Study On The Application Of Chaotic Sequence To MIMO Radar Waveform Design

Multiple Input Multiple Output (MIMO) radar is a new radar technique developed recently.In order to improve detecting performance, this radar system capitalizes on the MIMO technology against target RCS scintillations, combining the spatial diversity and waveform diversity. Designing orthogonal waveforms is the precondition and key to ensure the radar's measure precision and resolving power. This thesis puts the emphasis on the study of MIMO radar waveform design, and the main contributions of this thesis are as follows.In consideration of the special configuration and signal processing mode of MIMO radar, the orthogonality and ambiguity rules of waveform design are discussed systematically, and the MIMO radar ambiguity function is derived.A new method applying chaotic sequences to design frequency-hopping coded waveforms and binary-phase coded waveforms of MIMO radar waveform is proposed. By make use of the random likeness characteristic of chaos, problems consisted in general pseudo-random sequence such as the sequence length is limited, the side lobe of autocorrelation is too high and so on can be solved. Besides, the process of waveform design is simplified, and the flexibility of MIMO radar system improved greatly.A kind of multiple waveforms combining binary-phase coding with frequency-hopping coding is designed. By making both the phase and the carrier frequency hop randomly and frequently in certain range, the pulse compression rate, the orthogonality, and the confidentiality of the transmitted signals can be improved.Based on above methods of MIMO radar waveform design, two kinds of amelioration methods which can improve the anti-interference and counterreconnaissance capacity are proposed. By setting different initial values, each pulse of each waveform can be made orthogonal. Without transmitting the same signal periodically, the anti-interference capacity is enhanced, and the problem of range ambiguity is solved. To improve the cloaking ability and reduce the probability of being intercepted, we can make several chaotic sequences mixed or carry on the suitable change to a chaos sequence by crossing, intercepting or sampling.