Ground Low-Speed Moving Target Detection for Airborne Phased Array Radar
|School||University of Electronic Science and Technology|
|Course||Signal and Information Processing|
|Keywords||airborne phased array radar ground moving target indication (GMTI) displaced phase center antenna (DPCA) space-time adaptive processing (STAP) chirp-pulse stepped frequency radar|
Clutter cancellation and ground moving target detection is one of key technologies for airborne radar, and phased array technology has been employed widely in airborne radar, so it’s useful to find technologies of ground moving target detection adapted to existing airborne phased array radars and developing a real-time processor with good GMTI (Ground Moving Target Indication) performance.This dissertation is based on airborne side-looking radar and airborne fire controlling (forward-looking) radar, and the main creative work are as follows:At first, a DPCA (Displaced Phase Center Antenna) technology based on digital all-pass interpolation of array elements for SLAR (Side-Looking Airborne Radar) is proposed. This technology inherits advantages of conventional DPCA: its processing is relatively simple and it’s easy to be realized. It’s shown that this technology not only needs lower computation compared with optimum STAP (Space-Time Adaptive Processing), but also its SCR (Signal-Clutter Ratio) IF (improve factor) is higher than that of optimum DPCA with two channels by more than 10dB. So it’s a good choice for airborne side-looking phased array radar.Secondly, in order to adapt to widely used monopulse radar and overcome the real-time realization difficulties of existing EA-STAP, a reduced-rank EA-STAP technology based on DPCA phase compensation is proposed. This technology reduces the rank based on the similar principle of conventional electronic DPCA, and then performs reduced-rank EA-STAP. Its computation is only 1/3 of EA-STAP and its SCR IF loss is only 3dB compared with∑A-STAP, so it’s successfully used in the under-developed radar.Thirdly, A GMTI approach in main-lobe clutter spectrum region is proposed for monopulse airborne fire-control phased array radar. This approach followed a novel idea: the main-lobe clutter spectrum is regular for the deviation azimuth of clutter is corresponding to its Doppler frequency, while the returns of moving targets violate this regularity, so it’s reasonable to use the azimuth error in each Doppler channel as a detector of ground moving target. This approach can achieve very low speed moving target detection, and its GMTI performance gets better with higher platform speed in condition to no spectrum overlapping exists.Fourthly, a decorrelation processing method is proposed to mitigate the along-range spillover problem in GMTI processing in chirp-pulse stepped-frequency radar. This method doesn’t need upsampling processing, so its computation is greatly reduced compared with other existing methods, and this method can effectively solve the along-range spillover problem to improve the SCR of single range unit and reduce the false alarm rate. Moreover, a GMTI processor scheme based on high range resolution processing in chirp-pulse stepped-frequency radar is proposed.Finally, based on above-mentioned research of GMTI technologies, a ground clutter cancellation and GMTI system is designed, this system includes GMTI processing, CFAR (Constant False Alarm Rate) processing and monopulse azimuth measurement. Its all specifications meet contract requirement and has passed through test.