Research Of Detection Of Slowly Ground Moving Targets With Airborne Radar

GMTI of the airborne radar can capture moving targets at slow speeds, which include the detection of high value time critical targets .Up to now, GMTI has been an urgently needed function of military airborne due to its application in air-toground attacking, and also an important subject in the field of radar study . How to effectively apply to the existing airborne PD radar is discussed in this paper.In introduction section, the basic concept of MTI is introduced. The development history of GMTI of airborne radar is reviewed firstly. Then the difficulties in dectecting targets at slow speeds with the airborne radar is presented. Finally, a compensation way with suni and difference beams of monopulse antenna of fire control PD radar is put forward to reject fixed clutters, so as to effectively recover targets at slow speeds from clutters in the range of mainlobe.In section one, the echo of the airborne radar is analyzed. Several factors affecting the expansion of the spectrum of the clutters are discussed, which includes (l)the effects of relative movement of scattering body in illumination area to the spectrum of clutters;(2) the effects of antenna scan to the spectrum of noise;(3)the effects of platform motion to the spectrum of noise;(4)the effects of the noise of the radar system to the spectrum of noise and so on .The corresponding noise spectrum are given. Then the principle for return signals of airborne radar is simulated with computer, where the simulation of mainlobe clutters is emphasized.In section two , a scheme of moving compensation for monopulse radar is presented based on analyzing the effects of platform motion on MTI performance. The principle for compensating sum channel signals with difference channel signals to reject clutters is analyzed in detail. A formula of compensation factor is derived from the LMS criterion of the lowest residual power of the noise. Afterwards, the scheme is comprehensively evaluated based on computer simulation.In section three, effects of the ground clutters on moving target detection is studied. Firstly , the geometrical relation of the intersection between radar and moving targets is analyzed, then the detailed geometrical relationships of sidelooking and squint looking respectively. After that, the flow chart of emulating the whole radar system is given. From the chart, the compensation scheme for monopulse radar movement is emulated, and the results which demonstrates the feasibility of the scheme are given. Finally , the detection performance is analyzed in detail and the probability of the detection of the targets is gained.The summary section points out that the above scheme can be furtherly studied for different radar MTI filters. Such as, we can evaluate the scheme furtherly with the real echo data, which lays a foundation of engineering implementation.