Radar Waveform Design And Anti-jamming Performance Research

The increasingly complex and changeable electromagnetic environment and the continuous development of modern electronic warfare technology have brought severe challenges and threats to radar,especially active deceptive interference.Its transmission waveform has strong coherence with the radar transmission waveform,which leads to the reduction of the radar receiver's discrimination and suppression capabilities,which seriously affects the radar's target detection capability.Since active deceptive interference depends on the radar transmission waveform,this thesis mainly focuses on the design of radar transmission waveform and its anti-interference performance.Based on the basic principles of ESM receivers and DRFM,this thesis proposes basic guidelines and methods for waveform design.That is,the waveform design with low interception characteristics and low coherence between pulses destroys the jammer's reconnaissance and interception,making it difficult to obtain sufficient coherent processing gain for the interference signal copied by the jammer at the receiver,thereby achieving the purpose of countering active deceptive interference.Aiming at the problem of radar transmission waveform design with low correlation between pulses,this thesis focuses on the research of its transmission signal model,fuzzy function,and signal processing method at the receiving end based on step frequency signals and random step frequency signals.Then focuses on two issues:1.Aiming at the problem that the conventional method cannot effectively reduce the sidelobe of the random step frequency signal,a method of suppressing the distance Doppler sidelobe of the random step frequency signal by compressed sensing technology is studied.This method can eliminate the distance Doppler sidelobe to a certain extent.2.Based on the false target interference model of random step frequency signals,this thesis analyzes the anti-interference performance of random step frequency signals and simulates them.The simulation results show that when a random step frequency signal is used,because the interference signal and the real target echo have a certain difference in the slow time domain,the interference echo cannot obtain enough coherent gain to form a false target peak,which can effectively combat active deceptive interference,but the anti-interference performance of the signal will be affected by the number of transmitted pulses.Aiming at the problem of the design of the transmission waveform with low interception characteristics,this thesis studies the transmission signal model,fuzzy function,and signal processing method of the receiving signal of the multi-carrier signal,especially the multi-carrier phase-coded signal.For its excessively high PMEPR,iterative limiting method was used to effectively suppress it.In order to obtain a transmission signal with better anti-interference performance,this thesis combines multi-carrier phase-coded signal with a random step frequency signal,and proposes two different design methods of transmssion waveforms.The random frequency is introduced into the inter-pulse and intra-pulse of the multi-carrier chaotic coded pulse train,respectively.The analysis and simulation experiments of the anti-interference performance of these two signals are finally concluded:compared with the random step frequency signal,the combined two signals not only have more complicated intra-pulse forms and good low-intercept characteristics,but also the inter-pulse correlation is further reduced.