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超视距雷达能够探测远洋区域的船舶,由于电离层引起的多卜勒频移的变化,干扰了海面回波,所以探测性能有时会降低。本文提出了一种去干扰方法,它建立在海杂波伯拉格谱的极大熵谱分析基础之上,在完成经典的快速傅里叶变换之前修正信号相位,相位修正之后信号质量的改善会导致信号谱峰变尖锐。在介绍的例子中,设立在船上的应答器谱线包含被选择的信号,用作参考谱。对于伯拉格谱和应答器谱,谱宽减少是重要的。当伯拉格谱峰变尖锐时,船舶回波谱较易探测。虽然这种去干扰方法比在海情监测中采用的较简单的频移方法需用较多的计算量,但是另一方面在相干积分时间内这种方法能处理多卜勒频移变化。
OTHR can detect ships in the oceanic region, and the detection performance sometimes decreases due to changes in the Doppler shift caused by ionospheric interference with sea surface echoes. In this paper, a method of interference removal is proposed, which is based on the maximum entropy spectrum analysis of sea clutter. The signal phase is corrected before the classical Fast Fourier Transform, and the signal quality is improved after phase correction Will lead to sharper signal peaks. In the example presented, the transponder line set up on board contains the signal that is selected as a reference spectrum. Spectral width reduction is important for Bragg and transponder spectra. The ship echo spectrum is easier to detect when the Bragg peak is sharp. Although this method of interference removal requires more computation than the simpler frequency-shift method used in sea-state monitoring, this method can handle Doppler shift changes during the coherent integration time.