基于被动合成孔径的单星无源高精度定位方法

High‑precision emitter localization based on spaceborne passive synthetic aperture

针对传统单星无源定位方法受瞬时测频和测角精度的影响,定位精度多为千米量级,无法实现对舰艇编队、车辆编队等密集编队目标的识别,分辨率低,提出了基于被动合成孔径的单星无源定位方法,将辐射源目标相对于卫星的位置化为方位向和距离向参数。在距离向上,利用距离、卫星等效速度和调频率的关系,通过离散傅里叶变换实现对调频率的准确估计,实现了距离向高分辨;在方位向上,通过脉冲压缩在较长合成孔径时间内,卫星合成了一个长达数千米的虚拟天线孔径,合成后的极窄波束实现了辐射源方位向高分辨。通过公式推导证明其方位向上的分辨率与天线孔径的平方是一个数量级,距离上的分辨率是天线孔径的一半,均可达到米级的分辨率。最终通过无人机实验和卫星数据证明了该方法的可行性。

Traditional passive localization methods are often limited by frequency and angle measurement errors.The positioning accuracy of conventional methods is mostly on the order of kilometers,which cannot identify dense formation targets such as ship formations and vehicle formations.A single-satellite localization method base on passive synthetic aperture is proposed,which converts the position of the emitter target into azimuth and range parameters.In range direction,the relationship between range distance,satellite velocity and Doppler rate is used to estimate range distance.The accurate estimation of Doppler rate is achieved by discrete Fourier transform(DFT);in azimuth direction,through pulse compression the Doppler component can accumulate to synthesize an equivalent large virtual satellite antenna azimuth aperture,and the synthesized extremely narrow beam can achieve high resolution of the azimuth direction of the radiation target.The formulas proved that azimuth resolution is an order of magnitude with the square of antenna aperture,and the range resolution is an order of magnitude with half of the antenna aperture.Both can reach a meter-level resolution.Finally,the feasibility of the proposed method is proved by unmanned aerial vehicle and satellite experiments.