Minimum path two-dimensional pairing method based on distributed radar

Abstract

The invention discloses a minimum path two-dimensional pairing method based on a distributed radar, and the method comprises the following steps: obtaining the path information of a distributed radar platform signal, selecting effective path data from the signal path, and forming effective path information; the types of the signal paths comprise self paths and mutual paths; n + 1 pairing paths are screened from the effective path information to form a pairing path data set, and N is the number of radars in the distributed radar platform; determining a distance dimension-Doppler dimension judgment condition; traversing the pairing path data set, extracting pairing paths of judgment conditions, and forming a successful pairing path data set; traversing the data set of the successfully paired paths, extracting targets corresponding to the successfully paired paths, and generating a pairing result; and screening the pairing results to generate a minimum path two-dimensional pairing result set. According to the technical scheme, the multi-path fusion problem during distributed radar detection can be solved, and the calculation complexity is reduced.

Description

Technical Field

[0001] The present invention relates to the field of distributed radar detection enhancement technology, and in particular to a minimum path two-dimensional pairing method based on distributed radar. Background Art

[0002] Distributed radar is a radar system that uses multiple radars to detect targets in a coordinated manner: each radar transmits an orthogonal signal and receives the transmission signals of all radars, and finally fuses the detection information to improve the overall detection performance of the entire system. The distributed radar system consists of multiple radar stations placed in multiple locations in space. Each radar transmits and receives signals at the same time, and the received target information will be fused and processed. Since the radars are located in different directions, the transmitted signals can detect the target from different directions through different propagation paths, and the target echo can also be transmitted to each radar through different propagation paths, thereby obtaining spatial diversity gain. Through multiple transmission and multiple reception, multipath fading can be well combated, mutual interference between signals can be reduced, and the performance of the system can be improved.

[0003] For distributed radar, the echo signals of different paths can provide gains through beamforming, matched filtering, moving target detection (MTD) and other methods. However, the echo signals between different paths cannot be directly superimposed to obtain diversity gain. Therefore, it is necessary to perform target extraction and pairing processing on the RV spectrum after MTD, eliminate noise with high amplitude, and match the position and velocity information of multiple targets.

[0004] When the performance of different distributed radar platforms is inconsistent, the success of the pairing process is greatly affected by the low-performance platform. Therefore, a pairing solution is needed that can screen low-performance platforms and reduce the use of low-performance platforms. When implementing pairing, the selection criterion of the minimum number of paths is implemented to reduce the computational complexity and improve the radar pairing efficiency. Summary of the invention

[0005] To achieve the above object, the present application provides a minimum path two-dimensional pairing method based on distributed radar, comprising the following steps:

[0006] Acquire path information of a distributed radar platform signal, select valid path data from the signal path, and form valid path information; the types of the signal path include self-path and mutual path;

[0007] N+1 paired paths are selected from the valid path information to form a paired path data set, where N is the number of radars in the distributed radar platform;

[0008] Determine the range dimension-Doppler dimension judgment condition;

[0009] The paired path data set is traversed to extract paired paths that meet the distance dimension-Doppler dimension judgment condition to form a paired successful path data set; the paired successful path data set includes path, amplitude, distance unit, and Doppler unit information.

[0010] Traverse the paired successful path data set, extract the target corresponding to the paired successful path, delete the invalid data without corresponding target, and generate the paired result;

[0011] The pairing results are screened to generate a minimum path two-dimensional pairing result set.

[0012] Among them, when obtaining the path information of the distributed radar platform signal, the signal generated by the radar is matched filtered, and the pulse pressure signal is processed by MTD to obtain the RV spectrum;

[0013] The selection of valid path data from the signal path is achieved by a path selection matrix A; the path selection matrix A is represented by A=[x1 x2...x j ] T ,and: Where j is the path number, i is the platform number and n <N, Select the index for the distance of path j to platform i;

[0014] According to the path selection matrix A, the path distance combination b is defined and expressed as and Define the path Doppler combination, expressed as: and

[0015] Furthermore, the range selection index is realized based on the matrix of the distance vector r, which is composed of the one-way path distance from the target to the corresponding radar, expressed as: r = [r1 r2 r i r n ] T , where r i Represents the distance from radar i to the target.

[0016] Furthermore, N+1 paired paths are selected from the valid path information, including:

[0017] Performing non-coherent pre-addition processing on the signal paths of the mutual paths;

[0018] Perform high signal-to-noise self-path selection on the signal of the self-path.

