I step away softly, just as I creep here quietly I wave gently, sighing goodbye to the western sky.

轻轻的我走了，正如我轻轻的来；我轻轻的招手，作别西天的云彩。

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The transmission of the sky wave is realized by the reflection from ionosphere, especially after reflecting many times, to achieve global communication.

天波的传播是利用电离层的反射来实现的，尤其是多次反射后可以实现全球通信。

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Ionospheric frequency modulation causes spreading of the surface clutter in Doppler domain which greatly limits the detection performance of HF sky-wave radars.

电离层频率调制导致地表面杂波的多谱勒展宽，极大地限制了高频天波雷达的目标探测性能。

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