Browsing by Author "Sun, Yongyan"
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Item Air Moving Target Indication in Nadir Region for Spaceborne Surveillance Radar Systems(IEEE Geoscience and Remote Sensing Letters, 2023-06-02) Zou, Zihao; Huang, Penghui; Lin, Xin; Xia, Xiang-Gen; Xi, Peili; Sun, Yongyan; Liu, XingzhaoFor air moving target indication (AMTI) in nadir region, due to the fact that a spaceborne radar beam can illuminate the top of fuselage, the target radar cross Section is usually high, which is beneficial for the detection of a low-observable target. However, due to the short slant range, specular reflection effect, and relatively low radar ground resolution, the power of clutter component from nadir region is comparatively high, leading to the insufficient clutter suppression and the degradation of target detection performance. Fortunately, when an air moving target is adequately high, the target echo can be separated from the main clutter echoes due to a shorter time delay, making it possible to be only mixed with low-power ambiguous clutter echoes. Based on these considerations, this letter analyzes the performance of AMTI in nadir region for a spaceborne surveillance radar system. It analyzes the target minimum detectable velocities with different target heights and beam center elevation angles. Also, an effective sample selection method based on adaptive range segmentation is proposed to solve the power heterogeneity issue between the main clutter area and the range ambiguous clutter area. As a conclusion, the larger the elevation angle of an air moving target is, the higher the minimum target detectable height is.Item Multi-channel Signal Modeling and AMTI Performance Analysis for Distributed Space-based Radar Systems(IEEE Transactions on Geoscience and Remote Sensing, 2022-08-29) Chen, Jiangyuan; Huang, Penghui; Xia, Xiang-Gen; Chen, Junli; Sun, Yongyan; Liu, Xingzhao; Liao, GuishengDue to the limited size, carrying capacity, power-aperture product, and high hardware cost of satellite platform, the traditional single-platform spaceborne radar system encounters the problems of poor target minimum detectable velocity (MDV) performance, considerably deteriorating the moving target detection performance. To improve the air moving target indication (AMTI) performance, especially for a weak target, distributed space-based radar system (DSBR) becomes a good candidate due to the longer along-track baseline (ATB) and spatial power synthesis. However, due to the sparse configuration of radar baseline distribution, the detection performance of air moving targets (AMTs) will be restricted by many practical factors in an actual DSBR system. In this paper, multi-channel signal models of an observed moving target and ground clutter are accurately established in a DSBR framework, where the error influences of cross-track baseline (CTB), terrain fluctuation, and channel inconsistency response are considered. Then, the influence of the non-ideal factors, including the channel noise, long-intersatellite ATB, long-intersatellite CTB, synchronization errors, and interchannel amplitude and phase inconsistency errors, on the AMTI performance is analyzed term by term. The simulation results provide the useful guidance for the system design of a DSBR with the AMTI tasks.