Study Of GMTI In Mimo Radar

MIMO radar with co-located antennas, which utilizes the techniques of multi-channel and multi-frequency, and provides larger virtual aperture and more system freedoms, has evident advantages in GMTI and parameter estimation. Through the multi-channel and multi-dimensional joint processing of the received echoes, MIMO radar is able to provide more capability in clutter suppression and interference rejection, and solving the GMTI problems in traditional radar, such as slowly moving target detection, the restriction between MDV and velocity range, blind velocity target detection, and so on, which can improve the performance of target detection and parameter estimation.This paper takes GMTI in MIMO radar with co-located antennas as the research object. On the basis of studying and determining the orthogonal signal form suitable to MIMO-GMTI radar, the following issues are studied in the paper: the key problems in MIMO-GMTI of airborne PD system, such as Space-Time-Frequency Adaptive Processing (STFAP), reduced dimension STFAP, multi-frequency fusion detection and parameter estimation based on STFAP, and the key problems in MIMO-GMTI of spaceborne SAR system, such as multi-frequency ATI signal model, performance analysis of multi-frequency combined detection and a deblurring method of velocity measurement. The detailed work of this paper is as follows:Orthogonal signal design for MIMO-GMTI radar is studied in chapter 2. Based on two types of orthogonal signals-orthogonal coding signals with the same frequency band and orthogonal frequency division signals, firstly, the definition of the synthetic ISLR index is proposed according to the transmission diversity characteristic of MIMO radar, which is defined as the ratio of the sum of the integrated energy of all autocorrelation side lobes and all the cross-correlation energy to the integrated energy of the main lobe in the pulse compression function. Secondly, it is theoretically demonstrated that the synthetic ISLR of orthogonal coding signals with the same frequency band is close to 0dB, which can not satisfy the demand of MIMO-GMTI radar system, whereas the cross-correlation energy of orthogonal frequency division signals is nearly 0, which hardly affects the synthetic ISLR. Finally, the results of clutter and imaging simulation using two types of orthogonal signals verify the validity of the theoretical conclusions. Therefore, the orthogonal frequency division signals are selected as the trasmitted signals for MIMO-GMTI radar.The STFAP signal model of MIMO radar is established in chapter 3. Firstly, on the basis of clutter characteristics analysis, the basic principles of suppressing clutter through STAP are described. Secondly, the evaluation criteria for the performance of clutter suppression is studied, including output SCNR, CFAR detection probability, MDV, maximum unambiguous velocity, and so on. Finally, the simulation results of clutter suppression through STFAP demonstrate that MIMO radar is effective in improving the performance of clutter suppression, MDV, blind velocity, velocity range and GMTI.The technique of SCAN-GMTI in MIMO radar based on STFAP is studied in chapter 4. Firstly, on the basis of simulation analysis of clutter characteriscs for each azimuth viewing direction, STFAP technique is adopted to achieve clutter suppression for SCAN-GMTI. Secondly, the unified framework of reduced dimension STFAP is established. The time-space cascade reduced dimension STFAP and the STFAP M-Capon reduced dimension method are proposed. It is presented that the STFAP 3-Capon method based on subarrays has practical meaning for engineering application, which provide some suggestions for implementation of reduced dimension STFAP. Finally, multi-frequency fusion detection and parameter estimation for MIMO radar is studied. The method of multi-frequency fusion detection is proposed based on STFAP. The CRB for moving target parameter estimation is deduced based on STFAP. Simulation results demonstrate that MIMO radar STFAP has evident advantages in improving the performance of target detection and parameter estimation.Based on spaceborne SAR system, the single-baseline signal processing of dual-frequency SAR-ATI with two transmit antennas and two receive antennas is studied in chapter 5. Firstly, according to the working principle and signal model of ATI, the feasibility of combined detection and estimation for dual-frequency SAR-ATI is demonstrated, the statistical distribution of summation of dual-frequency ATI phases for clutter and target is deduced. Secondly, Starting with the distribution of ATI phase, the performance of combined detection and two-step detection with phase and amplitude for dual-frequency SAR-ATI are analyzed, the method of fusion detection is proposed to improve MDV, and the method of detection and fusion is proposed to improve blind velocity, simulation results demonstrate that the combined detection for dual-frequency ATI is effective in improving MDV and blind velocity. Finally, a deblurring method of velocity measurement with dual-frequency is studied. According to different interferometric phase values, three situations are considered to deblur velocity measurement, and the validity of the method is validated through example analysis. Combining the technique of multi-frequency with the technique of multi-baseline, the research findings of this paper can be extended to any MIMO-GMTI system.