短相干积累条件下天波超视距雷达的舰船检测
The Ship Detection of Sky Wave over-the-Horizon Radar with Short Coherent Integration Time
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摘要: 天波超视距雷达(OTHR)的观测范围非常广，实战中经常要求在短相干积累条件下检测出舰船目标。然而短相干积累时间带来的低多普勒分辨率很难从强大的海杂波中区分出舰船。为了解决这一问题。可以采用海杂波循环对消法，这就要求对杂波参数进行精确估计。传统方法直接利用Fourier谱中的最大幅度估计杂波参数，估计精度不高从而导致对消性能不太理想。该文提出了一种新的基于FFT相位分析的杂波对消法。该方法与传统的杂波对消相比，有效提高了参数估计精度，减小了剩余杂波强度和扩散程度，有利于舰船目标的峰值显露和从剩余杂波中区分出舰船。以上分析和比较得到了实测数据的检验。Abstract: Since the surveillance area of sky wave Over-The-Horizon Radar (OTHR) is very vast, realizing the ship detection with short coherent integration time (GIT) is an operational requirement for OTHR. However, short CIT and the resulting low Doppler resolution cannot separate the ship target from the close powerful ocean clutter. To resolve this problem, clutter cancellation algorithm can be adopted but it requires accurate estimation for clutter parameters, The conventional cancellation method only uses the maximal amplitude of Fourier transform to estimate the clutter parameters, which may not get satisfied estimation and cause imperfect clutter cancellation. In this paper, the phase information of Fourier transform is combined to provide more accurate estimation of clutter parameters. As the result, the power and spreading of clutter residue are reduced which is helpful for the ship visibility and identification. The above analysis and comparison have been demonstrated by real data.
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