come from the same target; otherwise, it is determined that they are different targets or unreliable matching.

[0020] Furthermore, in step (4), the straight line fitting is performed using the least squares method, and the linearity evaluation index is the coefficient of determination of the fitted straight line. Or at least one of the mean square error.

[0021] Furthermore, the reasonable range of slope values ​​mentioned in step (5) is determined based on the geometric configuration of the dual receiving stations and the theoretical derivation and simulation analysis of the target heading angle.

[0022] A target matching system based on dual-receiving-station Doppler linear relationship is provided to implement the aforementioned target matching method based on dual-receiving-station Doppler linear relationship; the system includes:

[0023] The receiving station module is used to receive the echo signal of the signal transmitted by the transmitting station after it has been scattered by the target;

[0024] The Doppler extraction module is used to perform Doppler processing on the echo signal and extract the Doppler frequency shift measurements of the first and second receiving stations.

[0025] The candidate generation module is used to generate candidate measurement pairs from the Doppler measurement sets of the first and second receiving stations based on time, orientation, distance or other conditions.

[0026] The linear modeling module is used to construct a two-dimensional Doppler point set from the Doppler measurements of the two receiving stations of the candidate target at multiple observation times, and to perform linear fitting on the point set to obtain the fitting slope and linearity evaluation index.

[0027] The matching and determination module is used to perform matching and determination on the two-dimensional Doppler point set according to the preset reasonable value range of slope and linearity threshold. When the slope falls within the reasonable value range of slope and the linearity evaluation index meets the linearity threshold, the module outputs the determination result that the measurements of the two receiving stations are from the same target.

[0028] Furthermore, the matching determination module is also used to perform theoretical analysis on the Doppler frequency shift relationship between the first and second receiving stations based on the geometric configuration of the dual receiving stations and the target motion model, and to determine the reasonable range of slope values ​​and linearity threshold in an offline manner.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] 1. Introduce bistatic Doppler geometric constraints: By theoretically deriving the functional relationship between the Doppler frequency shifts of receiver station 1 and receiver station 2, the target motion geometry is directly combined with the measurement space structure, thereby improving the discriminative power of matching determination.

[0031] 2. Matching determination using two-dimensional Doppler linear features: By utilizing the linear distribution characteristics and slope variation range of the Doppler signals from the two receiving stations in two-dimensional space, the target motion information is implicitly encoded into the matching criteria, which can effectively distinguish between measurement combinations of "the same target" and "different targets".

[0032] 3. Good robustness: Under a certain amount of measurement noise and trajectory disturbance, the Doppler point set as a whole still maintains approximately linearity. The matching criterion based on linearity is not sensitive to single-point anomalies, thereby improving the stability of matching.

[0033] 4. Wide range of applications: It can be applied to various scenarios such as bistatic radar, distributed multistation radar, and passive radar network. It can also be combined with existing data association algorithms such as nearest neighbor, JPDA, and MHT as a pre-screening or auxiliary criterion. Attached Figure Description

[0034] Figure 1 This is a flowchart of the method of the present invention;

[0035] Figure 2 The slope of the two-dimensional Doppler relationship as an example varies with the included angle. Diagram illustrating the relationship of change;

[0036] Figure 3 The following is a simulation result of the dual-receiver station two-dimensional Doppler operation in the example embodiment;

[0037] Figure 4 The simulation results generated for this example;

[0038] Figure 5 The matching track results are shown in the example.

[0039] Figure 6 The example shows a statistical chart of track matching results. Detailed Implementation

[0040] The method and system of the present invention will be further described below with reference to the accompanying drawings and specific mathematical derivations. It should be understood that the following embodiments are only for illustrating the present invention and are not intended to limit the scope of protection of the present invention.

