A radar active composite jamming type identification method

Abstract

The present application relates to a kind of radar active composite jamming type identification method, comprising: constructing radar active jamming database, multiple interference types of radar active jamming signal of the suppression jamming, deception jamming and suppression-deception composite jamming are contained in radar active jamming database;The feature analysis extraction of all radar active jamming signals is carried out, the corresponding characteristic parameter is obtained, and the characteristic parameter library of radar active jamming signal is constructed;Wherein, characteristic parameter includes local equivalent noise jamming ratio, sliding correlation coefficient peak value of interference signal and transmitting signal.The statistical analysis of the characteristic parameter of characteristic parameter library is carried out, the characteristic parameter threshold value of interference signal classification is determined, and statistical decision tree is constructed;The interference type identification of the radar active jamming signal to be measured is realized using statistical decision tree.The present application method extracts characteristic parameter by analyzing the generation mechanism of interference signal and constructs classification tree, and effectively improves the identification accuracy of radar commonly used active jamming.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of radar, and particularly relates to a radar active composite jamming type identification method. BACKGROUND

[0002] The most basic function of a radar is to detect and measure the distance of a target by using radio waves. However, in practical applications, the target is often in a complex electromagnetic interference environment, and the existence of other interference signals of non-target signals causes serious interference to the normal operation of the radar. According to the different energy sources, the interference can be divided into two categories: active interference and passive interference. Generally, we call the interference formed by the scattering, reflection or refraction of electromagnetic waves by non-detection targets as passive interference, and the interference caused by the use of a specific jammer to retransmit or emit a certain electromagnetic wave to disturb the normal operation of the radar of the other party as active interference. Generally, the jammer can generate a specific type of interference according to the working parameters and specific purposes of the radar, and thus is more targeted and flexible. In actual work, the influence of active interference on the radar is greater than that of passive interference, and thus active interference is the main research object of radar interference identification and suppression.

[0003] So far, the research on interference identification methods at home and abroad mainly focuses on two related interference identification methods: maximum likelihood criterion and feature extraction. Among them, the maximum likelihood criterion is to combine the prior information received by the radar and the experience of the radar operator to determine the type of interference by means of traditional signal processing. The disadvantage of this method is that the amount of calculation is large, and it is not easy to implement in engineering. At the same time, due to the subjective nature of manual operation, the reliability of the determination result is poor. In order to make up for the shortcomings of the maximum likelihood criterion method, the existing technology proposes an interference identification algorithm based on feature extraction. This method refers to combining the interference generation mechanism to mine the differences between signals in the time domain, frequency domain, time-frequency domain and other transform domains, so as to extract feature parameters with distinguishability, and then use a decision tree classifier to identify them. However, there are still some problems, including how to find features with obvious distinguishing degree, and how to identify composite interference signals in which suppressive interference and deceptive interference exist at the same time. SUMMARY

[0004] In order to solve the above problems in the prior art, the present application provides a radar active composite jamming type identification method. The technical problem to be solved by the present application is solved by the following technical scheme:

[0005] The present application provides a radar active composite jamming type identification method, which comprises the following steps:

[0006] Step 1: Construct a radar active interference database, wherein the radar active interference database contains radar active interference signals of multiple interference types including suppressive interference, deceptive interference and suppressive-deceptive composite interference;

[0007] Step 2: feature analysis and extraction are performed on all radar active jamming signals in the radar active jamming database to obtain corresponding feature parameters, and a feature parameter library of radar active jamming signals is constructed by using the feature parameters; wherein the feature parameters include a local equivalent jam-to-noise ratio, and a sliding correlation coefficient peak value of a jamming signal and a transmitted signal;

[0008] Step 3: statistical analysis is performed on the feature parameters of the feature parameter library to determine a feature parameter threshold value of jamming signal classification, and a statistical decision tree is constructed according to the feature parameter threshold value;

[0009] Step 4: the statistical decision tree is used to realize identification of a jamming type of a to-be-tested radar active jamming signal.

[0010] In an embodiment of the present application, the step 1 comprises: using simulation to generate a plurality of radar active jamming signals, and labeling a corresponding jamming type label for each radar active jamming signal;

[0011] Among them, the plurality of radar active jamming signals include: radar active jamming signals of two kinds of suppressive noise jamming, namely noise amplitude modulation aiming jamming and noise frequency modulation blocking jamming, radar active jamming signals of two kinds of deceptive jamming, namely false target jamming and intermittent sampling retransmission jamming, and radar active jamming signals of two kinds of composite jamming, namely suppressive noise jamming-false target jamming and suppressive noise jamming-intermittent sampling retransmission jamming.

