Study On Multi-carrier Phased Coded Radar Signal

Low Probability of Intercept(LPI)radar adopt wideband signal as transmitted signal waveform of radar system.Traditional wideband signal are linear frequency modulation(LFM)pulse signal and non-linear frequency modulation(NLFM)pulse signal,which have disadvantages of low complexity waveform,intensive distribution of energy time-frequency that are easy to be intercepted by the hostile forces.Multi-carrier phased coded radar signal,a combination of advantages of phase-coded signal and the Orthogonal Frequency Division Multiplexing(OFDM)scheme,has become an hot topic in recent years in the field of radar research.In this paper,a series of research will be done around the key problems of MCPC signals.We firstly introduced the MCPC signal in this thesis.And the autocorrelation function(ACF)performance of MCPC signal is investigated by using diversity coded.In the investigation,a quantitative analysis is carried out for the LPI and ACF of the MCPC signal with diversity code.The invsetigation results show that the MCPC signal has a lower Peak-to-Side-Lobe Ratio(PSLR)and a better LPI performance compared with typical OFDM signal and other typical LPI signals.Moreover,when chaotic biphase codes mapping with Logistic used to generate the MCPC signal,optimum LPI performance can be achieved.Secondly,as for the Peak-to-Mean Envelope Power Ratio(PMEPR)issue,we proposed a DFT-spread method.Compared with traditional subcarrier amplitude and phase weighted method,and iterative clipping method,DFT is easier to be implemented in real engineer applications.Most importantly,the proposed method can effectively reduce the PMPER of the MCPC signalThirdly,to further reduce the PSLR and to achieve a better anti-jamming performance,based on phase stationary theory of NLFM signal,a Inter-Pulse Non-uniform Random frequency hopping and intra-pulse Multi-Carrier Chaotic Phase Coded(IPNUR-MCCPC)signal was proposed,and a ambiguity function was derived.Meanwhile,an analysis is carried out for the delay performance and Doppler performance of the signal.The results show that compared with Inter-Pulse Stepped frequency hopping and intra-pulse Multi-Carrier Chaotic Phase Coded(IPS-MCCPC)and Inter-Pulse Costas frequency hopping and intra-pulse Multi-Carrier Chaotic Phase Coded(IPC-MCCPC)signals,the IPNUR-MCCPC has a lot of advantages such as lower PSLR and lower periodic side-lobe,no range-Doppler coupling,etc.,due to the unlimited nonlinear property of the used frequency modulation sequence in the IPNUR-MCCPC generation.The result verifies that the IPNUR-MCCPC is an excellent radar signal with good LPI and perfect anti-jamming performance and high range resolution simultaneously.Finally,an instrinsic relationship of the IPNUR-MCPC signal's parameters was analyzed,and a scheme of waveform design and optimization was put forward.At last,the optimized IPNUR-MCCPC signal is not only a low PMEPR waveform,but also a good ACF performance.