A method for generating dense false target interference based on convolution kernel

Abstract

The present invention provides a method for generating dense false target interference based on a convolution kernel, establishes a unified mathematical model for generating false target interference waveforms, and can generate corresponding dense false target interference waveforms only by controlling an intermittent sampling kernel function sequence and a convolution kernel function sequence. The sampling kernel is used to control the delay distribution of the interference, and the convolution kernel is used to control the interference amplitude and density, thereby increasing the flexibility of waveform generation.

Description

Technical Field

[0001] The invention relates to the field of radar countermeasures, and in particular to a method for generating dense false target interference based on a convolution kernel. Background Art

[0002] In order to achieve the effect of jamming the dense false targets of the radar, modern jammers usually use digital frequency storage technology (DRFM), which can achieve better jamming effect by modulating and forwarding the replica signal of the intercepted radar. At present, the more typical jamming styles include noise convolution jamming, full pulse forwarding jamming and intermittent sampling forwarding jamming.

[0003] Noise convolution jammer convolves the intercepted radar signal with random noise, full pulse forwarding jammer completely copies the intercepted signal and forwards it with a delay, and intermittent sampling forwarding jammer forwards the intercepted signal after sampling it at equal intervals in time. These jammer styles use different methods to generate jammer signals, which can form multiple false targets or dense false targets at the radar end, achieving the effect of suppressing jammers or deceiving jammers. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a method for generating dense false target interference based on a convolution kernel, wherein the sampling kernel is used to control the delay distribution of the interference, and the convolution kernel is used to control the interference amplitude and density, thereby increasing the flexibility of waveform generation.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for generating dense false target interference based on a convolution kernel, comprising the following steps:

[0007] S1. Construct the convolution signal expression of dense false target interference waveform:

[0008] (1);

[0009] in, is the intermittent sampling kernel function sequence; To receive radar signals intercepted by the detection system; is the convolution kernel function sequence;

[0010] The expression after pulse compression is:

[0011] (2);

[0012] in, It is the impulse response of the matched filter in radar signal processing;

[0013] Intermittent sampling kernel function sequence The expression is:

[0014] (3);

[0015] in, is the pulse fast time; is the pulse width of intermittent sampling; is a complete received signal pulse width The number of internal intermittent sampling cycles; The value range is arrive ,when When it is a positive number, it represents a delay cycle, when When it is a negative number, it means advance cycles; is the period of intermittent sampling; is the Dirac function.

[0016] Furthermore, it also includes:

[0017] S2, is the received radar signal, and the expression is:

[0018] (4);

[0019] in, is an imaginary unit; is the frequency modulation slope of the linear frequency modulation signal LFM;

[0020] Matched filter impulse response in radar signal processing for:

[0021] (5);

[0022] Convolution kernel function sequence for:

[0023] (6);

[0024] in, It is the interference amplitude modulation function, which is used to adjust the amplitude of the false target; Is a positive integer; used to control the false target interval; Pulse width The total number of sampling points within ; is the sampling period; is the actual number of sampling points during interval sampling; for A sequence of integers in ranges.

[0025] Furthermore, it also includes:

[0026] S3. Substitute (3) to (6) into formula (2) to obtain:

[0027] (7).

[0028] Furthermore, the intermittent sampling kernel function sequence The Fourier transform of the first window function is:

[0029] (8);

[0030] The intermittent sampling kernel function sequence The Fourier transform of the second impulse train is:

[0031] (9);

[0032] in, is the intermittent sampling frequency.

[0033] The intermittent sampling kernel function sequence The Fourier transform of is:

[0034] (10).

[0035] Furthermore, the Fourier transform of the first two terms of formula (7) is:

[0036] (11);

[0037] in, For radar signal The Fourier transform of formula (11) is:

[0038] (12);

[0039] The formula (7) is transformed into:

[0040] (13);

[0041] in, Delay , the Doppler frequency is The signal passes through a matched filter.

