Active track deception jamming identification method and system for radar network

Abstract

The present invention discloses an active track deception interference identification method for radar network, including: S1 obtains pulse train signals in radar reconnaissance channel and radar interference channel, and extracts slow time domain data in the pulse train; S2 calculates the pulse arrival time difference between radar reconnaissance channel and radar interference channel based on the slow time domain data extracted in S1; S3 calculates the bandwidth of the pulse signal of radar interference channel based on the slow time domain data extracted in S1; S4 compares and determines the parameters obtained in the above steps with the preset threshold, identifies the interference type and / or pseudo radar echo; S5 calculates the Doppler information characteristics and time domain and frequency domain characteristics of the pulse train signal of the radar reconnaissance channel for the pseudo radar echo obtained in S4, compares and determines with the preset threshold, and outputs the final identification result after self-checking the determination result. The present invention also provides a system based on the above method. The present invention is simple to operate, and improves the accuracy of identification while ensuring the speed of identifying the radar interference type.

Description

Technical Field

[0001] The present invention relates to the technical field of active deception interference identification in radar network confrontation, and in particular to an active track deception interference identification method and system for radar network. Background Art

[0002] With the development of electromagnetics and signal processing, radar electronic countermeasures (ECCM) and radar electronic countermeasures (ECM) have become an extremely important part of modern warfare. Recent modern wars have also shown that the ownership of the space electromagnetic spectrum determines the direction of the war. The environment currently faced by radars is ever-changing, and active deception interference is highly targeted. Although the overall equipment level of our army's radars has been greatly improved, the anti-interference effect is still not ideal. The detection and identification of active deception interference types depends to a large extent on the operator's experience. In a complex electronic warfare environment, it is difficult for operators to correctly detect active deception interference and identify its type in real time. Radar network track disruption interference mainly uses the distance, speed, angle and other information carried by the false target to deceive the radar, and generates associated false targets by designing the spatial distribution of false targets to destroy the already formed track. Make the radar network unable to track the real target normally.

[0003] The common system process of radar anti-interference using signal processing algorithms is as follows: first, the interference type of the radar received signal is identified, then an effective suppression algorithm is selected based on the identification result to effectively suppress the interference signal, and finally the suppression effect is evaluated, and the evaluation result is fed back to the interference suppression module to select the optimal suppression algorithm. It can be seen from the anti-interference process that the detection and identification of high-probability active deception interference is the basis of the entire radar anti-interference. Therefore, it is very meaningful to study new algorithms and technologies for radar active deception interference to improve the radar's anti-interference performance.

[0004] At present, there are two methods for identifying active interference. One is offline active interference identification. This method needs to analyze the generation mechanism of various typical interference modes before identification, summarize the characteristics in the time domain, frequency domain and change domain, summarize the characteristic parameters of various interference types, and establish a characteristic parameter library of interference types. In the electronic warfare environment, the characteristic parameters of the received signal are first calculated, and various identification methods are used to detect and classify them in combination with some prior information in the training stage. This method has a high recognition probability but cannot achieve a fast response of the anti-interference system. Therefore, it can only target long-term fixed active deception interference sources. The other is an online real-time processing method. This method extracts characteristic parameters of the real-time received signal to find the subtle differences between the ideal echo signal and the interference signal, including fluctuation parameters, contrast, normalized spectrum mean, normalized energy ratio, symmetry, normalized spectrum correlation, normalized spectrum reverse moment and other characteristic parameters. Multiple characteristic parameters are effectively fused to identify various types of active deception interference types. This method has strong real-time performance, but it can only be used against radars of a specific system or individual active deception interference methods, and the recognition probability is low.

[0005] Patent document CN104267379A discloses a waveform design-based active and passive radar collaborative anti-interference method, including an active and passive radar collaborative anti-interference method, which can detect echo signals and use the passive part to estimate interference-related parameters to design the transmission waveform parameters of the active radar to achieve the purpose of interference identification and confrontation. Although this method can identify more types of interference, the architecture belongs to a multi-mode radar, and the engineering implementation is complex. Compared with active radar, an additional set of hardware circuits needs to be added.

