| Due to the combination of the advantages of meter-wave radar and multiple input multiple output(MIMO) technology, meter-wave MIMO guidance radar system has potential advantages of anti-jamming, anti-stealth, low probability of intercept(LPI), anti-radiation missile and will have broad application in the future. The signal processing method and correlated theories of meter-wave MIMO guidance radar operating in the semi-active guidance mode are studied in this paper.1. In this paper, the composition of meter-wave MIMO guidance radar system is introduced. And the planar model and spatial model of the system are established. FMICW waveform characteristics and parameter selection are researched and the orthogonality of FMICW is demonstrated.2. Then, the theory of seeker signal processing is introduced, which includes: multi-rate signal processing, stretch signal processing, synthetic impulse and aperture processing, constant false alarm rate(CFAR) detection theory and monopulse estimation. The purpose of multi-rate signal processing is to reduce the sampling frequency of the sub-array and the data rate; the channel separation of orthogonal FMICW and rough measurement of the target distance is completed in stretch signal processing; the precise measurement of the target distance and rough measurement of the target angle are proceeded in synthetic impulse and aperture processing theory; the useful targets in the interference background are detected using CFAR detection; monopulse estimation is used to precisely measure the target angle on the basis of the rough measurement of the target angle. The seeker signal processing flow of the MIMO guidance radar system is as follows: digital intermediate frequency quadrature sampling, channel separation, rough measurement of the target distance, precise measurement of the target distance and rough measurement of the target angle, CFAR detection, and precise measurement of the target angle. The mathematical model of the seeker signal processing flow is established, and the corresponding MATLAB simulation results are given. The simulation results demonstrate that the processing modules can complete the corresponding function.3. For the precise measurement of the target angle, the application and comparison of the sum and differential monopulse algorithm and the digital monopulse algorithm based on window function in the meter-wave MIMO guidance radar system are studied. The effect of operating parameters of the radar and errors of target velocity and ranging on both monopulse algorithms is investigated, and the corresponding MATLAB simulation results are given. The simulation results show that the monopulse algorithms can improve the accuracy of angle measurement for the meter wave MIMO guidance radar.According to MATLAB simulation results, high precision of the target range and angle can be obtained after the designed seeker signal processing. However, there are two problems which are remained to solve:(1) the doppler shift caused by the target radial velocity will result in large errors of the rough target range measurement;(2) the ranging error will lead to a large angle measurement error due to the angle and range phase coupling. |
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