| In recent years,multiple-input multiple-output(MIMO)radars have received widespread attention from academic researchers in the radar field.The MIMO radar is an emerging system that uses multiple antennas to transmit different waveforms simultaneously at the transmitting end and uses multiple antennas to receive echo signals simultaneously at the receiving end.Compared with phased array radars,MIMO radars have even greater potential in terms of ascending angle,range resolution and suppressing interference.An in-depth study of these directions can significantly improve radar performance such as target detection,parameter estimation,and target tracking.In this paper,some key technologies of MIMO radar in signal processing are analyzed and studied.The main contents include the following aspects:In the first part,the basic principle of MIMO radar and its advantages in radar system are studied.The orthogonal frequency division chirp signal(ie,OFDM-LFM signal)in the orthogonal waveform of MIMO radar is also studied.The autocorrelation and cross-correlation of OFDM-LFM signals are analyzed.The results show that OFDM-LFM signals have good orthogonality.In the second part,the MIMO radar transceiver model is established and the signal processing method is studied.In order to improve the system resource utilization and simplify the system construction,an improved OFDM-LFM matched filter architecture is proposed for the traditional matched filter architecture.Comparing the results before and after improvement,the correctness of the new method is proved.For OFDM-LFM signals transmitted by MIMO radar,the distance resolution can be improved by processing at the receiving end,and the MIMO radar has higher distance resolution than the phased array radar.In the third part,the relative content of MIMO radar goniometry technology is studied,including sum and difference amplitude comparison mono-pulse angle measurement and direct phase comparison mono-pulse angle measurement:(1)The two-way directional pattern of MIMO radar is analyzed,which can form a joint pattern at the receiving end.The width of 3dB main lobe is narrower and the angular resolution is higher.(2)Introduce the theory of sum and difference amplitude comparison mono-pulse angle measurement technology,deduce and simulate the measurement accuracy of MIMO radar and phased array radar.The effects of left and right beam spacing,beam amplitude error and number of array elements on the accuracy of angle measurement are studied.(3)Finally,the principle of direct-phase single-pulse angle measurement is introduced.The virtual array formed by MIMO radar can be equivalent to a triangular array with 2M-1 array elements.Compared with phased-array radar,divided sub-arrays have different received signals.The phase difference between them is not the same,resulting in the measurement accuracy of the two is not the same.The simulation results also show that the use of MIMO radar virtual array technology provides higher angle accuracy. |
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