[0006] Patent document CN107462873A discloses a method for rapid identification of radar interference, including:

[0007] With AGC mutation as the advance, multi-target detection is performed, and the type of signal currently entering the range gate is comprehensively judged based on the relationship between multiple targets or the change in waveform entropy. This method is based on detecting the change of the AGC value in each frame of radar echo signal, so as to identify multiple types of interference, but because it is only based on a single AGC value, the identification result can only stay in the general category of interference type, which is not enough to provide effective guidance and suggestions for subsequent anti-interference methods. Summary of the invention

[0008] In order to solve the above problems, the present invention provides an active track deception interference identification method for radar network. The method is based on the information analysis within the pulse string in the radar signal, which effectively improves the recognition speed and recognition accuracy of the radar network track interference type.

[0009] An active track deception jamming identification method for a radar network, comprising:

[0010] S1 obtains the pulse train signals in the radar reconnaissance channel and the radar jamming channel, and extracts the slow time domain data in the pulse train;

[0011] S2 calculates the pulse arrival time difference between the radar reconnaissance channel and the radar jamming channel based on the slow time domain data extracted from S1;

[0012] S3 calculates the Doppler information characteristics of the radar jamming channel pulse train signal based on the slow time domain data extracted in S1, and obtains the bandwidth of the radar jamming channel pulse signal;

[0013] S4 compares and determines with a preset threshold based on the pulse arrival time difference obtained by S2 and the bandwidth of the radar interference channel pulse signal obtained by S3, and identifies the interference type and / or pseudo radar echo;

[0014] S5 calculates the Doppler information characteristics and time domain and frequency domain characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo output in S4, compares and determines with the preset threshold, performs self-check on the determination result, and outputs the final recognition result.

[0015] Preferably, the radar network adopts a dual-channel design and can receive two polarization signals at the same time, thereby eliminating the analysis and calculation process of the original radar signal and further speeding up the recognition work efficiency.

[0016] Preferably, the slow time domain data extraction process: N p The received signal samples are obtained by in is the discrete data within a single pulse repetition period, []′ represents transposition, N f is the sampling point within a single pulse repetition period, i=1,2,3…N p is a slow time domain sequence. Based on the above data, the data matrix X T Vectorize and obtain vector That is, the slow time domain data corresponding to the pulse signal.

[0017] Preferably, the pulse arrival time difference in S2 is specifically:

[0018] Record the reception time of the first pulse in the radar reconnaissance channel signal and the radar interference channel signal respectively, and calculate the difference TDA1 between the two;

[0019] Simultaneously record the Nth signal in the radar reconnaissance channel and the radar jamming channel toaThe receiving time of the pulses is calculated, and the difference between the two is TDA. N , where N toa The parameters are set in advance;

[0020] The pulse arrival time difference = |TDA N -TDA1|.

[0021] Preferably, the preset threshold is preset in advance based on the actual confrontation scenario and specific parameters of the radar network equipment.

[0022] Preferably, the comparison and determination in S4 is specifically:

[0023] If the pulse arrival time difference is greater than the preset threshold, and the bandwidth of the radar jammer channel pulse signal is greater than the preset threshold, it is determined to be a combined range and speed drag jammer;

[0024] If the pulse arrival time difference is greater than the preset threshold, and the bandwidth of the radar jammer channel pulse signal is less than or equal to the preset threshold, it is determined to be range-drag jammer;

[0025] If the pulse arrival time difference is less than or equal to the preset threshold, and the bandwidth of the radar jammer channel pulse signal is greater than the preset threshold, it is determined to be speed drag interference;

[0026] If the pulse arrival time difference is less than the preset threshold and the bandwidth of the radar interference channel pulse signal is less than the preset threshold, it is judged as a pseudo radar echo.