[0041] This embodiment follows the following... Figure 1 The flowchart shown is for estimating the slope range of the Doppler linear relationship between two receiving stations:

[0042] 1. Assume the system includes: a launching station Receiving Station 1 (First Receiving Station) — Receiving Station 2 (Second Receiving Station) — and individual moving targets ;set up , , These represent the distances between the transmitting station, receiving station 1, receiving station 2, and the target, respectively; assuming the target moves at a speed of... It moves at a constant velocity in a straight line, and its heading angle is... The carrier frequency of the transmitted signal is The speed of electromagnetic wave propagation is ;Target relative to receiving station The radial velocity component is denoted as The corresponding Doppler frequency shifts of the target at receiving station 1 and receiving station 2 are respectively , The Doppler frequency shift components of the target relative to receiving station 1 and receiving station 2 are respectively , The Doppler frequency shift component of the target relative to the launching station is .

[0043] 2. Basic formula for Doppler frequency shift:

[0044] The radial velocity of the target relative to the receiver is When the target is at that time, the Doppler frequency shift component relative to the receiver is:

[0045] ,

[0046] in, For the Doppler frequency shift component, For the transmission frequency, The relative radial velocity between the target and the receiver. It is the speed of light.

[0047] 3. Target velocity component relative to the receiving station:

[0048] Let the angle between the target's heading and the line of sight of receiving station 1 be . The angle between the line of sight to receiving station 2 and the line of sight to receiving station 2 is Then we have:

[0049] Radial velocity component relative to receiving station 1:

[0050] ,

[0051] Radial velocity component relative to receiving station 2:

[0052] ,

[0053] The corresponding Doppler frequency shift component is:

[0054] ,

[0055] ,

[0056] 4. Angle relationship between the two receiving stations:

[0057] Let the angle between the target and receiving station 1 and receiving station 2 be . Then it can be written as:

[0058] ,

[0059] Substituting the above relationships, we get:

[0060] ,

[0061] in:

[0062] ,

[0063] We can obtain:

[0064] ,

[0065] Let the angle between the target and receiving station 1 and the transmitting station be . Similarly, we can obtain:

[0066] ,

[0067] Combined again:

[0068] ,

[0069] ,

[0070] We can obtain:

[0071] ,

[0072] Considering over-the-horizon skywave detection, the receiving station is relatively far from the target (around 2000 km), while the target is relatively close at the transmitting station (around 200 km). Over a certain period, the uniform linear motion of the target causes an angle between the two stations. The angle between the target's heading and the line of sight of receiving station 1 is The change is very small, so it can be set as a constant value, and only the target motion with respect to the included angle needs to be considered. The impact.

[0073] Therefore, it can be simplified to:

[0074] ,

[0075] in:

[0076] ,

[0077] Based on the actual scenario, the angle between the two stations is set. The angle between the target's heading and the line of sight of receiving station 1 Simulation slope Depending on the angle The relationship of change is as follows Figure 2 As shown, the simulation results can be obtained when the angle When varying within most of the value range The slope changes relatively gently with the angle, approaching a certain constant value, and in Within the range, the slope changes drastically only at specific angles; outside this range...

[0078] Therefore, given the geometric structure and a certain speed constraint, Compared to It exhibits an approximately linear relationship in two-dimensional space, and the slope range in most cases can be estimated using the above formula. A matching threshold can be constructed by combining the linearity index and the range of values.

[0079] Let the location of receiving station 1 be (0km, 0km), the location of receiving station 2 be (2000km, 0km), the location of the transmitting station be (1000km, 1700km), the initial position of the target be (900km, 1750km), the initial velocity be 300m / s, and the heading angle be 30° (north-east). Calculate the corresponding Doppler velocities of the receiving stations using the bistatic Doppler formula, and draw the two-dimensional Doppler diagrams of the two receiving stations as shown below. Figure 3 As shown, it can be seen that the Doppler relationship between the two receiving stations is indeed approximately a straight line.

[0080] Example 2: Matching Determination Method Based on Two-Dimensional Doppler Linear Relationship

[0081] This embodiment provides a specific matching algorithm flow, the steps of which are as follows:

[0082] Step S1: Data Acquisition

[0083] Construct a radar or passive receiving system comprising one transmitting station and at least two receiving stations. The transmitting station transmits a signal, and receiving stations 1 and 2 synchronously receive the target echoes. Through Doppler processing or moving target detection, obtain a set of Doppler frequency shift measurements of multiple target echoes at each receiving station within the observation time slot.

