Study On Time-varying Orthogonal Waveformoptimization Design For Anti-jamming

Radar emission waveform design plays a key role due to the requirements of different systems and tasks for modern radar systems.In the environment of rapid development of radar waveform theory,multi-emission has become a breakthrough point,and it has become a trend to design radar multi-transmission orthogonal signals.In order to solve the problems that between multi waveform interference and anti time distance deception jamming distance,etc.It is necessary to ensure the orthogonal relationship between the transmitted signals.The designed for rejecting distance deception jamming of time-varying multiple transmitting orthogonal waveforms is the main content of this thesis.This thesis introduces the characteristics and design methods of radar waveform firstly.The basic radar waveforms include single frequency signal waveform,LFM(Linear Frequency Modulation)signal waveform,NLFM(Nonlinear Frequency Modulation)signal waveform,frequency-coded signal waveform and phase-coded signal waveform.According to the characteristics of multi transmitting orthogonal signal waveform,several common orthogonal signal waveform design theories are introduced.This thesis mainly uses the OFDM(Orthogonal Frequency Division Multiplexing)technology and the traditional radar emitter signal waveform design method to design the radar multiple transmit time variant orthogonal signal waveform,which is mainly orthogonal signals such as OFDM-LFM(Orthogonal Frequency Division Multiplexing-Linear Frequency Modulation),and analyses the orthogonal signal sub signal between the autocorrelation and cross-correlation characteristics of each signal.The generalized radar transmit waveform design not only includes the optimization of the signal shape of the radar transmitter,but also includes the optimization of the receiver filter.Therefore,the optimization of the radar receive filter weight is also a key technology.In the light of this content,introduced the design of matched filter theory and mismatched filter design theory firstly,and then introduces the variable orthogonal signal based on the OFDM model of the matched filter design theory.For the OFDM-LFM orthogonal signal designed in this thesis,a joint optimization waveform design method based on genetic algorithm and sequential two time planning algorithm is presented.Based on the genetic algorithm,the frequency relation of the OFDM-LFM sub signals is broken,and the frequency coding of the OFDM-LFM orthogonal signal is obtained.Then select the phase by the fixed frequency of the sequence two programming algorithm,thus the OFDM-LFM orthogonal signal with low pulse pressure side lobe is obtained.Finally,the feasibility and effectiveness of the joint optimization algorithm of OFDM-LFM orthogonal signals are verified by simulations and results analysis.