[0042] The beneficial effects of the present invention are as follows: by controlling the intermittent sampling kernel function and the convolution kernel function, the method can flexibly generate dense false target interference patterns such as noise convolution interference, full pulse forwarding interference and intermittent sampling forwarding interference without copying, delaying or frequency shifting the replica signal, and can flexibly adjust the delay, frequency shift, spacing and amplitude of the interference, thereby reducing the difficulty of generating interference waveforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a flowchart of a method for generating dense false target interference based on convolution kernel;

[0044] Figure 2 To suppress the interference effect after noise convolution pulse compression;

[0045] Figure 3 It is the deceptive interference effect after noise convolution pulse compression;

[0046] Figure 4 Suppress the interference effect after pulse compression for full pulse forwarding;

[0047] Figure 5 It is the deception jamming effect after full pulse forwarding pulse compression;

[0048] Figure 6 Direct forwarding of interference pulse compression effects for intermittent sampling;

[0049] Figure 7 Repeated forwarding of interference pulse compression effects for intermittent sampling. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0051] Currently, typical dense false target interference styles include noise convolution interference, full pulse forwarding interference and intermittent sampling forwarding interference. Unlike traditional noise interference, these types of interference utilize radar signal information, so a certain signal-to-noise ratio gain can be obtained at the radar signal processing end, so the interference effect is better.

[0052] Noise convolution interference generation method:

[0053] Noise convolution jammer intercepts radar transmission signals through the detection and reception system, convolves them with random noise, and then forwards them. The mathematical model of noise convolution jammer is:

[0054] J pc 1 = [ s ( t ) ⊗ s ( t ) ] ⊗ h ( t ) = [ s ( t ) ⊗ h ( t ) ] ⊗ s ( t ) (101);

[0055] in, J pc 1 = [ s ( t ) ⊗ s ( t ) ] ⊗ h ( t ) = [ s ( t ) ⊗ h ( t ) ] ⊗ s ( t ) is random noise, is standard normal distribution random noise;

[0056] Radar signals intercepted by the detection system J pc 1 = [ s ( t ) ⊗ s ( t ) ] ⊗ h ( t ) = [ s ( t ) ⊗ h ( t ) ] ⊗ s ( t ) The signal after radar signal processing matched filter is:

[0057] J 1 pc = [ s ( t ) ⊗ s ( t ) ] ⊗ h ( t ) = [ s ( t ) ⊗ h ( t ) ] ⊗ s ( t ) (102);

[0058] The first half of formula (102) represents the noise convolution interference passing through the matched filter, and the second half of formula (102) represents the intercepted radar signal passing through the matched filter and then convolved with the noise. The two are equivalent.

[0059] Full pulse forwarding interference generation method:

[0060] Full pulse forwarding jammer copies the intercepted radar signal into multiple copies for storage, and then forwards it with a delay. The mathematical model is:

[0061] (103);

[0062] in, is the number of false target signals that need to be generated; For false target Delay time relative to the real target;

[0063] The signal after passing through the radar end matched filter is:

[0064] (104);

[0065] Interference signal matched filtering is equivalent to The false target signal to be generated is delayed and then passes through a matched filter;

[0066] Intermittent sampling and forwarding interference generation method:

[0067] Intermittent sampling and forwarding interference is to use sampling pulses to intermittently sample the intercepted radar signal and then forward it. The mathematical model is:

[0068] (105);

[0069] The signal after passing through the radar end matched filter is:

[0070] (106);

[0071] From equations (101) to (106), we know that the generation principle and mathematical model of each interference are different. Different hardware circuits need to be designed according to different interference methods during implementation.

[0072] like Figure 1As shown in the figure, after the receiver receives the radar signal, it amplifies and filters the echo signal and sends it to the down-conversion module. The RF signal is shifted to the baseband signal through the local oscillator signal and sent to the digital frequency storage technology DRFM for storage. Then, it is combined with the intermittent sampling core in the multiplier. Multiply, in the convolution unit, with the pre-generated convolution kernel function Convolution is performed, and the interference signal is mixed with the local oscillator in the up-conversion to shift the frequency from the baseband to the radio frequency, and finally sent to the power amplifier module for power amplification before the interference signal is transmitted.

[0073] A method for generating dense false target interference based on a convolution kernel comprises the following steps:

[0074] S1. Construct the convolution signal expression of dense false target interference waveform:

[0075] (1);

[0076] in, is the intermittent sampling kernel function sequence; To receive radar signals intercepted by the detection system; is the convolution kernel function sequence;

[0077] The expression after pulse compression is:

[0078] (2);

[0079] in, is the impulse response of the radar matched filter;

[0080] Intermittent sampling kernel function sequence The expression is:

[0081] (3);

[0082] in, is the pulse fast time; is the pulse width of intermittent sampling; is a complete received signal pulse width The number of internal intermittent sampling cycles; The value range is arrive ,when When it is a positive number, it represents a delay cycle, when When it is a negative number, it means advance cycles; is the period of intermittent sampling; is the Dirac function.