[0012] In an embodiment of the present application, the step 2 comprises:

[0013] A time domain amplitude peak value of the radar active jamming signal is determined, a signal with a window length of 2M is taken with the time domain amplitude peak value as the center to obtain a first window signal, wherein M is the length of the transmitted signal;

[0014] A ratio of a signal amplitude mean value to a noise mean value of the first window signal is calculated to obtain a local equivalent jam-to-noise ratio of the first window signal, and a sliding correlation coefficient peak value of a jamming signal corresponding to the first window signal and a transmitted signal is calculated, wherein a sliding window length is the length M of the transmitted signal, and a sliding window interval is 1;

[0015] For a radar active jamming signal of a composite jamming type, a second window signal is obtained after the first window signal is removed from the radar active jamming signal;

[0016] A ratio of a signal amplitude mean value to a noise mean value of the second window signal is calculated to obtain a local equivalent jam-to-noise ratio of the second window signal, and a sliding correlation coefficient peak value of a jamming signal corresponding to the second window signal and a transmitted signal is calculated;

[0017] According to the interference type label corresponding to all radar active jamming signals, the local equivalent jam-to-noise ratio corresponding to the first window signal and the sliding correlation coefficient peak value of the jamming signal and the transmitted signal, and the local equivalent jam-to-noise ratio corresponding to the second window signal and the sliding correlation coefficient peak value of the jamming signal and the transmitted signal, the feature parameter library is constructed.

[0018] In an embodiment of the present application, the step 3 comprises:

[0019] The interference type corresponding to the radar active jamming signal and the corresponding feature parameters are statistically plotted and analyzed to determine a first threshold, a second threshold, a third threshold, a fourth threshold and a fifth threshold; wherein the first threshold is a judgment threshold of the jamming signal, the second threshold is a judgment threshold of the false target jamming of the first window signal, the third threshold is a judgment threshold of the suppressive noise jamming of the first window signal, the fourth threshold is a judgment threshold of the false target jamming of the second window signal, and the fifth threshold is a judgment threshold of the suppressive noise jamming of the second window signal;

[0020] According to the first threshold, the second threshold, the third threshold, the fourth threshold and the fifth threshold, a statistical decision tree is constructed, wherein when the local equivalent jam-to-noise ratio is greater than the first threshold, it is determined that there is a jamming signal; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the first window signal is greater than the second threshold, it is determined that the interference type corresponding to the first window signal is false target jamming; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the first window signal is less than the third threshold, it is determined that the interference type corresponding to the first window signal is suppressive noise jamming; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the first window signal is located in the interval [third threshold, second threshold], it is determined that the interference type corresponding to the first window signal is intermittent sampling and forwarding jamming; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the second window signal is greater than the fourth threshold, it is determined that the interference type corresponding to the second window signal is false target jamming; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the second window signal is less than the fifth threshold, it is determined that the interference type corresponding to the second window signal is suppressive noise jamming; when the sliding correlation coefficient peak value of the jamming signal and the transmitted signal of the second window signal is located in the interval [fifth threshold, fourth threshold], it is determined that the interference type corresponding to the second window signal is intermittent sampling and forwarding jamming.

[0021] In an embodiment of the present application, the step 4 comprises:

[0022] The time domain amplitude peak value of the to-be-tested radar active jamming signal is determined, and a signal with a window length of 2M is taken with the time domain amplitude peak value as the center to obtain a corresponding first window signal, wherein M is the length of the transmitted signal;

[0023] After the first window signal is removed from the to-be-tested radar active jamming signal, a corresponding second window signal is obtained;

[0024] The local equivalent jam-to-noise ratio of the first window signal and the peak value of the sliding correlation coefficient of the jamming signal and the transmitting signal, and the local equivalent jam-to-noise ratio of the second window signal and the peak value of the sliding correlation coefficient of the jamming signal and the transmitting signal are respectively calculated; wherein the sliding window length is the length M of the transmitting signal, and the sliding window interval is 1;

[0025] According to the statistical decision tree, the first window signal and the second window signal of the to-be-tested radar active jamming signal are respectively judged to determine the jamming type of the to-be-tested radar active jamming signal; wherein,

[0026] If it is determined that the first window signal does not exist jamming signal, the to-be-tested radar active jamming signal does not exist jamming signal, and only exists noise signal; if it is determined that the first window signal exists jamming signal, and the second window signal does not exist jamming signal, the to-be-tested radar active jamming signal is single-type jamming, and the jamming type is determined according to the jamming type determination result of the first window signal; if it is determined that the first window signal exists jamming signal, and the second window signal exists jamming signal, the to-be-tested radar active jamming signal is composite-type jamming, and the jamming type is determined according to the jamming type determination results of the first window signal and the second window signal.

