A New Method for Resolving Group Targets Moving in Formation with HFSWR
Due to the limited azimuth resolution and spreading Doppler frequency,group targets within the formation are difficult to be resolved for high frequency surface wave radar(HFSWR).In this paper,the inverse synthetic aperture principle is employed for HFSWR,and a cross-range imaging method is proposed.First,the motion compensation processing is performed to eliminate the radial motion and preserve the rotational motion,which enables the realization of a focused Doppler spectrum with resolved mul-tiple sub-targets.Then,the cross-range scaling process converts the Doppler coordinates into cross-range which allows the spacing between sub-targets to be estimated.Specially,the radial velocity and radial acceleration are estimated by the minimum entropy criterion,and the rotational angle is estimated by the fragment digital beamforming.To further enhance the resolution performance under limited integration time,overlapping coherent integration based on the data multiplexing approach is used to increase the number of sweeping periods.The simulation experiments show that the theoretical resolution of the proposed method is in the range of several hectometers to several kilometers;resolved single columns and their spacing estimation can be realized;the overlapping integration has the effect of narrowing the main peaks and reducing the level of side lobes.
high frequency surface wave radargroup targetsinverse synthetic aperturecoherent integration
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