天波超视距雷达瞬态干扰抑制

天波超视距雷达(OTHR)电波通过电离层折射作下视探测,具有观察距离远,观察范围广的特点.但由于采用HF频段,且电波传播环境复杂,不仅海(地)杂波强,而且有很强的干扰,如电台干扰、工业干扰、冲击噪声、闪电冲击和流星余迹回波等.干扰分长时间干扰和瞬态干扰,瞬态干扰持续时间短、强度大.本文首先讨论OTHR接收到的瞬态干扰的特点;然后讨论了瞬态干扰的滤除方法,即采用特征分解方法滤除海杂波,或在频域直接滤除地杂波,检测出瞬态干扰的位置后,在原始信号中挖除存在瞬态干扰的回波点,并用预测内插的方法,消除瞬态干扰谱对目标掩盖作用,使目标特别是舰船目标能被检测出来;最后通过实测数据的检验.

Transient Interference Excision in OTHR

High-frequency(HF) skywave over-the-horizon radar(OTHR) looks down its targets from the ionosphere,it has a large operating range and a large cover areas,but it also receives strong backscatterer echoes from the terrain and sea,and interference,such as radio frequency interference,industrial interference,impulsive noise,lightning impulsive,meteor trail echoes and so on.Interference can be divided into long time interference and transient interference.Transient interference lasts a short time,but its intensity is great.This paper first discusses the character of transient interference,then discusses its excision method,finally the method has been successfully applied to the real data from China experimental OTHR.The transient interference excision method is:first eigen-decomposition is used to separate the sea clutter subspace and filter it or ground clutter is filtered in frequency domain directly,then the transient interference can be detected,after that the original echoes with existing transient interference are excised,finally the excised clutter and target echoes are predicted by Burg linear prediction algorithm.