A complex waveform design method against active jamming

Abstract

The present application relates to a kind of complex waveform design methods of anti-active jamming, belong to radar detection guidance and electronic countermeasure technical field, solve the problem that the existing radar main signal is higher in the probability of being detected and intercepted by jammer.One kind of complex waveform design methods of anti-active jamming, including the following steps: complex waveform signal number design;Complex waveform time domain design is carried out;Design the frequency domain parameter of main signal and cover signal.The present application proposes that in the jamming countermeasure environment, radar is launched complex waveform after power-on, main signal and cover signal are randomly arranged, cover signal generation time, pulse width, signal bandwidth, emission frequency point, frequency modulation slope and signal number are random, difficult to predict.Complex waveform design makes radar emission signal more difficult to distinguish, greatly reduces the probability of main signal being intercepted by jammer and the difficulty of correct implementation of interference, increases the means and strategy of anti-jamming, improves the performance of radar anti-jamming and radar tracking stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the radar detection guidance and electronic countermeasure technical field, and particularly relates to a complex waveform design method against active jamming. BACKGROUND

[0002] With the development of military electronic technology, the application of various active jammers is increasing, and at present, since the radar only transmits a single main signal or has a single cover signal (such as shown in the figure), the probability of the radar main signal being detected and intercepted by the jammer is relatively high. Figures 1-2 In order to increase the difficulty of the radar main signal being intercepted and improve the radar's ability to resist active jamming, complex waveform design is needed for the radar transmitted signal. SUMMARY

[0003] In view of the above analysis, the present application aims to provide a complex waveform design method against active jamming to solve the problem that the existing radar main signal is detected and intercepted by the jammer with a relatively high probability.

[0004] The purpose of the present application is mainly realized through the following technical solutions:

[0005] A complex waveform design method against active jamming, comprising the following steps:

[0006] Step 1, complex waveform signal number design;

[0007] Step 2, complex waveform time domain design according to the complex waveform signal number designed in step 1;

[0008] Step 3, design of the frequency domain parameters of the main signal and the cover signal;

[0009] Step 4, transmitting the complex waveform designed in steps 1-3 in the same synchronization period;

[0010] Step 5, judging whether the radar main signal is intercepted and interfered, if so, changing the arrangement form of the cover signal and the main signal, repeating steps 1-5 until the interference is eliminated.

[0011] Further, in step 1, the complex waveform against active jamming is composed of a main signal and n cover signals i, the main signal is unique, and the number n of cover signals is at least 2.

[0012] Further, in step 2, the time domain design includes the design of the main signal and cover signal amplitude, signal generation time, and signal pulse width.

[0013] Further, in step 2, the amplitude of each cover signal is greater than or equal to the amplitude of the main signal.

[0014] Further, in step 2, the pulse width of the main signal is greater than the pulse width of the cover signal.

[0015] Further, in step 2, the pulse width of the main signal needs to be greater than or equal to the sum of the pulse widths of all cover signals.

[0016] Further, in step 3, the frequency domain parameter design includes the design of signal frequency, signal bandwidth and frequency modulation slope.

[0017] Further, in step 3, the frequency points of the main signal and the cover signal are inconsistent.

[0018] Further, in step 3, the bandwidth of the main signal is smaller than the bandwidth of the cover signal.

[0019] Further, in step 3, the frequency modulation slope of at least one cover signal and the main signal is not the same.

[0020] The present application can achieve the following beneficial effects:

[0021] (1) The anti-active jamming complex waveform design method of the present application proposes to emit complex waveforms on the radar under the jamming countermeasure environment, the main signal and the cover signal are randomly arranged, the cover signal generation time, pulse width, signal bandwidth, transmission frequency, frequency modulation slope and signal number are random, which is difficult to predict. The complex waveform design makes the radar transmission signal more difficult to distinguish between true and false, greatly reduces the probability of the jammer intercepting the main signal and the difficulty of correctly implementing the jamming, increases the anti-jamming means and strategies, and improves the performance of radar anti-jamming and radar tracking stability.