[0027] In an embodiment of the present application, when it is determined that the to-be-tested radar active jamming signal exists the noise jamming type of suppression, the type of the noise of suppression is further identified by using a wideband radar reconnaissance structure, and the noise amplitude aiming jamming and the noise frequency blocking jamming two types of noise jamming of suppression are distinguished according to the bandwidth size of the signal.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] The radar active composite jamming type identification method of the present application effectively realizes the identification of the radar commonly used active composite jamming signal by analyzing the characteristics of different types of jamming signals, selecting the characteristic parameters such as the local equivalent jam-to-noise ratio and the peak value of the correlation coefficient of the jamming signal and the transmitting signal, and setting the threshold reasonably according to the characteristic parameter value difference of different jamming signals, and constructing a statistical decision tree, which is suitable for the jamming identification occasion in a complex electromagnetic environment.

[0030] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail, and the accompanying drawings are as follows. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a flow chart of a radar active composite jamming type identification method provided by an embodiment of the present application;

[0032] Figure 2 is a time domain waveform and a spectrum diagram of noise amplitude modulation aiming jamming provided by an embodiment of the present application;

[0033] Figure 3 is a time-frequency diagram of noise amplitude modulation aiming jamming provided by an embodiment of the present application;

[0034] Figure 4 is a time domain waveform and a spectrum diagram of noise frequency modulation blocking jamming provided by an embodiment of the present application;

[0035] Figure 5 is a time-frequency diagram of noise frequency modulation blocking jamming provided by an embodiment of the present application;

[0036] Figure 6 is a time domain waveform and a spectrum diagram of false target jamming provided by an embodiment of the present application;

[0037] Figure 7 is a time-frequency diagram of false target jamming provided by an embodiment of the present application;

[0038] Figure 8 is a time domain waveform and a spectrum diagram of intermittent sampling and forwarding jamming provided by an embodiment of the present application;

[0039] Figure 9 is a time-frequency diagram of intermittent sampling and forwarding jamming provided by an embodiment of the present application;

[0040] Figure 10 is a time domain waveform and a spectrum diagram of suppressive noise jamming-false target jamming provided by an embodiment of the present application;

[0041] Figure 11 is a time-frequency diagram of suppressive noise jamming-false target jamming provided by an embodiment of the present application;

[0042] Figure 12 is a time domain waveform and a spectrum diagram of suppressive noise jamming-intermittent sampling and forwarding jamming provided by an embodiment of the present application;

[0043] Figure 13 is a time-frequency diagram of suppressive noise jamming-intermittent sampling and forwarding jamming provided by an embodiment of the present application;

[0044] Figures 14-17 is a calculation result diagram of four characteristic parameters of six types of signals changing with JNR provided by an embodiment of the present application;

[0045] Figure 18is a statistical decision tree schematic diagram provided by an embodiment of the present application;

[0046] Figure 19 is a correct recognition rate curve of various signals changing with JNR provided by an embodiment of the present application.

[0047] Figure 20 is a radar wideband intercept structure prototype schematic diagram for identifying blocking interference and aiming interference provided by an embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, a radar active composite jamming type identification method according to the present application is described in detail below in combination with the drawings and specific embodiments.

[0049] The foregoing and other technical contents, features and effects of the present application can be clearly presented in the following detailed description of specific embodiments in combination with the drawings. Through the description of the specific embodiments, the technical means and effects taken by the present application to achieve the predetermined purposes can be more deeply and specifically understood. However, the attached drawings are provided for reference and illustration only, and are not used to limit the technical solutions of the present application.

[0050] Embodiment One

[0051] Please refer to Figure 1 , Figure 1 is a flowchart of a radar active composite jamming type identification method provided by an embodiment of the present application, as shown in the figure, the radar active composite jamming type identification method of the present embodiment includes:

[0052] Step 1: Construct a radar active jamming database, which contains radar active jamming signals of multiple jamming types including suppression jamming, deception jamming and suppression-deception composite jamming.

[0053] In an optional embodiment, multiple radar active jamming signals are generated by simulation, and each radar active jamming signal is labeled with a corresponding jamming type label.

[0054] Among them, the radar transmitting signal is a linear frequency modulated (LFM) signal, and the jamming types include two categories of suppression jamming and deception jamming.

[0055] In this embodiment, the simulated active radar jamming signals include: active radar jamming signals of two types of suppression noise jamming, namely amplitude-modulated noise targeting jamming and frequency-modulated noise blocking jamming; active radar jamming signals of two types of deception jamming, namely false target jamming and intermittent sampling and forwarding jamming; and active radar jamming signals of two types of composite jamming, namely suppression noise jamming-false target jamming and suppression noise jamming-intermittent sampling and forwarding jamming.