[0019] Further, when selecting N+1 paired paths from the valid path information, it includes: limiting That is, the path distance combination b is the actual distance combination extracted from the path selected by the first-level threshold corresponding to A; That is, the path Doppler combination f is the actual Doppler combination extracted from the path selected by the first-level threshold corresponding to A.

[0020] Among them, the range dimension-Doppler dimension judgment condition refers to:

[0021] |Self-path distance vector-full-rank mutual-path distance matrix × coefficient vector|<distance judgment threshold,

[0022] |Self-path Doppler vector - full-rank cross-path Doppler matrix × coefficient vector| < Doppler decision threshold;

[0023] The distance determination threshold is the maximum distance cell number by which the distance deviates from the expected value, and the Doppler determination threshold is the maximum Doppler cell number by which the Doppler deviates from the expected value.

[0024] When N=3, the range dimension-Doppler dimension determination condition is expressed as:

[0025]

[0026] Among them, ε1 is the distance determination threshold, and ε2 is the Doppler determination threshold.

[0027] When extracting the target corresponding to the successfully paired path, the self-path that did not participate in the pairing when the high signal-to-noise self-path selection was performed on the signal of the self-path is subjected to target judgment. If the target exists in the path, the path, amplitude, distance unit, and Doppler unit information are added to the pairing result.

[0028] Further, screening the pairing results refers to performing constant false alarm level 2 threshold screening on the pairing results.

[0029] According to the present invention, the problem of multi-path fusion during distributed radar detection can be solved. On the one hand, under normal circumstances, the original two-dimensional pairing scheme can be replaced without losing the detection probability; on the other hand, since the number of paths involved in pairing is reduced, its calculation complexity is reduced compared with the original two-dimensional pairing scheme; at the same time, in view of the situation where the performance of distributed platforms is not uniform, the present invention further improves the probability of detecting the real purpose compared with the traditional two-dimensional pairing scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a step diagram of a minimum path two-dimensional pairing method provided according to an embodiment of the present invention;

[0031] Figure 2 is a flow chart of a minimum path two-dimensional pairing algorithm provided according to an embodiment of the present invention;

[0032] Figure 3 is a constant false alarm detection probability curve diagram comparing the minimum path pairing method with other methods under the same platform conditions provided by an embodiment of the present invention;

[0033] Figure 4 It is a constant false alarm detection probability curve diagram comparing the minimum path pairing method with other methods under the low performance condition of the third platform reception provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] Distributed radar is a network composed of multiple radar sites with different locations but working in coordination. Through network connection and coordination, the limitation of a single radar at a single angle is broken through, and high-precision, all-round monitoring and tracking of targets are achieved. In general, the signal waveforms emitted by such radars need to have a low cross-correlation so that the radar can match and filter the separated signals when receiving. When a distributed radar platform detects one or more targets, the multipath information includes real target information and false target information, which cannot be separated due to mutual mixing, and the distance or platform performance of some distributed radar platforms leads to a low signal-to-noise ratio. In view of this situation, the present invention uses the minimum path pairing criterion to minimize the use of low signal-to-noise ratio, and uses the distance Doppler two-dimensional information to complete the target information pairing and the elimination of false targets, and finds the corresponding data of the same target on each path according to whether the distance and Doppler information of the target can meet the relationship between the distance and Doppler of different paths.

[0035] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings.

[0036] The minimum path two-dimensional pairing method provided by the present invention is as follows Figure 1 As shown, the following steps are included:

[0037] Step S100: Acquire path information of a distributed radar platform signal, select valid path data from the signal path, and form valid path information;

[0038] In this step, the distributed radar platform performs matched filtering on the signals generated by N radars, and performs MTD processing on the pulse compression signal to obtain the RV spectrum. In practical applications, when distributed radars with the same carrier frequency are working, one radar will receive echo signals from multiple radars. Therefore, path separation processing is also required in this step. By performing matched filtering on the transmission signals of different radars, the echo signals of the corresponding paths can be obtained to achieve path separation.

[0039] The types of signal paths for distributed radars to send signals to targets include self-paths and mutual paths. The signal path where the transmitting radar and the receiving radar are the same is a self-path, such as radar 1-target-radar 1; the signal path where the transmitting radar and the receiving radar are different is a mutual path, such as radar 1-target-radar 2 and radar 2-target-radar 1. The two paths in the example are represented as 1 transmit 2 receive and 2 transmit 1 receive respectively.

[0040] In this step, the separated path information is used to form valid path data.