[0022] The above technical solutions in the present application can also be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or by implementing the present application. The purpose and other advantages of the present application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0024] Figure 1 Time domain schematic diagram for 1 cover waveform design of existing waveform;

[0025] Figure 2 Frequency domain schematic diagram for 1 cover waveform design of existing waveform;

[0026] Figure 3 Time domain schematic diagram for 2 cover waveform design of complex waveform of the present application;

[0027] Figure 4 The figure shows the design of the main wave shape in the middle frequency domain of the two cover wave shapes of the complex wave shape of the embodiment of the present application;

[0028] Figure 5 The figure shows the design of the main wave shape in the front time domain of the two cover wave shapes of the complex wave shape of the embodiment of the present application;

[0029] Figure 6 The figure shows the design of the main wave shape in the front frequency domain of the two cover wave shapes of the complex wave shape of the embodiment of the present application;

[0030] Figure 7 The figure shows the design of the main wave shape in the back time domain of the two cover wave shapes of the complex wave shape of the embodiment of the present application;

[0031] Figure 8 The figure shows the design of the main wave shape in the back frequency domain of the two cover wave shapes of the complex wave shape of the embodiment of the present application. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of the present application and are used to explain the principles of the embodiments of the present application, but are not used to limit the scope of the present application.

[0033] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be fixedly connected, or detachably connected, or integrally connected, it can be mechanically connected, or electrically connected, it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above-mentioned term in the present application can be understood according to the specific circumstances.

[0034] The terms "top", "bottom", "above", "under" and "on" used throughout the description are relative positions of the components of the device, for example, the relative positions of the top and bottom substrates inside the device. It can be understood that the device is multifunctional, regardless of their orientation in space.

[0035] One embodiment of the present application, as shown in Figures 3 to 8 discloses a complex wave shape design method against active jamming, comprising the following steps:

[0036] Step 1, complex wave shape signal number design:

[0037] In this embodiment, the complex waveform against active jamming is composed of a main signal and n cover signals i, the main signal is unique, and the number of cover signals n is at least two, i.e. i = 2, …, n. The main signal and the cover signals are randomly arranged, and the more the number of selected cover signals, the better the cover effect on the main signal.

[0038] The number of cover signals also needs to consider the duty cycle of the overall signal. The duty cycle refers to the ratio of the duration of a positive pulse in a pulse sequence (such as a square wave) to the total period of the pulse.

[0039] Assume that the pulse width of the main signal is τ0, the pulse width of the cover signal i is τi, and the period of the radar synchronization signal pulse is T. Then the duty cycle D is: i c

[0040]

[0041] Due to the power limitation of the transmitter, the duty cycle of the missile-borne radar is usually selected between 20% and 30%. Under the condition of meeting the duty cycle, as many cover signals as possible are selected to determine the number of cover signals, and the pulse width τi of each cover signal can be designed to be unequal. i

[0042] Step 2, according to the number of complex waveform signals designed in step 1, the time domain design of the complex waveform is performed.

[0043] In this embodiment, the time domain design includes the amplitude, signal generation time, and signal pulse width design of the main signal and cover signals, which specifically includes the following steps:

[0044] Step 2.1, main signal and cover signal amplitude design:

[0045] In a complex electromagnetic environment, the jamming party needs to detect the radar signal before it can purposefully deploy corresponding electromagnetic jamming. The stronger the signal amplitude, the greater the probability of detection by the jammed party. Therefore, in the design, the amplitudes A i of the cover signals are usually greater than or equal to the amplitude A0 of the main signal, i.e. A i ≥ A0, so as to reduce the probability of the jamming party detecting the main signal and effectively protect the main signal.

[0046] Step 2.2, main signal and cover signal generation time design:

[0047] In this embodiment, the delay of the main signal relative to the synchronization pulse is t0, and the delay of the cover signal i relative to the synchronization pulse is t i i. When designing, it is necessary to ensure that the cover signal pulse does not overlap with the main signal pulse to avoid mutual influence between the main signal and the cover signal.

[0048] ​​​Exemplarily, if the number of cover signals is 2, the design is usually that the main signal is in the middle, and one cover signal is in front and one is behind, so that the radar main signal can be better hidden, and the probability of the main signal being detected by the interference party is reduced, while it is necessary to ensure that the cover signal and the main signal do not overlap, as shown in Figure 3

[0049] In order to ensure that the cover signal and the main signal do not overlap, the delay of the main signal and the cover signal relative to the synchronization pulse and the pulse width of the main signal and the cover signal need to meet:

[0050]

[0051] so as to ensure that the waveforms of the main signal and the cover signal are not distorted.

[0052] Further, if it is found in the radar detection process that the radar main signal designed in such a complex waveform is interfered by the interference party, the complex waveform design scheme needs to be adaptively transformed immediately to get rid of the interference of the interference party.

