Reference data for RCS scales, radio-frequency bands, engagement geometries, and representative threat systems are summarised in Annex a.

参考资料来源于rcs减缩、无线电波段、接触几何和典型威胁系统见附录a。

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With the drastic frequency competition of communication, the usual communications with fixed frequency suffer from a serious threat.

随着通信领域的频率竞争愈演愈烈，惯用的定频通信受到了严重威胁。

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Fires are an ever-lurking threat in Australia, but recently they have been breaking out with disturbing frequency.

ECONOMIST: Arson suspected

The insider threat has traditionally been viewed as a high-consequence but low-frequency risk, and many IT organizations have found it challenging to develop effective programs that manage that risk.

FORBES: 5 Key Computer Network Security Challenges For 2013

Interestingly, the movement includes many who still believe that the lower frequency radiation from power lines and electric appliances and motors also poses a cancer threat, in spite of the fact that 30 years of research has shown no effects.

FORBES: Do Cell Phones Cause Brain Cancer? The Diehards Cling Desperately To Opinion