[0056] Furthermore, the simulation process for the interference signal will be explained. First, the radar transmitted signal model can be written. For the radar transmitted linear frequency modulated (LFM) signal, its expression is:

[0057]

[0058] In the formula, k = B / T is the frequency modulation slope of the LFM signal, representing the degree of frequency change, T is the pulse width of the LFM signal, B is the bandwidth of the LFM signal, and f0 is the center frequency. The rectangle function is expressed as follows:

[0059]

[0060] Then, based on the radar-transmitted LFM signal, commonly used radar active jamming signals are simulated and generated. The mathematical models are as follows:

[0061] The expression for noise amplitude modulation (AM) targeting interference is:

[0062]

[0063] In the formula, U0 is the carrier voltage, f j The center frequency is constant, and the modulation noise U is constant. n (t) represents a mean of 0 and a variance of . A generalized stationary random process, The phase is uniformly distributed in [0, 2π] and is related to U. n (t) are mutually independent random variables.

[0064] Targeting the jamming carrier frequency f j Bandwidth Δf j The center frequency f0 and bandwidth Δf of the radar transmitted signal r satisfy,

[0065]

[0066] The expression for frequency-modulated blocking noise interference is:

[0067]

[0068] In the formula, U jf is the amplitude value of the frequency modulation noise interference. j For the noise-modulated interference carrier frequency, K FM Let be the frequency modulation slope, and let the modulation noise u(t) follow a frequency modulation slope. Gaussian distribution, phase It follows a uniform distribution in the range [0, 2π] and is independent of the modulation noise u(t). The effective frequency modulation index is defined as... Δf n The bandwidth of the modulation noise is represented when m fe When the value is ≥1, the noise frequency modulation interference is a blocking interference; otherwise, it is a targeted interference.

[0069] carrier frequency f of blocking interference j Bandwidth Δf j The center frequency f0 and bandwidth Δf of the radar transmitted signal r satisfy

[0070]

[0071] The expression for false target interference is:

[0072]

[0073] Among them, S J (t) is the signal of a single dummy target, a i τ represents the amplitude of the i-th false target signal. i φ represents the time delay of the i-th false target signal. i Let n represent the phase of the signal of the i-th false target, and n represent the false target.

[0074] The mathematical model expression for Intermittent Sample Repeat Forwarding Interference (ISRJ) is as follows:

[0075]

[0076] In the formula, M and N are the number of pulse segments and the number of forwards, respectively, representing the intermittently sampled signal. T1 represents the pulse width of p(t), T s denoted as the pulse repetition period, and k as the frequency modulation slope of the linear frequency modulated signal transmitted by the radar.

[0077] The expression for composite interference is:

[0078] J(t)=a1·J1(t-τ1)+a2·J2(t-τ2) (9);

[0079] In the formula, J1(t) represents suppressed noise interference, a1 represents its amplitude, τ1 represents its time delay, J2(t) represents false target interference or intermittent sampling and repeated forwarding interference, a2 represents its amplitude, and τ2 represents its time delay.

[0080] Then, based on the above signal model, Gaussian white noise is added to the interference signal to construct six types of radar active jamming signals, including noise amplitude modulation homing jamming, noise frequency modulation barrage jamming, false target jamming, intermittent sampling retransmission jamming, suppressive noise jamming + false target jamming, and suppressive noise jamming + intermittent sampling retransmission jamming, with different jammer-to-noise ratios, to form a radar active jamming database.

[0081] Step 2: Feature analysis and extraction are performed on all radar active jamming signals in the radar active jamming database to obtain corresponding feature parameters, and the feature parameter library of the radar active jamming signal is constructed using the feature parameters.

[0082] In this embodiment, the feature parameters include a local equivalent jammer-to-noise ratio and a sliding correlation coefficient peak value of the interference signal and the transmitted signal.

[0083] In an optional implementation, step 2 includes:

[0084] Step 2.1: The time-domain amplitude peak value of the radar active jamming signal is determined, a signal with a window length of 2M is taken with the time-domain amplitude peak value as the center to obtain a first window signal, where M is the length of the transmitted signal.

[0085] Step 2.2: The ratio of the signal amplitude mean value to the noise mean value of the first window signal is calculated to obtain the local equivalent jammer-to-noise ratio of the first window signal, and the sliding correlation coefficient peak value of the interference signal and the transmitted signal corresponding to the first window signal is calculated, where the sliding window length is the length M of the transmitted signal and the sliding window interval is 1.

[0086] Step 2.3: For the radar active jamming signal of the composite jamming type, the second window signal is obtained after removing the first window signal from the radar active jamming signal.

[0087] Step 2.4: The ratio of the signal amplitude mean value to the noise mean value of the second window signal is calculated to obtain the local equivalent jammer-to-noise ratio of the second window signal, and the sliding correlation coefficient peak value of the interference signal and the transmitted signal corresponding to the second window signal is calculated.

[0088] Step 2.5: According to the interference type label corresponding to all radar active jamming signals, the local equivalent jammer-to-noise ratio and the sliding correlation coefficient peak value of the interference signal and the transmitted signal corresponding to the first window signal, and the local equivalent jammer-to-noise ratio and the sliding correlation coefficient peak value of the interference signal and the transmitted signal corresponding to the second window signal, the feature parameter library is constructed.