[0053] The transformed complex waveform time domain design scheme includes that the main signal is in front and two cover signals are behind, or two cover signals are in front and the main signal is behind, while it is necessary to ensure that the cover signal and the main signal do not overlap.

[0054] When the design scheme is that the main signal is in front and two cover signals are behind, as shown in Figure 5 , the delay of the main signal and the cover signal relative to the synchronization pulse and the pulse width of the main signal and the cover signal need to meet:

[0055]

[0056] so as to ensure that the waveforms of the main signal and the cover signal are not distorted.

[0057] When the design scheme is that the main signal is behind and two cover signals are in front, as shown in Figure 7 , the delay of the main signal and the cover signal relative to the synchronization pulse and the pulse width of the main signal and the cover signal need to meet:

[0058]

[0059] so as to ensure that the waveforms of the main signal and the cover signal are not distorted.

[0060] When the number of cover signals is greater than 2, the amplitudes, signal generation times and signal pulse widths of the main signal and the cover signals are designed according to the above scheme.

[0061] Step 2.3, main signal and cover signal pulse width design:

[0062] ​In this embodiment, in order to ensure that the energy of the main signal is the strongest, facilitate the reception after the main signal is transmitted, the pulse width of the main signal is greater than the pulse width of the cover signal, and the overall signal meets the technical parameter requirement of the duty cycle.

[0063] Exemplarily, the pulse width design of the main signal and the cover signal follows the following principles:

[0064]

[0065] Wherein, n is the number of cover signals, that is, the pulse width of the main signal needs to be greater than or equal to the sum of the pulse widths of all cover signals.

[0066] Step 3, design the frequency domain parameters of the main signal and the cover signal:

[0067] In this embodiment, the frequency domain parameter design includes the design of signal frequency, signal bandwidth and frequency modulation slope, and specifically includes the following steps:

[0068] Step 3.1, design the signal frequency of the main signal and the cover signal, wherein the signal frequency of the radar transmitted main signal and the cover signal is inconsistent, which facilitates the reception of the main signal.

[0069] In this embodiment, the interval between the frequency of the main signal and the frequency of the cover signal is selected within the entire working bandwidth, for example: the frequency of the main signal is f0, and the frequency of the cover signal i is f i , then f0≠f i , i=1,..., n.

[0070] Step 3.2, design the bandwidth of the main signal and the cover signal, the bandwidth B0 of the main signal is less than the bandwidth B i of the cover signal.

[0071] In a complex electromagnetic environment, the interference party needs to detect the radar signal, and then can purposefully emit corresponding electromagnetic interference, the signal frequency domain bandwidth is wide, and the probability of being detected by the interfered party is greater, so the bandwidth B0 of the main signal is less than the bandwidth B i of the cover signal, thereby effectively reducing the probability of the radar main signal being detected by the interference party, and effectively protecting the main signal.

[0072] In this embodiment, the bandwidth design of the main signal and the cover signal follows the following principles:

[0073]

[0074] That is, the bandwidth B i of the cover signal is at least greater than or equal to 2 times the bandwidth B0 of the main signal, so that the clutter signal entering the receiving channel is less, and the probability of the main signal frequency being detected by the interference party is smaller. The bandwidth of the main signal and the cover signal is selected within the entire working bandwidth, and the signals do not overlap in the frequency domain.

[0075] Exemplarily, if the number of cover signals is 2, the bandwidth of the main signal is B0, and the bandwidth of the cover signal is B i As shown in the complex waveform frequency domain, the following conditions need to be met simultaneously: Figure 4

[0076]

[0077] Thus, it is ensured that the cover signals and the main signal do not overlap in the frequency domain.

[0078] Further, if it is found that the complex waveform designed radar main signal is interfered by the interference party in the radar detection process, the complex waveform design scheme needs to be changed immediately to get rid of the interference of the interference party.

[0079] The changed complex waveform frequency domain design scheme includes the main signal in front of two cover signals, or two cover signals in front of the main signal.

[0080] When the design scheme is the main signal in front of two cover signals, as shown in the complex waveform frequency domain, the following conditions need to be met simultaneously: Figure 6

[0081]

[0082] Thus, it is ensured that the cover signals and the main signal do not overlap in the frequency domain.

[0083] When the design scheme is the main signal in front of two cover signals, as shown in the complex waveform frequency domain, the following conditions need to be met simultaneously: Figure 8

[0084]

[0085] Thus, it is ensured that the cover signals and the main signal do not overlap in the frequency domain.

