关键词: 三维成像, 前视阵列雷达, 信源数估计, 波达方向估计, 空间平滑

Abstract: A three-dimensional imaging method for airborne forward-looking array radar is presented in this paper,in which the technique for the estimation of signal source number and direction of arrival(DOA),usually used in array signal processing,is applied.On the basis of two-dimensional imaging,the vector constructed from the images among multiple continuous pulses could be presented as the summation of multiple sine signals from different scatters after the preprocessing of these images,and thus high resolution processing techniques could be used to estimate the number and the frequency of the sine signals,which can be applied to determine the three-dimensional image of the scene.Compared to the traditional imaging method with three-dimensional matched filtering,the method in this paper makes use of the matched filtering of the broadband signal to realize the high resolution over the along-track orientation,as well as the successive pulse signal to realize the high resolution over the altitude orientation.Moreover,the method can reduce the restriction to the flight trajectory because only dozens of pulses are used,and the aircraft can carry out flying more flexible.Compared to the interferometric three-dimensional imaging method,this method could detect and recover every scatter even if multiple scatters are projected to the same pixel,which is usually called for layover.Meanwhile,the method directly use the data in the same pixel for detection to estimate the image correlation matrix,and therefore can realize the there-dimensional imaging effectively even in the situation of seriously inhomogeneous images.

Key words: three-dimensional imaging, forward-looking array radar, estimation of signal source number, estimation of direction of arrival, space smoothing