[0089] In this embodiment, the calculation of the correlation coefficient according to formula (10) is as follows:

[0090]

[0091] wherein X, Y are two signals for which the correlation is sought, is the signal mean, |p X,Y The closer to 1, the stronger the correlation.

[0092] Step 3: statistically analyzing the feature parameters in the feature parameter library to determine the feature parameter threshold value for the interference signal classification, and constructing a statistical decision tree according to the feature parameter threshold value;

[0093] In an optional embodiment, step 3 comprises:

[0094] Step 3.1: statistically analyzing and plotting the interference type corresponding to the radar active interference signal and the corresponding feature parameters to determine a first threshold, a second threshold, a third threshold, a fourth threshold, and a fifth threshold.

[0095] In this embodiment, the first threshold is the judgment threshold of the interference signal, the second threshold is the judgment threshold of the false target interference of the first window signal, the third threshold is the judgment threshold of the suppressive noise interference of the first window signal, the fourth threshold is the judgment threshold of the false target interference of the second window signal, and the fifth threshold is the judgment threshold of the suppressive noise interference of the second window signal.

[0096] Step 3.2: constructing a statistical decision tree according to the first threshold, the second threshold, the third threshold, the fourth threshold, and the fifth threshold.

[0097] In this embodiment, when the local equivalent jamming noise ratio is greater than the first threshold, it is determined that there is an interference signal; when the local equivalent jamming noise ratio of the first window signal and the local equivalent jamming noise ratio of the second window signal are both greater than the first threshold, it is determined that there is a composite type of interference signal; and when only the local equivalent jamming noise ratio of the first window signal is greater than the first threshold, it is determined that there is a single type of interference signal.

[0098] When the sliding correlation coefficient peak value of the interference signal of the first window signal and the transmitted signal is greater than the second threshold, it is determined that the interference type corresponding to the first window signal is false target interference; when the sliding correlation coefficient peak value of the interference signal of the first window signal and the transmitted signal is less than the third threshold, it is determined that the interference type corresponding to the first window signal is suppressive noise interference; and when the sliding correlation coefficient peak value of the interference signal of the first window signal and the transmitted signal is located in the interval [third threshold, second threshold] (the third threshold is less than the second threshold), it is determined that the interference type corresponding to the first window signal is intermittent sampling and retransmission interference.

[0099] When the peak value of the sliding correlation coefficient of the interference signal and the transmit signal of the second window signal is greater than a fourth threshold, it is determined that the interference type corresponding to the second window signal is false target interference; when the peak value of the sliding correlation coefficient of the interference signal and the transmit signal of the second window signal is less than a fifth threshold, it is determined that the interference type corresponding to the second window signal is suppressive noise interference; and when the peak value of the sliding correlation coefficient of the interference signal and the transmit signal of the second window signal is within an interval [the fifth threshold, the fourth threshold] (the fifth threshold is less than the fourth threshold), it is determined that the interference type corresponding to the second window signal is intermittent sampling and forwarding interference.

[0100] Step 4: The interference type of the to-be-tested radar active jamming signal is identified by using a statistical decision tree.

[0101] In an optional implementation, step 4 includes:

[0102] Step 4.1: The time-domain amplitude peak value of the to-be-tested radar active jamming signal is determined, a signal with a window length of 2M is taken with the time-domain amplitude peak value as the center, and a corresponding first window signal is obtained, where M is the length of the transmit signal.

[0103] Step 4.2: After the first window signal is removed from the to-be-tested radar active jamming signal, a corresponding second window signal is obtained.

[0104] Step 4.3: The local equivalent jam-to-noise ratio of the first window signal and the peak value of the sliding correlation coefficient of the interference signal and the transmit signal are calculated, and the local equivalent jam-to-noise ratio of the second window signal and the peak value of the sliding correlation coefficient of the interference signal and the transmit signal are calculated; where the sliding window length is the length M of the transmit signal, and the sliding window interval is 1.

[0105] In this embodiment, the local equivalent jam-to-noise ratio of the first window signal is denoted as JNR1, the peak value of the sliding correlation coefficient of the interference signal and the transmit signal corresponding to the first window signal is denoted as Corr1, the local equivalent jam-to-noise ratio of the second window signal is denoted as JNR2, and the peak value of the sliding correlation coefficient of the interference signal and the transmit signal corresponding to the second window signal is denoted as Corr2.

[0106] Step 4.4: According to the statistical decision tree, the first window signal and the second window signal of the to-be-tested radar active jamming signal are respectively judged, and the interference type of the to-be-tested radar active jamming signal is determined.