[0041] In the effective path data, the distance from the target to the corresponding radar one-way path constitutes a matrix of distance vector r, which is expressed as r = [r1 r2 r i r n ] T , where r i represents the distance from radar i to the target, n is the number of radar platforms, n<=N, before pairing r i It is an objectively existing unknown quantity;

[0042] Based on the matrix of distance vector r, the path selection matrix A is defined, which is expressed as A = [x1 x2...x j ] T , and: vector Among them, j is the path number, J is the number of paths; in the path selection matrix, is the distance selection index of path j for platform i. For example, among radar platforms with N=3, radar 1 is a self-transmitting and self-receiving (1 transmit and 1 receive) path, and the path distance corresponding to radar 1 is 2r1, then the corresponding row vector is

[200] . If it is a mutual transmission and reception path between radar 1 and radar 2, their distance relationship is r1+r2, then the corresponding row vector is

[110] .

[0043] Based on the path selection matrix A, the path distance combination b is defined, expressed as Define the path Doppler combination, expressed as:

[0044] Step S110: According to the minimum pairing path rule, in this step, N+1 pairing paths are selected from the valid path information to form a pairing path data set, where N is the number of radars in the distributed radar platform.

[0045] Paired Path Dataset, from Path Selection Matrix Obtained in.

[0046] The specific implementation process is as follows Figure 2 As shown:

[0047] The present invention is described in detail for a distributed radar platform with N=3. As shown in step S200, in the case of three base stations (i.e., three radars), 9 paths of echo signal splitting are generated, i.e., the paths include 9 combinations, which can be expressed as:

[0048]

[0049]

[0050] The above paths include self-paths and mutual paths.

[0051] For the self-path, step S221 is performed to select a self-path with a higher signal-to-noise ratio;

[0052] For the mutual paths, since the signals of the mutual paths have the characteristic that the distance is the same and the Doppler is approximately the same, it is necessary to perform a non-coherent superposition operation of the RV spectra on them, that is, perform step S222, and perform non-coherent pre-superposition of the same group of mutual paths, that is, 1-in 2-out is fused with 2-in 1-out, 2-in 3-out is fused with 3-in 2-out, and 1-in 3-out is fused with 3-in 1-out;

[0053] Subsequently, the self-path and mutual path are respectively subjected to the first-level threshold screening of the self-path signal in step S231 and the first-level threshold screening of the mutual path in step S232, and N+1 paired path data are screened out based on the principle of shortest distance or best performance to form a path selection matrix corresponding to the paired path data set.

[0054] In this step, the valid path data is further limited. is the actual distance combination extracted from the path selected by the first-level threshold corresponding to A, The actual Doppler combination extracted by the path selected by the first-level threshold corresponding to A, in the specific definition, the amplitude of the first-level threshold passed by the data superimposed on the mutual paths is higher than the amplitude of the first-level threshold corresponding to the self-path.

[0055] Among them, in the non-coherent pre-stacking process, for far-field targets, the echo distance path transmitted by radar 1 and received by radar 2 is the same as that transmitted by radar 2 and received by radar 1. Under the condition of narrow-band frequency division with the same carrier frequency, the Doppler frequency reflecting the target speed can also be considered to be the same. Directly performing amplitude superposition and fusion on a pair of mutual paths in the RV spectrum stage can enhance the RV spectrum peak at the target. Especially when one of the paths is an inferior path, the pre-stacking operation can enhance the amplitude through its corresponding mutual path, so that the target signal that originally could not pass the first-level threshold can pass the first-level threshold.

[0056] The design of the first-level threshold can be designed as the peak value of m in the screening path (m is the number of data left in each path after the first-level threshold screening) in the case of N radar platforms. The final computational complexity of the algorithm is O(m N ). However, it is worth noting that due to the existence of inter-path pre-fusion, if there is no inter-path with a large difference in SNR, the SNR of the inter-path fusion will be higher than that of the self-path. Therefore, the threshold can be set higher than the inter-path to reduce the computational complexity.

[0057] The path selection matrix corresponding to the paired path data set finally formed in this step is expressed as:

[0058] The corresponding paths are: 1-in 2-out (i.e. mutual path 12), 2-in 2-out (i.e. mutual path 23), and 1-in 3-out (i.e. mutual path 13) after fusion; for the self-path, the 1-in 1-out (i.e. self-path 1) with higher signal-to-noise is selected using prior information, and the self-path 2 and self-path 3 with lower signal-to-noise are processed in subsequent steps.