[0027] Preferably, the comparison and determination in S5 is specifically:

[0028] S5.1 calculates the FFT peak coordinates in the slow time domain data of the two pulse train signals based on the Doppler information characteristics of the radar jamming channel pulse train signal obtained in S3 and the Doppler information characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo, and records the difference in the horizontal coordinate distance between the two as the spectrum peak distance:

[0029] If the spectrum peak distance is greater than the preset threshold, it is determined to be a false speed target interference;

[0030] If the spectrum peak distance is less than or equal to the preset threshold, the next step of determination is carried out;

[0031] S5.2 calculates the corresponding instantaneous amplitude spectrum maximum value and energy ratio by normalizing the time domain and frequency domain characteristics corresponding to the pseudo radar echo:

[0032] If the maximum value of the instantaneous amplitude spectrum is greater than the preset threshold and the energy ratio is greater than the preset threshold, it is determined to be a false target interference;

[0033] If the maximum value of the instantaneous amplitude spectrum is less than or equal to the preset threshold, it is determined to be a radar echo.

[0034] Preferably, the self-check in S5 is specifically as follows: for the results determined as radar echoes, majority logic determination fusion is performed, that is, if the number of radar echoes determined in the radar network is greater than a preset threshold, the output determination result is radar echo.

[0035] The present invention also embodies a system based on an active track deception interference identification method. The system is simple to operate and can identify the interference type simply by acquiring a pulse train signal in a radar signal.

[0036] A system for identifying an active track deception interference method, comprising:

[0037] A signal acquisition module is used to acquire pulse train signals in the radar reconnaissance channel and the radar jamming channel;

[0038] A signal calculation module, which calculates relevant data used for determination based on the pulse train signal obtained by the signal acquisition module;

[0039] Input module, used for operators to set preset thresholds;

[0040] The analysis module identifies and determines the signal based on the relevant data calculated in the signal calculation module and the preset threshold set in the input module;

[0041] The output module is used to output the recognition and judgment results of the analysis module.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) Analyze the pulse train signal in the radar signal and quickly compare it with the preset threshold to identify the interference type, thereby improving the recognition efficiency.

[0044] (2) The dual-channel radar group network system can receive two polarization signals at the same time, thus eliminating the need to analyze and calculate the original radar signal, further speeding up the recognition efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A technical flow chart of the active track deception interference identification method provided by the present invention;

[0046] Figure 2 A schematic diagram of the structure of a system for implementing the active track deception interference identification method of the present invention;

[0047] Figure 3 This is the FFT diagram of the interference channel signal that does not contain speed drag information in this embodiment;

[0048] Figure 4This is an FFT diagram of the interference channel signal containing speed drag information in this embodiment;

[0049] Figure 5 This is the curve of target recognition accuracy changing with signal-to-noise ratio. DETAILED DESCRIPTION

[0050] The method provided by the present invention is verified by computer simulation, wherein the environmental parameters are set as:

[0051] The speed of light c = 3 × 10 8 m / s; signal sampling rate F s =250MHz, the carrier frequency of the radar pulse is F c =300MHz, the bandwidth of the radar transmission pulse B = 10MHz, the pulse width of the radar transmission pulse PW = 5μs, and the repetition period of the radar transmission pulse PRI = 500μs. The number of interval pulses N selected for the arrival time of the radar reconnaissance channel and the interference channel signal toa =100, the number of pulses extracted in the slow time domain N p =100, the number of FFT points before and after the interference signal of the radar interference channel is N subfft =32, the number of FFT points N for comparing the echo signal of the radar reconnaissance channel with the interference signal of the interference channel fft =128.

[0052] The preset parameters of each substation of the radar network are shown in the following table:

[0053] Radar 1 Radar 2 Radar 3 Signal pulse width / μs 10 5 10 Signal bandwidth / MHz 5 10 10 Working frequency / GHz 3 1.5 2.5

[0054] Since the method of the present invention is mainly performed in the signal processing domain, the radar station topology has almost no effect on the recognition result.