[0083] Also includes:

[0084] S2, is the received radar signal, and the expression is:

[0085] (4);

[0086] in, is an imaginary unit; is the frequency modulation slope of the linear frequency modulation signal LFM;

[0087] Matched filter impulse response in radar signal processing for:

[0088] (5);

[0089] Convolution kernel function sequence for:

[0090] (6);

[0091] in, It is the interference amplitude modulation function, which is used to adjust the amplitude of the false target; Is a positive integer; used to control the false target interval; Pulse width The total number of sampling points within ; is the sampling period; , , For rounding operation;

[0092] is the actual number of sampling points during interval sampling; for A sequence of integers in ranges.

[0093] Also includes:

[0094] S3. Substitute (3) to (6) into formula (2) to obtain:

[0095] (7).

[0096] The intermittent sampling kernel function sequence The Fourier transform of the first window function is:

[0097] (8);

[0098] The intermittent sampling kernel function sequence The Fourier transform of the second impulse train is:

[0099] (9);

[0100] in, is the intermittent sampling frequency.

[0101] The intermittent sampling kernel function sequence The Fourier transform of is:

[0102] (10).

[0103] The Fourier transform of the first two terms of formula (7) is:

[0104] (11);

[0105] in, For radar signal The Fourier transform of

[0106] The inverse Fourier transform of formula (11) is:

[0107] (12);

[0108] The formula (7) is transformed into:

[0109] (13);

[0110] in, Delay , the Doppler frequency is The signal passes through a matched filter.

[0111] Dense false target jamming waveform kernel model selection and jamming effect simulation:

[0112] Formula (13) is the mathematical model of dense false target interference through matched filtering. Formula (13) is used to generate a typical false target interference signal and simulate the effect of the interference after passing through the matched filter.

[0113] Noise convolution interference:

[0114] According to formula (102) and formula (2), the intermittent sampling function sequence is a full 1 sequence, and its length is the same as the signal sequence; the convolution kernel function sequence is a random noise sequence, and its length is also the same as the signal sequence, that is:

[0115] (201);

[0116] Formula (201) is equivalent to setting formula (13) , , , the expression of noise convolution interference after pulse compression is obtained:

[0117] (202);

[0118] Formula (202) indicates that after the signal is pulse compressed, the number of peaks is , the peak value is The peak time occurs at .

[0119] when When the target signal is output after matched filtering, The output after pulse compression after convolution interference with noise like Figure 2 As shown, it can be seen that the signal of the convolution noise interference after pulse compression is densely distributed around the target, which can form a suppression interference effect. At this time, the amplitude of the dense false target suppression interference is random, and the random value is related to the random value of the convolution noise.

[0120] when When , it means that noise appears at intervals of 96 sampling points. The output result of the target signal after noise convolution interference and matched filtering is as follows Figure 3 As shown in the figure, it can be seen that the signal of the convolution noise interference after pulse compression is sparsely distributed around the target, which can form a deception interference effect. At this time, the amplitude of the deception interference is also random, and the random value is related to the random value of the convolution noise. It can be seen that the interval of dense false targets can be controlled by The value size can be flexibly controlled.

[0121] Full pulse forwarding jammer

[0122] According to formula (104) and formula (2), the intermittent sampling kernel function sequence is a 1 sequence, and its length is the same as the signal sequence; the convolution kernel function sequence is an intermittent impulse train sequence, and its length is also the same as the signal sequence, that is:

[0123] (203);

[0124] Formula (203) is equivalent to setting formula (13) , , ,Right now , ,

[0125] The expression of full pulse forwarding interference after pulse compression is:

[0126] (204);

[0127] Formula (204) indicates that after the signal is pulse compressed, the number of peaks is , and the actual number of sampling points when sampling at intervals according to formula (6) The peak value is The peak time occurs at .

[0128] when When the target signal is output after matched filtering, Output result after matched filtering with full pulse forwarding interference like Figure 4 It can be seen that the signal of full pulse forwarding interference after pulse compression is densely distributed around the target and is basically of equal amplitude, which can also form the effect of suppressing interference. At this time, the amplitude of suppressing interference of dense false targets is basically the same.