[0059] Before extracting the paired paths that meet the distance dimension-Doppler dimension determination condition, the distance dimension-Doppler dimension determination condition needs to be determined.

[0060] Step S101: determining a range dimension-Doppler dimension determination condition;

[0061] The range dimension-Doppler dimension determination condition is:

[0062] |Self-path distance vector-full-rank mutual-path distance matrix × coefficient vector|<distance judgment threshold,

[0063] |Self-path Doppler vector-full-rank cross-path Doppler matrix×coefficient vector|<Doppler decision threshold.

[0064] For example, when N=3, the range dimension-Doppler dimension determination condition is expressed as:

[0065]

[0066] Among them, ε1 is the distance determination threshold, and ε2 is the Doppler determination threshold;

[0067] Specifically, the distance determination threshold ε1 is the maximum distance cell number by which the distance deviates from the expectation; and the Doppler determination threshold ε2 is the maximum Doppler cell number by which the Doppler deviates from the expectation.

[0068] Step S120: traversing the paired path data set, extracting paired paths that meet the distance dimension-Doppler dimension determination condition, and forming a paired successful path data set;

[0069] In this step, all N+1 path combinations are extracted from the path selection matrix obtained in step S110, and the path, amplitude, distance unit, and Doppler unit information are extracted from the path information. Combined with the distance dimension-Doppler dimension judgment condition defined in step S101, all outputs that meet the reduced path pairing relationship are obtained. The outputs that meet the conditions constitute the paired successful path data set (such as Figure 2 Step S240).

[0070] Step S130: traverse the paired successful path data set, extract the target corresponding to the paired successful path, delete invalid data without corresponding target, and generate a pairing result;

[0071] In this step, it is checked whether there is a target in all the paths in the paired path data set. If so, it is added to the pairing result according to the path, amplitude, range unit, and Doppler unit information (such as Figure 2 Step S250);

[0072] On the other hand, the self-paths not participating in the pairing are supplemented. For example, in the example of N=3 proposed by the present invention, when the high signal-to-noise self-path selection is performed on the signals of the self-paths, the self-paths not participating in the pairing, such as self-path 2 and self-path 3, are judged by the following method:

[0073] The path that has passed the judgment is also judged whether there is a target. If there is a target in the path, the path, amplitude, distance unit, and Doppler unit information are added to the pairing result. This information can be combined with the angle measurement to restore the coordinate position later.

[0074] In this step, the result of step 120 is paired and supplemented. For the combination that meets the pairing condition, the possible RV spectrum positions of all other paths can be calculated according to the range-Doppler relationship. The data that meets the range-Doppler two-dimensional determination threshold is searched in the data that passes the threshold for the corresponding path. If it exists, it is added to the pairing combination. If it does not exist, the corresponding amplitude is set to zero to mark the path data as unavailable.

[0075] Step S140: Generate a minimum path two-dimensional pairing result set.

[0076] In this step, the pairing result generated in step S130 is screened by the constant false alarm level 2 threshold (e.g. Figure 2 Step S260), obtaining the final minimum path two-dimensional pairing result set.

[0077] The present invention provides a scenario of simulating three radars detecting a single target: the three radars can receive and process the transmission signals of other radars, thus generating a total of 9 paths. The three-platform two-dimensional pairing algorithm provided by the present invention generates 4 successfully paired path data. The simulation inputs the RV spectrum data processed by the echo signals of each path into the 4 successful path data, and outputs the corresponding information of successful pairing. The simulation adopts the Monte Carlo method, sets the false alarm probability to be constant at 0.01%, and the first-level threshold data screening rate to 1%. 500 repeated experiments are performed in the signal-to-noise ratio range of 4-18dB and the interval of 1dB. The number of successfully paired target points is recorded in each experiment, and the detection probability curve is plotted to verify the detection performance of this spatial registration system. Figure 3 As shown in the figure, under the same signal-to-noise ratio conditions, the detection performance of the minimum path pairing scheme is higher than that of the traditional two-dimensional pairing scheme.

[0078] The simulation experiment also compared the single target detection performance under two conditions: the condition of uniform performance of all platforms and the condition of the third platform being a low-performance platform (the receiving gain is 5dB less than other platforms). At the same time, a single platform comparison group was set up to ensure the rationality of the experimental design. Figure 4 As shown in the figure, under the condition of a 5dB drop in the receiving signal-to-noise ratio of a single missile, its detection performance can be improved by 2.5dB at a 90% detection probability and 3dB at a 99% detection probability compared to the traditional solution. The reason for not achieving a 5dB attenuation of a single missile is that the receiving signal-to-noise ratio of the third platform decreases, resulting in a decrease in the 1-3 and 2-3 inter-path pre-fusion signal-to-noise ratios.