[0107] In the embodiment, if it is determined that the first window signal does not have the interference signal, the to-be-tested radar active jamming signal does not have the interference signal and only has the noise signal; if it is determined that the first window signal has the interference signal and the second window signal does not have the interference signal, the to-be-tested radar active jamming signal is a single-type jamming, and the jamming type is determined according to the determination result of the jamming type of the first window signal; if it is determined that the first window signal has the interference signal and the second window signal has the interference signal, the to-be-tested radar active jamming signal is a composite-type jamming, and the jamming type is determined according to the determination results of the jamming types of the first window signal and the second window signal.

[0108] Specifically, when JNR1 is greater than the first threshold, it is determined that the interference signal exists, otherwise it is considered that the to-be-tested radar active jamming signal does not have the interference signal and only has the noise signal.

[0109] After it is determined that the first window signal has the interference signal, it is judged whether JNR2 is greater than the first threshold, when JNR2 is greater than the first threshold, it is determined that the to-be-tested radar active jamming signal is a composite-type jamming, otherwise it is determined that the to-be-tested radar active jamming signal is a single-type jamming.

[0110] After it is determined that the to-be-tested radar active jamming signal is a single-type jamming, the jamming type of the first window signal is discriminated, when Corr1 is greater than the second threshold, it is determined that the jamming type of the to-be-tested radar active jamming signal is false target jamming; when Corr1 is less than the third threshold, it is determined that the jamming type of the to-be-tested radar active jamming signal is suppressive noise jamming; when Corr1 is in the interval of [the third threshold, the second threshold], it is determined that the jamming type of the to-be-tested radar active jamming signal is intermittent sampling and retransmission jamming.

[0111] After it is determined that the to-be-tested radar active jamming signal is a composite-type jamming, the jamming types of the first window signal and the second window signal are discriminated respectively, the discrimination manner of the jamming type of the first window signal is the same as that of the single-type jamming, which will not be repeated here, and the discrimination manner of the jamming type of the second window signal is similar to that of the first window signal, when Corr2 is greater than the fourth threshold, it is determined that the jamming type of the second window signal is false target jamming; when Corr2 is less than the fifth threshold, it is determined that the jamming type of the second window signal is suppressive noise jamming; when Corr2 is in the interval of [the fifth threshold, the fourth threshold], it is determined that the jamming type of the second window signal is intermittent sampling and retransmission jamming. Finally, the jamming type of the to-be-tested radar active jamming signal is determined according to the determination results of the jamming types of the first window signal and the second window signal.

[0112] Further, when it is determined that the to-be-tested radar active jamming signal is of the suppressive noise jamming type, the type of the suppressive noise can be further identified by using a wideband radar reconnaissance structure, and the noise amplitude aiming jamming and the noise frequency blocking jamming two types of suppressive noise jamming types are distinguished according to the bandwidth of the signal, wherein the bandwidth of the noise frequency blocking jamming is larger, and the bandwidth of the noise amplitude aiming jamming is smaller.

[0113] The radar active composite jamming type identification method of the embodiment of the present application can effectively realize the identification of the radar commonly used active composite jamming signal by analyzing the characteristics of different types of jamming signals, selecting the partial equivalent jamming noise ratio, the correlation coefficient peak value of the jamming signal and the transmitted signal and other characteristic parameters with separability to construct a characteristic parameter library, and reasonably setting the threshold according to the characteristic parameter value difference of different jamming signals to construct a statistical decision tree, and is suitable for the jamming identification occasion in a complex electromagnetic environment.

[0114] Embodiment two

[0115] The embodiment further verifies and illustrates the identification effect of the radar active composite jamming type identification method of embodiment one through a simulation experiment.

[0116] 1. Simulation conditions

[0117] The hardware platform of the simulation experiment of the embodiment is: Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz frequency is 1.99GHz.

[0118] The software of the simulation experiment of the embodiment uses MATLAB R2021a.

[0119] The embodiment selects a linear frequency modulation signal as the transmitted signal of the radar, sets-10dB, -8dB, -6dB, -4dB, -2dB, 0dB, 2dB, 4dB, 6dB, 8dB, 10dB, 12dB, 14dB, 16dB, 18dB, 20dB 16 different jamming noise ratios (Jamming Noise Ratio, JNR), and generates six types of composite jamming signals composed of noise amplitude aiming jamming, noise frequency blocking jamming, false target jamming, intermittent sampling and forwarding jamming, suppressive noise jamming + false target jamming, and suppressive noise jamming + intermittent sampling and forwarding jamming. Specifically, the radar transmitted signal simulation parameters are shown in Table 1, and the main simulation parameters of each type of jamming signal are shown in Table 2:

[0120] Table 1 Transmitted signal simulation parameter table

[0121] Parameter Value Signal time width 20 μs Signal bandwidth 20 MHz Signal sampling rate 80 MHz

[0122] Table 2 Jamming signal simulation parameter table

[0123]

[0124] 2. Simulation content and result analysis

[0125] Considering that the radar transmits a linear frequency modulation signal, four commonly used radar active jamming signals are simulated to generate six types of signals to be distinguished, Figures 2-13 The time domain waveform, spectrum diagram and time-frequency diagram of noise amplitude modulation aiming jamming, noise frequency modulation blocking jamming, false target jamming, intermittent sampling retransmission jamming, suppressive noise jamming+false target jamming and suppressive noise jamming+intermittent sampling retransmission jamming are observed, and different signal characteristics are found.