[0084] Doppler measurement set at receiving station 1: ;

[0085] Doppler measurement set at receiving station 2: .

[0086] Step S2: Generation of candidate measurement pairs

[0087] Based on time synchronization information, rough orientation, or other conditions, the Doppler measurements from receiving station 1 and receiving station 2 are initially screened to generate a set of candidate measurement pairs:

[0088] ,

[0089] Each pair in this set may come from the same target.

[0090] Step S3: Construct a two-dimensional Doppler point set

[0091] For a given potential target trajectory, Doppler measurements at receiving station 1 and receiving station 2 are collected at multiple consecutive observation times to form a two-dimensional point set:

[0092] ,

[0093] Step S4: Linear Fitting and Linearity Evaluation

[0094] Pair set The linear model is fitted using the least squares method:

[0095] ,

[0096] Obtain the fitted slope and intercept And linearity evaluation metrics, such as: sum of squared residuals; coefficient of determination. Normalized mean square error, etc.

[0097] Step S5: Determining the slope and linearity thresholds

[0098] Based on theoretical derivation and simulation analysis, the slope determination interval is selected. ,For example:

[0099] ,

[0100] And set a linearity threshold (For example, for) (lower limit).

[0101] The judgment rule can be set as follows:

[0102] when And the linearity index satisfies At that time, it is considered that the point set The corresponding Doppler measurements come from the same target, so the match is valid;

[0103] Otherwise, it is determined to be a different target or a mismatch.

[0104] Step S6: Output the matching results

[0105] Repeat steps S3-S5 for all candidate measurement pairs or trajectory sets, and output the matching result.

[0106] Based on the above method, the coefficient of determination is set as follows: The slope determination interval is Using simulated data to replace the aircraft's actual flight data, Doppler information of the aircraft target relative to receiving station 1 and receiving station 2 was obtained through simulation. The generated Doppler measurement set was then used for the matching decision, resulting in a total of 9 tracks. After the decision process, 11 tracks were matched, of which 8 tracks were correctly matched and 3 were false tracks. The generated track results and the matched track results are shown below. Figure 4 and Figure 5 As shown. Statistics on correct and incorrect track matching results are as follows. Figure 6 As shown.

[0107] Example 3: System Structure

[0108] To implement the above method, the present invention also provides a target matching system based on the Doppler linear relationship of dual receiving stations, the system comprising:

[0109] 1. Receiver module: including receiver 1 and receiver 2, used to receive the echo signal after the transmitter signal is scattered by the target;

[0110] 2. Doppler Extraction Module: Performs spectral analysis or moving target detection on the echoes from each receiving station, and extracts the target Doppler frequency shift measurement;

[0111] 3. Candidate Generation Module: Generates candidate measurement pairs of Doppler signals from the two receiving stations based on conditions such as time, azimuth, and distance;

[0112] 4. Linear Modeling Module: Performs linear fitting on the two-dimensional Doppler point set formed by the candidate measurement pairs at multiple time points to obtain the slope and intercept;

[0113] 5. Matching Decision Module: Based on the preset slope range and linearity threshold, and combined with the slope value characteristics analyzed theoretically, the module performs matching decision on the candidate point set and outputs the decision result on whether they are the same target.

[0114] 6. Data Output Module: Provides the matching results to the upper-level trajectory tracking or data fusion module.

[0115] The above modules can be implemented through software, hardware, or a combination of both.

[0116] Implementation Method 4

[0117] This invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor. The memory stores software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory and processor are connected via a bus. Specifically, the processor implements any step in Embodiment 1 by running the computer program stored in the memory.

[0118] It should be understood that, in the embodiments of the present invention, the processor may be a Central Processing Unit (CPU), but it may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0119] Memory may include read-only memory, flash memory, and random access memory, and provides instructions and data to the processor. Some or all of the memory may also include non-volatile random access memory.

[0120] As can be seen from the above, the electronic device provided by the embodiments of the present invention can implement the shortwave radar Hough transform track initiation method as described in Embodiment 1 by running a computer program. The Hough transform is performed in the time-Doppler domain to initiate the track, which improves the accuracy and quality of track initiation of the shortwave radar and has strong robustness.