[0055] like Figure 1 The active track deception interference identification method for radar network comprises:

[0056] S1 obtains the pulse train signals in the radar reconnaissance channel and the radar jamming channel, and extracts the slow time domain data in the pulse train: p The received signal samples are obtained by in is the discrete data within a single pulse repetition period, []′ represents transposition, N f is the sampling point within a single pulse repetition period, i=1,2,3…N p is a slow time domain sequence. Based on the above data, the data matrix X T Vectorize and obtain vector That is, the slow time domain data corresponding to the pulse signal.

[0057] S2 calculates the pulse arrival time difference between the radar reconnaissance channel and the radar jamming channel based on the slow time domain data extracted from S1:

[0058] S2.1 records the receiving time TOA of the first pulse of the radar reconnaissance channel signal r1 , the receiving time TOA of the 100th pulse r100 , and record the receiving time TOA of the first pulse of the radar interference channel signal j1 , the receiving time TOA of the 100th pulse j100 ;

[0059] S2.2 calculates the time difference of the two channels respectively:

[0060] TDA1=|TOA r1 -TOA j1 |

[0061] TDA 100 =|TOA r100 -TOA j100 |

[0062] S2.3 TDA1 and TDA obtained based on S2.2 100 , calculate the pulse time difference:

[0063] T 1-100 =|TDA 100 -TDA1|

[0064] Where T 1-100 is the pulse time difference.

[0065] S3 calculates the Doppler information characteristics of the radar jamming channel pulse train signal based on the slow time domain data extracted in S1, and obtains the bandwidth of the radar jamming channel pulse signal:

[0066] S3.1 performs FFT transformation on the first 32 points of the vector signal based on the slow time domain data extracted in S1 to obtain the front FFT graph corresponding to the slow time domain data;

[0067] S3.2 Based on the previous FFT graph, obtain the horizontal coordinate index_start corresponding to the previous FFT spectrum peak;

[0068] S3.3 takes the last 32 points of the vector signal and performs FFT transformation to obtain the last FFT diagram corresponding to the slow time domain data;

[0069] S3.4 Based on the latter FFT graph, obtain the horizontal coordinate index_end corresponding to the latter FFT spectrum peak;

[0070] S3.5 Calculate the bandwidth of the radar jammer channel pulse signal:

[0071] F d_subdiff =|index start -index_end|

[0072] where F d_subdiff is the bandwidth of the radar jammer channel pulse signal.

[0073] S4 compares the pulse arrival time difference obtained by S2 and the bandwidth of the radar interference channel pulse signal obtained by S3 with the preset threshold to identify the interference type and / or pseudo radar echo:

[0074] In this embodiment, the preset thresholds TH_subfft=1, TH_toa=5;

[0075] If T 1-100 >TH_toa and F d_subdiff >TH_subfft, the interference type is determined to be distance-speed combined drag;

[0076] If T 1-100 >TH_toa and F d_subdiff ≤TH_subfft, the interference type is determined to be distance drag;

[0077] If T 1-100 ≤TH_toa and F d_subdiff >TH_subfft, the interference type is determined to be speed drag;

[0078] If T 1-100 ≤TH_toa and F d_subdiff ≤TH_subfft, it is preliminarily determined to be a pseudo radar echo.

[0079] S5 calculates the Doppler information characteristics and time domain and frequency domain characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo output in S4, compares and determines with the preset threshold, performs self-check on the determination result, and outputs the final recognition result:

[0080] S5.1 calculates the FFT peak coordinates in the slow time domain data of the two pulse train signals based on the Doppler information characteristics of the radar jamming channel pulse train signal obtained in S3 and the Doppler information characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo, and records the difference in the horizontal coordinate distance between the two as the spectrum peak distance:

[0081] If the spectrum peak distance is greater than the preset threshold, it is determined to be a false speed target interference;

[0082] If the spectrum peak distance is less than or equal to the preset threshold, the next step of determination is carried out;

[0083] S5.2 calculates the corresponding instantaneous amplitude spectrum maximum value and energy ratio by normalizing the time domain and frequency domain characteristics corresponding to the pseudo radar echo:

[0084] Assume that the continuous time of the radar receiving signal is x(t), and use the frequency F s Collect it and get the sequence x(n), where n = 1, 2...N s ,N s Sleep for sampling point;

[0085] Perform Hilbert transform on the sampling sequence x(n) to extract the instantaneous amplitude of the signal:

[0086]

[0087] Compute the maximum value of the normalized instantaneous amplitude spectrum:

[0088]

[0089] where γ max is the maximum value of the normalized instantaneous amplitude spectrum, which is used to distinguish signals containing amplitude fluctuation information and signals without amplitude fluctuation information. cn (n) is the zero-centered normalized instantaneous amplitude:

[0090] Calculate the normalized left-right energy ratio of the sampling sequence x(n):

[0091]

[0092] in The energy ratio is based on the difference in effective value of the signal within a fixed window length M. This feature mainly reflects the difference in energy between the left and right parts of the sequence window. The more obvious the difference in the capacity between the left and right parts, the larger the ER value, and vice versa.

[0093] If γ max >TH_γ&&ER>TH_ER, it is determined to be a false target interference, where the threshold TH in this embodiment γ =2.5, TH_ER=0.1;

[0094] If the maximum value of the instantaneous amplitude spectrum is less than or equal to the preset threshold, it is determined to be a radar echo.

[0095] Self-check the judgment result: For the result judged as radar echo, perform majority logic judgment fusion, that is, if the number of radar echoes judged as radar echoes in the radar network is greater than the preset threshold, the output judgment result is radar echo: When the same local receiver is used, the preset threshold in the majority logic criterion in It means rounding up, N is the number of receivers in the radar network. When TH_K value is larger, the recognition accuracy is higher.

[0096] like Figure 2 As shown, a system based on a source track deception interference identification method comprises:

[0097] A signal acquisition module is used to acquire pulse train signals in the radar reconnaissance channel and the radar jamming channel;

[0098] A signal calculation module, which calculates relevant data used for determination based on the pulse train signal obtained by the signal acquisition module;

[0099] Input module, used for operators to set preset thresholds;

[0100] The analysis module identifies and determines the signal based on the relevant data calculated in the signal calculation module and the preset threshold set in the input module;

[0101] The output module is used to output the recognition and judgment results of the analysis module.

[0102] The operator only needs to preset the threshold to start identifying the radar signal.

[0103] like Figure 3 As shown in the figure, it is the FFT diagram corresponding to the interference channel signal of the active deception interference type that does not contain speed dragging information. If the channel difference is approximately 0, it is judged as a pseudo radar echo and enters the next step of identification. The solid line in the figure is the FFT peak of the first 32 points, and the dotted line is the FFT peak of the last 32 points.

[0104] like Figure 4 As shown, this is the FFT diagram corresponding to the interference channel signal of the active deception interference type containing speed dragging information. It can be seen intuitively that the difference between the two channels is 8, which is greater than the threshold. It can be directly determined as speed dragging interference, and then it can be specifically classified according to the classification method in S4. The solid line in the figure is the FFT peak of the first 32 points, and the dotted line is the FFT peak of the last 32 points.

[0105] like Figure 5 As shown, under the simulation conditions of this embodiment, the target recognition probability increases with the increase of the signal-to-noise ratio. When the signal-to-noise ratio is greater than 4dB, the correct recognition probability is greater than 80%, which means that the recognition method provided by the present invention has good recognition ability.

Claims

1. A radar network-oriented active track deception jamming identification method, characterized in that: include: S1 obtains the pulse train signals in the radar reconnaissance channel and the radar jamming channel, and extracts the slow time domain data in the pulse train; S2 calculates the pulse arrival time difference between the radar reconnaissance channel and the radar jamming channel based on the slow time domain data extracted from S1; S3 calculates the Doppler information characteristics of the radar jamming channel pulse train signal based on the slow time domain data extracted in S1, and obtains the bandwidth of the radar jamming channel pulse signal; S4 compares and determines with a preset threshold based on the pulse arrival time difference obtained by S2 and the bandwidth of the radar interference channel pulse signal obtained by S3, and identifies the interference type and / or pseudo radar echo; S5 calculates the Doppler information characteristics and time domain and frequency domain characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo output in S4, compares and determines with the preset threshold, performs self-check on the determination result, and outputs the final recognition result.

