Study On Several Kinds Of Radar Active Deception Jamming And Its Countermeasures

With the rapid development of microelectronics and radio technology,electronic warfare information technology has been continuously upgraded,and the electromagnetic environment faced by radars has become more and more complex.In electronic warfare environment,both parties can use various electronic countermeasures(ECM)to interfere with the enemy's radar system from multiple angles and dimensions.At the same time,they can adopted a variety of electronic counter-countermeasures(ECCM)to electronically defend their radar systems.As a commonly used interference type,the radar active deception jamming can accurately simulate radar echoes to confuse the enemy radar,and affect its detection and tracking of real targets.With the widespread application of digital radio frequency memory technology,the fidelity of false targets simulated by jammers is getting higher and higher,and various new jamming patterns that make the jamming effect more ideal are constantly being developed.The increasingly severe electronic warfare situation poses new challenges to the interference and anti-jamming capabilities of both sides in the modern battlefield environment.In order to effectively improve the radar's ability to resist active deception jamming,this thesis analyzes the working principle and jamming characteristics of traditional active deception jamming and new type active deception jamming respectively,and conducts indepth research on its identification and suppression.In order to improve the effect of radar interference,this thesis also studies the improvement of the new type of active interference generation method.The main research results are summarized as follows:1.Aiming at the identification problem of Velocity Gate Pull-Off(VGPO)jamming,an interference identification method based on Discrete chirp-Fourier Transform(DCFT)is proposed.First,the scale transformation characteristic of the frequency-frequency modulation slope estimation of the DCFT algorithm is analyzed,and the DCFT algorithm model is improved in a targeted manner.Then the estimated results of the frequency and the frequency modulation slope of the pulse repetition period in each pulse repetition period during the process of implementing the gate drag interference in the jammer is deeply analyzed.Finally,by using the quantization characteristics of the frequency modulation slope estimation value when the frequency estimation value is unchanged,and the characteristic of the mean square error ratio of the normalized estimated modulation frequency is designed.the quantization characteristics is that,the change of the frequency modulation slope value estimated by the DCFT algorithm with the pulse sequence and the pseudo-Doppler frequency shift applied by the jammer over time are the same.According to the difference between the target signal and the characteristic value of the VGPO interference signal,the interference signal can be identified.The simulation results verify the effectiveness of the method.2.The countermeasure method against Smeared Spectrum(SMSP)jamming is studied.First,the signal model of SMSP jamming is introduced.Then,the short-time Fourier Transform(STFT)of SMSP interference are theoretically deduced.In order to effectively interference to the radar,in the mixed signal received by the radar including target and SMSP interference,the power of the interference signal is usually greater than the power of the target signal.In this case,by analyzing the STFT results of the mixed signal,a parameter estimation method of SMSP interference is proposed,including the number of sub-waveforms,amplitude,and time delay.Finally,the estimated signal parameters are used to reconstruct the interference signal and remove it from the received mixed signal to complete the interference suppression.The simulation results verify the effectiveness of the method and show that the method can accurately estimate the amplitude of the interference signal.3.Aiming at the problem of the strong regularity of the energy distribution of Interrupted Sampling Repeater Jamming(ISRJ),a new interference generation method of Interrupted Non-uniform Sampling Repeater Jamming(INUSRJ)is proposed.This method destroys the regularity of signal energy distribution by using intermittent non-uniform sampling and nonquantitative retransmission,so that the pulse pressure results of all retransmitted intermittent sampling signals have different peak positions,and the pulse compressed results form an interference effect similar to suppressive jamming.This method firstly analyzes the pulse compressed results of the intermittent sampling signal to construct the generation criterion of the INUSRJ signal,and then uses the tabu search algorithm to solve and optimize the INUSRJ intermittent sampling forwarding times and the sampling pulse width and other parameters.The solution is restricted and adjusted to improve the interference performance.The simulation results verify the effectiveness of the interference generation method.4.The countermeasure methods for new type of repeating interference based on waveform design is studied.Firstly,the method of anti-ISRJ of LFM-Costas frequency step signal in pulse is improved,and a combination of LFM-Costas frequency step signal in pulse is designed to improve the performance of suppressing ISRJ interference.This method adopts the idea of shielding pulse.The shielding pulse signal and the working pulse signal adopt the same modulation method,but the two have a certain frequency difference to ensure orthogonality.The shielding pulse signal and the working pulse are alternately transmitted in turn.When receiving,each working pulse sub-waveform is used for multi-channel reception,and finally the channel where the strong interference is located is eliminated through channel sorting to achieve interference suppression.In addition,a new repeating interference countermeasure method based on combined LFM-M sequence modulation signals is proposed.According to the difference in signal structure between the new-type repeating interference and the target echo,the phase modulation characteristics of the M sequence are used to protect the information contained in the LFM signal transmitted by the radar,and the combined modulation signal is used for transmission and matched filtering to reduce the new-type repeating interference Impact on real goals.Simulation experiments have verified the effectiveness of the anti-interference method of waveform design.