[0086] When the number of cover signals is greater than 2, the bandwidths of the main signal and the cover signals are designed according to the above scheme.

[0087] Step 3.3, main signal and cover signal frequency modulation slope design.

[0088] In this embodiment, the frequency modulation slopes of the at least one cover signal and the main signal are different, so as to enhance the anti-interference effect of the cover signal.

[0089] The radar linear frequency modulation signal s(t) is represented as:

[0090]

[0091] ​​​Wherein, t0 is the time delay of radar signal relative to the synchronization pulse,

[0092] τ is the pulse width,

[0093] f0 is the carrier frequency point of radar signal,

[0094] k is the frequency modulation slope of radar signal, when k>0, it is called positive frequency modulation slope, and when k<0, it is called negative frequency modulation slope.

[0095] Exemplarily, when the number of cover signals is 2, the design scheme includes that the main signal is a positive frequency modulation slope, and the two cover signals are negative frequency modulation slopes; or the main signal is a negative frequency modulation slope, and the two cover signals are positive frequency modulation slopes; or the main signal and one of the cover signals are positive frequency modulation slopes, and the other cover signal is a negative frequency modulation slope; or the main signal and one of the cover signals are negative frequency modulation slopes, and the other cover signal is a positive frequency modulation slope.

[0096] When the number of cover signals is greater than 2, the frequency modulation slopes of the main signal and the cover signals are designed according to the above scheme.

[0097] Step 4, the complex waveform designed in steps 1-3 is transmitted in the same synchronization cycle.

[0098] Step 5, it is judged whether the radar main signal is intercepted and interfered, if yes, the arrangement form of the cover signal and the main signal is changed, and steps 1-5 are repeated until the interference of the interference party is eliminated.

[0099] It is judged whether the radar main signal is intercepted and interfered, if the radar tracking is stable, it is determined that it is not interfered, which indicates that the complex waveform design is effective, the active jamming resistance is successful, and the transmission of the complex waveform is continued unchanged. If the radar target is lost, and the loss is continuous for a certain time, it is determined that it is interfered by the enemy party, the arrangement form of the cover signal and the main signal is changed, and steps 1-5 are repeated until the interference of the interference party is eliminated.

[0100] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any change or replacement easily thought by the person skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application.

Claims

1. A method for complex waveform design against active jamming, characterized in that, The method comprises the following steps: Step 1, the number of complex waveform signal design; the pulse width of the main signal is τ0, the pulse width of the cover signal i is τi i , the period of the radar synchronization signal pulse is T, and the duty cycle D c is: Under the condition of meeting the duty cycle, the number of cover signals is selected as much as possible; the main signal is unique, and the number of cover signals n is at least 2; Step 2, according to the number of complex waveform signals designed in step 1, complex waveform time domain design is carried out; the amplitude of each cover signal is greater than or equal to the amplitude of the main signal; when the main signal is in the middle, one cover signal before and after the main signal, it satisfies: When the main signal is in front, two cover signals behind the main signal, it satisfies: When the main signal is behind, two cover signals in front of the main signal, it satisfies: Wherein, t0, t1, t2 are the time delay of the main signal, cover signal 1 and cover signal 2 relative to the synchronization pulse respectively, τ0, τ1, τ2 are the pulse width of the main signal, cover signal 1 and cover signal 2 respectively; the pulse width of the main signal is greater than or equal to the sum of the pulse widths of all cover signals. Step 3, design the frequency domain parameters of the main signal and the cover signal; the frequency points of the main signal and the cover signal are inconsistent; B0 is the bandwidth of the main signal, B i is the bandwidth of the cover signal, when the main signal is in the middle, one cover signal in front and one cover signal behind, satisfying: when the main signal is in front, two cover signals behind, satisfying: when the main signal is behind, two cover signals in front, satisfying: at least one cover signal and the main signal have different frequency modulation slopes, the radar linear frequency modulation signal s(t) is wherein, t0 is the delay of the radar signal relative to the synchronization pulse, τ is the pulse width, f0 is the carrier frequency point of the radar signal, and k is the frequency modulation slope of the radar signal. Step 4, transmitting the complex waveforms designed in steps 1-3 in the same synchronization period; Step 5, judging whether the radar main signal is intercepted and interfered, if yes, transforming the arrangement form of the cover signal and the main signal, repeating steps 1-5 until the interference of the interference party is shaken off.

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