2. The active track deception jamming identification method according to claim 1, characterized in that: The slow time domain data extraction process: N p The received signal samples are obtained by in is the discrete data within a single pulse repetition period, []′ represents transposition, N f is the sampling point within a single pulse repetition period, i=1,2,3…N p is a slow time domain sequence. Based on the above data, the data matrix X T Vectorize and obtain vector That is, the slow time domain data corresponding to the pulse signal.

3. The active track deception jamming identification method according to claim 1, characterized in that: The pulse arrival time difference in S2 is specifically: Record the reception time of the first pulse in the radar reconnaissance channel signal and the radar interference channel signal respectively, and calculate the difference TDA1 between the two; Simultaneously record the Nth signal in the radar reconnaissance channel and the radar jamming channel toa The receiving time of the pulses is calculated, and the difference between the two is TDA. N ; The pulse arrival time difference = |TDA N -TDA1|.

4. The active track deception jamming identification method according to claim 1, characterized in that: The preset threshold is preset in advance based on the actual confrontation scenario and specific parameters of the radar network equipment.

5. The active track deception jamming identification method according to claim 1, characterized in that: The comparison and determination in S4 is specifically as follows: If the pulse arrival time difference is greater than the preset threshold, and the bandwidth of the radar jammer channel pulse signal is greater than the preset threshold, it is determined to be a combined range and speed drag jammer; If the pulse arrival time difference is greater than the preset threshold, and the bandwidth of the radar jammer channel pulse signal is less than or equal to the preset threshold, it is determined to be range-drag jammer interference; If the pulse arrival time difference is less than or equal to the preset threshold, and the bandwidth of the radar jammer channel pulse signal is greater than the preset threshold, it is determined to be speed drag interference; If the pulse arrival time difference is less than the preset threshold and the bandwidth of the radar interference channel pulse signal is less than the preset threshold, it is judged as a pseudo radar echo.

6. The active track deception jamming identification method according to claim 1, characterized in that: The comparison and determination in S5 is specifically as follows: S5.1 calculates the FFT peak coordinates in the slow time domain data of the two pulse train signals based on the Doppler information characteristics of the radar jamming channel pulse train signal obtained in S3 and the Doppler information characteristics of the radar reconnaissance channel pulse train signal of the pseudo radar echo, and records the difference in the horizontal coordinate distance between the two as the spectrum peak distance: If the spectrum peak distance is greater than the preset threshold, it is determined to be a false speed target interference; If the spectrum peak distance is less than or equal to the preset threshold, the next step of determination is carried out; S5.2 calculates the corresponding instantaneous amplitude spectrum maximum value and energy ratio by normalizing the time domain and frequency domain characteristics corresponding to the pseudo radar echo: If the maximum value of the instantaneous amplitude spectrum is greater than the preset threshold and the energy ratio is greater than the preset threshold, it is determined to be a false target interference; If the maximum value of the instantaneous amplitude spectrum is less than or equal to the preset threshold, it is determined to be a radar echo.

7. The active track deception jamming identification method according to claim 1, characterized in that: The self-check in S5 is specifically: for the result determined as radar echo, majority logic determination fusion is performed, that is, if the number of radar echoes determined in the radar network is greater than a preset threshold, the output determination result is radar echo.

8. A system for implementing the active track deception interference identification method according to any one of claims 1 to 7, characterized in that: include: A signal acquisition module is used to acquire pulse train signals in the radar reconnaissance channel and the radar jamming channel; A signal calculation module, which calculates relevant data used for determination based on the pulse train signal obtained by the signal acquisition module; Input module, used for operators to set preset thresholds; The analysis module identifies and determines the signal based on the relevant data calculated in the signal calculation module and the preset threshold set in the input module; The output module is used to output the recognition and judgment results of the analysis module.

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