[0121] It should be understood that if the integrated modules / units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods described above can also be implemented by a computer program instructing related hardware. This computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0123] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this invention. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0124] It should be noted that the methods and detailed examples provided in the above embodiments can be incorporated into the apparatus and devices provided in the embodiments for mutual reference, and will not be repeated here.

[0125] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0126] In the embodiments provided by this invention, it should be understood that the disclosed apparatus / terminal devices and methods can be implemented in other ways. For example, the apparatus / device embodiments described above are merely illustrative. For instance, the division of modules or units described above is merely a logical functional division, and in actual implementation, it can be divided in other ways. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0127] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A target matching method based on the Doppler linear relationship of dual receiving stations, characterized in that, Includes the following steps: (1) In a radar or passive receiving system containing one transmitting station and at least two receiving stations, the Doppler frequency shift measurements of the target echo signal by the first receiving station and the second receiving station are acquired, and the Doppler measurement sequence set of the first receiving station and the Doppler measurement sequence set of the second receiving station are formed respectively. (2) Based on time, orientation, distance or other constraints, select candidate measurement sequence pairs from the first receiving station Doppler measurement set and the second receiving station Doppler measurement set; (3) For a candidate target, collect its Doppler frequency shift at the first and second receiving stations at multiple observation times to form a two-dimensional Doppler point set; (4) Perform linear fitting on the two-dimensional Doppler point set to obtain the slope and linearity evaluation index of the fitted line; (5) Based on the geometric relationship of the target motion and the geometric relationship of the dual receiving station layout, the Doppler frequency shift relationship between the first receiving station and the second receiving station is theoretically analyzed to determine the reasonable range of slope values ​​and the linearity threshold. (6) When the fitted slope falls within a reasonable range and the linearity evaluation index meets the decision threshold, it is determined that the Doppler measurements of the two receiving stations corresponding to the two-dimensional Doppler point set come from the same target; otherwise, it is determined that they are different targets or unreliable matching.

2. The target matching method based on the dual-receiving-station Doppler linear relationship according to claim 1, characterized in that, In step (4), the straight line fitting is performed using the least squares method, and the linearity evaluation index is the coefficient of determination of the fitted straight line. Or at least one of the mean square error.

3. The target matching method based on the dual-receiving-station Doppler linear relationship according to claim 1, characterized in that, The reasonable range of slope values ​​mentioned in step (5) is determined based on the geometric configuration of the dual receiving stations and the theoretical derivation and simulation analysis of the target heading angle.

4. A target matching system based on the Doppler linear relationship of dual receiving stations, characterized in that, The system is used to implement the target matching method based on dual-receiving-station Doppler linear relationship as described in any one of claims 1 to 3; the system comprises: The receiving station module is used to receive the echo signal of the signal transmitted by the transmitting station after it has been scattered by the target; The Doppler extraction module is used to perform Doppler processing on the echo signal and extract the Doppler frequency shift measurements of the first and second receiving stations. The candidate generation module is used to generate candidate measurement pairs from the Doppler measurement sets of the first and second receiving stations based on time, orientation, distance or other conditions. The linear modeling module is used to construct a two-dimensional Doppler point set from the Doppler measurements of the two receiving stations of the candidate target at multiple observation times, and to perform linear fitting on the point set to obtain the fitting slope and linearity evaluation index. The matching and determination module is used to perform matching and determination on the two-dimensional Doppler point set according to the preset reasonable value range of slope and linearity threshold. When the slope falls within the reasonable value range of slope and the linearity evaluation index meets the linearity threshold, the module outputs the determination result that the measurements of the two receiving stations are from the same target.

5. A target matching system based on dual-receiving-station Doppler linear relationship according to claim 4, characterized in that, The matching determination module is also used to perform theoretical analysis on the Doppler frequency shift relationship between the first and second receiving stations based on the geometric configuration of the dual receiving stations and the target motion model, and to determine the reasonable range of slope values ​​and linearity threshold in an offline manner.

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