[0126] Then, the characteristics of different signals are quantified by using a feature extraction method, and the distinguishing degree is found, Figure 14 The first window signal equivalent jam-to-noise ratio (JNR) change curve with JNR can be used to determine whether the jamming exists, Figure 15 The first window signal sliding correlation coefficient peak value change curve with JNR, Figure 16 The second window signal equivalent jam-to-noise ratio (JNR) change curve with JNR, Figure 17 The second window signal sliding correlation coefficient peak value change curve with JNR.

[0127] The generation mechanism of different jamming signals can further verify the rationality of the characteristic parameter values. For the correlation coefficient, the false target jamming is the jammer transmitting a false target signal similar to the transmitted signal to the opponent radar, so the correlation with the transmitted signal is the strongest. The intermittent sampling retransmission jamming is generated by using the digital radio frequency memory (DRFM) technology to slice and retransmit the transmitted signal. Since it is an incomplete fragment of the transmitted signal, it has a certain correlation with the transmitted signal, but the correlation is weaker than that of the false target signal. The suppressive noise jamming is generated by Gaussian white noise modulation, and has nothing to do with the transmitted signal, so the correlation between them is the weakest. According to this, the three types of jamming can be identified.

[0128] According to the above method, four characteristic parameters JNR1, JNR2, Corr1 and Corr2 are extracted, and according to the difference of the characteristic parameter values of different jamming signals, the thresholds are reasonably set, and a statistical decision tree as Figure 18 is constructed to identify the type of the jamming signal, and Figure 19 the identification accuracy can be known. When the jam-to-noise ratio is low, the identification rate is low due to the influence of Gaussian noise. With the increase of the jam-to-noise ratio, the identification rate is improved. When the jam-to-noise ratio is greater than 0 dB, the identification rate of each type of jamming signal can reach 100%, which verifies the effectiveness and feasibility of the present application.

[0129] In addition, the above-mentioned rough classification of both the blocking jamming and the aiming jamming as the suppressing noise jamming, for further identification of the suppressing noise, a wideband radar reconnaissance structure is adopted to realize, and a prototype structure diagram thereof is shown as Figure 20 The two are distinguished according to the different bandwidths.

[0130] It should be noted that, in this article, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants are intended to cover non-exclusive inclusion, so that the article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the article or device including the element. The similar words such as "connected" or "connected" are not limited to physical or mechanical connection, but can include electrical connection, whether direct or indirect.

[0131] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific implementation of the present application cannot be limited to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the concept of the present application, and all of them should be regarded as falling within the protection scope of the present application.

Claims

1. A radar active composite jamming type identification method, characterized in that, The method comprises the following steps: Step 1: constructing a radar active jamming database, wherein the radar active jamming database comprises radar active jamming signals of multiple jamming types including suppressive jamming, deceptive jamming and suppressive-deceptive composite jamming; Step 2: performing feature analysis and extraction on all radar active jamming signals in the radar active jamming database to obtain corresponding feature parameters, and constructing a feature parameter library of radar active jamming signals by using the feature parameters; wherein the feature parameters comprise local equivalent jam-to-noise ratio and peak value of sliding correlation coefficient of the jamming signal and the transmitted signal; the step 2 comprises: Step 2.1: determining the time-domain amplitude peak value of the radar active jamming signal, taking a signal with a window length of 2M centered on the time-domain amplitude peak value to obtain a first window signal, wherein M is the length of the transmitted signal; Step 2.2: calculating the ratio of the signal amplitude mean value to the noise mean value of the first window signal to obtain the local equivalent jam-to-noise ratio of the first window signal, and calculating the peak value of the sliding correlation coefficient of the jamming signal and the transmitted signal corresponding to the first window signal, wherein the sliding window length is the length M of the transmitted signal and the sliding window interval is 1; Step 2.3: for the radar active jamming signal of the composite jamming type, removing the first window signal from the radar active jamming signal to obtain a second window signal; Step 2.4: calculating the ratio of the signal amplitude mean value to the noise mean value of the second window signal to obtain the local equivalent jam-to-noise ratio of the second window signal, and calculating the peak value of the sliding correlation coefficient of the jamming signal and the transmitted signal corresponding to the second window signal; Step 2.5: constructing the feature parameter library according to the jamming type labels corresponding to all radar active jamming signals, the local equivalent jam-to-noise ratio and the peak value of the sliding correlation coefficient of the jamming signal and the transmitted signal corresponding to the first window signal, and the local equivalent jam-to-noise ratio and the peak value of the sliding correlation coefficient of the jamming signal and the transmitted signal corresponding to the second window signal; Step 3: performing statistical analysis on the feature parameters of the feature parameter library to determine the feature parameter threshold value of the jamming signal classification, and constructing a statistical decision tree according to the feature parameter threshold value; Step 4: using the statistical decision tree to realize the jamming type identification of the to-be-tested radar active jamming signal.