[0079] The present invention utilizes the minimum pairing criterion and the known low signal-to-noise ratio of the expected partial path to screen the pairing paths; finally, the pairing algorithm of reduced paths is used to screen the data processed by the distributed radar, so as to eliminate false targets and select the best performance true targets, so as to realize the optimal path pairing of the distributed radar platform.

[0080] The above disclosures are only several specific embodiments of the present invention; however, the present invention is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A minimum path two-dimensional pairing method based on distributed radar, characterized in that: The following steps are involved: Acquire path information of a distributed radar platform signal, select valid path data from the signal path, and form valid path information; the types of the signal path include self-path and mutual path; Selecting N+1 paired paths from the valid path information to form a paired path data set, where N is the number of radars in the distributed radar platform; Determine the range dimension-Doppler dimension judgment condition; Traversing the paired path data set, extracting paired paths that meet the distance dimension-Doppler dimension determination condition, and forming a paired successful path data set; Traversing the paired successful path data set, extracting the target corresponding to the paired successful path, deleting invalid data without corresponding target, and generating a pairing result; The pairing results are screened to generate a minimum path two-dimensional pairing result set.

2. The minimum path two-dimensional pairing fusion method according to claim 1, characterized in that: When obtaining the path information of the distributed radar platform signal, matching filtering is performed on the signal generated by the radar, and the pulse compression signal is subjected to MTD processing to obtain the RV spectrum; The selection of valid path data from the signal path is implemented by a path selection matrix A; the path selection matrix A is represented by A=[x1x2...x j ] T ,and: Where j is the path number, i is the platform number and n <N, Select the index for the distance of path j to platform i; According to the path selection matrix A, the path distance combination b is defined as: Define the path Doppler combination f, expressed as:

3. The minimum path two-dimensional pairing fusion method according to claim 2, characterized in that: The distance selection index is realized based on the matrix of the distance vector r, which is composed of the one-way path distance from the target to the corresponding radar, expressed as: r = [r1r2r i r n ] T , where r i Represents the distance from radar i to the target.

4. The minimum path two-dimensional pairing fusion method according to claim 2, characterized in that: The screening of N+1 paired paths from the valid path information includes: Performing non-coherent pre-addition processing on the signal paths of the mutual paths; Perform high signal-to-noise self-path selection on the signal of the self-path.

5. The minimum path two-dimensional pairing fusion method according to claim 1, characterized in that: The distance dimension-Doppler dimension determination condition refers to: |Self-path distance vector-full-rank mutual-path distance matrix × coefficient vector|<distance judgment threshold, |Self-path Doppler vector - full-rank cross-path Doppler matrix × coefficient vector| < Doppler decision threshold; The distance determination threshold is the maximum distance cell number by which the distance deviates from the expected value, and the Doppler determination threshold is the maximum Doppler cell number by which the Doppler deviates from the expected value.

6. The minimum path two-dimensional pairing fusion method according to claim 1, characterized in that: The successfully paired path data set includes path, amplitude, range unit, and Doppler unit information.

7. The minimum path two-dimensional pairing fusion method according to claim 4, characterized in that: When extracting the target corresponding to the successfully paired path, when performing high signal-to-noise self-path selection on the signal of the self-path, the self-path that does not participate in the pairing is judged as a target. If it exists in the path, the path, amplitude, distance unit, and Doppler unit information are added to the pairing result.

8. The minimum path two-dimensional pairing fusion method according to claim 1, characterized in that: The screening of the pairing results refers to performing constant false alarm level 2 threshold screening on the pairing results.

9. The minimum path two-dimensional pairing fusion method according to claim 5, characterized in that: When N=3, the range dimension-Doppler dimension determination condition is expressed as: Among them, ε1 is the distance determination threshold, and ε2 is the Doppler determination threshold.

10. The minimum path two-dimensional pairing fusion method according to claim 4, characterized in that: When selecting N+1 paired paths from the valid path information, it includes: limiting That is, the path distance combination b is the actual distance combination extracted from the path selected by the first-level threshold corresponding to A; That is, the path Doppler combination f is the actual Doppler combination extracted from the path selected by the first-level threshold corresponding to A.

Images