[0129] when When , it means that the value appears at intervals of 96 sampling points. The output result of the target signal after noise convolution interference and matched filtering is as follows Figure 5 As shown in the figure, it can be seen that the signal of convolution noise interference after pulse compression is sparsely distributed around the target, which can form a deception interference effect. At this time, the amplitude of the deception interference of dense false targets is basically the same. It can be seen that the interval of dense false targets can be controlled by The value size can be flexibly controlled.

[0130] Intermittent sampling forwarding interference

[0131] According to formula (6) and formula (2), the intermittent sampling kernel function sequence is an intermittent pulse train signal; the convolution kernel function sequence is an intermittent impulse sequence, that is:

[0132] (205);

[0133] The expression of intermittent sampling forwarding interference after pulse compression is:

[0134] (206);

[0135] when At this time , , Contains only frequency shift terms , at this time, it is intermittent sampling and direct forwarding interference, , The pulse compression results are as follows Figure 6 shown.

[0136] when hour, , , at this time it is intermittent sampling repeated forwarding interference, , , repeated twice, the pulse compression results are as follows Figure 7As shown. It can be seen that through the control The value can flexibly control the number of repeated forwarding times.

[0137] Therefore, by flexibly adjusting the intermittent sampling kernel in formula (13) and convolution kernel , can flexibly generate several types of typical dense false target interference signals.

[0138] The above-mentioned embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be based on the attached claims.

Claims

1. A method for generating dense false target interference based on convolution kernel, characterized in that: The following steps are involved: After the receiver receives the radar signal, it amplifies and filters the echo signal and sends it to the down-conversion module. The RF signal is shifted to the baseband signal through the local oscillator signal and sent to the digital frequency storage technology DRFM for storage. Then, it is combined with the intermittent sampling core in the multiplier. Multiply, in the convolution unit, with the pre-generated convolution kernel function Convolution is performed, and the interference signal is mixed with the local oscillator in the up-conversion to shift the frequency from the baseband to the radio frequency, and finally sent to the power amplifier module for power amplification before the interference signal is transmitted. S1. Construct the convolution signal expression of dense false target interference waveform: （1）； in, is the intermittent sampling kernel function sequence; To receive radar signals intercepted by the detection system; is the convolution kernel function sequence; The expression after pulse compression is: （2）； in, is the impulse response of the radar matched filter; Intermittent sampling kernel function sequence The expression is: （3）； in, is the pulse fast time; is the pulse width of intermittent sampling; is a complete received signal pulse width The number of internal intermittent sampling cycles; The value range is arrive ,when When it is a positive number, it represents a delay cycle, when When it is a negative number, it means advance cycles; is the period of intermittent sampling; is the Dirac function.

2. The method for generating dense false target interference based on convolution kernel according to claim 1, characterized in that: Also includes: S2, is the received radar signal, and the expression is: （4）； in, is an imaginary unit; is the frequency modulation slope of the linear frequency modulation signal LFM; Matched filter impulse response in radar signal processing for: （5）； Convolution kernel function sequence for: （6）； in, It is the interference amplitude modulation function, which is used to adjust the amplitude of the false target; Is a positive integer; used to control the false target interval; Pulse width The number of sampling points within is the sampling period; is the actual number of sampling points during interval sampling; for A sequence of integers in ranges.

3. The method for generating dense false target interference based on convolution kernel according to claim 2, characterized in that: Also includes: S3. Substitute (3) to (6) into formula (2) to obtain: （7）。 4. The method for generating dense false target interference based on convolution kernel according to claim 3, characterized in that: The intermittent sampling kernel function sequence The Fourier transform of the first window function is: （8）； The intermittent sampling kernel function sequence The Fourier transform of the second impulse train is: （9）； in, is the intermittent sampling frequency; The intermittent sampling kernel function sequence The Fourier transform of is: （10）。 5. A method for generating dense false target interference based on convolution kernel according to claim 4, characterized in that: The Fourier transform of the first two terms of formula (7) is: （11）； in, For radar signal The Fourier transform of The inverse Fourier transform of formula (11) is: （12）； The formula (7) is transformed into: （13）； in, Delay , the Doppler frequency is The signal passes through a matched filter.

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