2. The radar active composite jamming type identification method according to claim 1, characterized in that, The step 1 comprises: using simulation to generate multiple radar active jamming signals, and labeling the corresponding jamming type label for each radar active jamming signal; wherein the multiple radar active jamming signals comprise radar active jamming signals of two kinds of suppressive noise jamming, i.e., noise amplitude modulation aiming jamming and noise frequency modulation blocking jamming, radar active jamming signals of two kinds of deceptive jamming, i.e., false target jamming and intermittent sampling retransmission jamming, and radar active jamming signals of two kinds of composite jamming, i.e., suppressive noise jamming-false target jamming and suppressive noise jamming-intermittent sampling retransmission jamming.

3. The radar active composite jamming type identification method according to claim 2, characterized in that, The step 3 comprises: The interference type corresponding to the radar active interference signal and the corresponding characteristic parameter are statistically plotted and analyzed to determine a first threshold, a second threshold, a third threshold, a fourth threshold and a fifth threshold; wherein the first threshold is a judgment threshold of the interference signal, the second threshold is a judgment threshold of the false target interference of the first window signal, the third threshold is a judgment threshold of the suppressing noise interference of the first window signal, the fourth threshold is a judgment threshold of the false target interference of the second window signal, and the fifth threshold is a judgment threshold of the suppressing noise interference of the second window signal; According to the first threshold, the second threshold, the third threshold, the fourth threshold and the fifth threshold, a statistical decision tree is constructed, wherein when the local equivalent jamming noise ratio is greater than the first threshold, it is determined that there is an interference signal; when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the first window signal is greater than the second threshold, it is determined that the interference type corresponding to the first window signal is false target interference; when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the first window signal is less than the third threshold, it is determined that the interference type corresponding to the first window signal is suppressing noise interference; when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the first window signal is located in the interval [third threshold, second threshold], it is determined that the interference type corresponding to the first window signal is intermittent sampling and forwarding interference; when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the second window signal is greater than the fourth threshold, it is determined that the interference type corresponding to the second window signal is false target interference; when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the second window signal is less than the fifth threshold, it is determined that the interference type corresponding to the second window signal is suppressing noise interference; and when the sliding correlation coefficient peak value of the interference signal and the transmission signal of the second window signal is located in the interval [fifth threshold, fourth threshold], it is determined that the interference type corresponding to the second window signal is intermittent sampling and forwarding interference.

4. The radar active composite jamming type identification method according to claim 3, characterized in that, The step 4 comprises: The time domain amplitude peak value of the to-be-tested radar active interference signal is determined, and a signal with a window length of 2M is taken with the time domain amplitude peak value as the center to obtain a corresponding first window signal, wherein M is the length of the transmission signal; After removing the first window signal from the to-be-tested radar active interference signal, a corresponding second window signal is obtained; The local equivalent jamming noise ratio of the first window signal and the sliding correlation coefficient peak value of the interference signal and the transmission signal, and the local equivalent jamming noise ratio of the second window signal and the sliding correlation coefficient peak value of the interference signal and the transmission signal are calculated respectively; wherein the sliding window length is the transmission signal length M, and the sliding window interval is 1; According to the statistical decision tree, the first window signal and the second window signal of the to-be-tested radar active interference signal are judged respectively to determine the interference type of the to-be-tested radar active interference signal; wherein If it is determined that the first window signal does not have the jamming signal, the to-be-tested radar active jamming signal does not have the jamming signal and only has a noise signal; if it is determined that the first window signal has the jamming signal and the second window signal does not have the jamming signal, the to-be-tested radar active jamming signal is a single-type jamming, and the jamming type is determined according to the determination result of the jamming type of the first window signal; if it is determined that the first window signal has the jamming signal and the second window signal has the jamming signal, the to-be-tested radar active jamming signal is a composite-type jamming, and the jamming type is determined according to the determination results of the jamming types of the first window signal and the second window signal.

5. The radar active composite jamming type identification method according to claim 4, characterized in that, When it is determined that the to-be-tested radar active jamming signal has the suppressive noise jamming type, the type of the suppressive noise is further identified by using a wideband radar reconnaissance structure, and the noise amplitude aiming jamming and the noise frequency blocking jamming are distinguished according to the bandwidth size of the signal.

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