In many portable instruments, the noise and EMI of its switch power supply must be solved, the preferable method is that EMI power is reduced with spread spectrum frequency technique.

在许多便携式设备中，其开关电源的噪声和电磁干扰(emi)是亟待解决的问题，比较好的办法是利用扩频技术来减少EMI信号的功率成分。

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Spread spectrum, frequency-hopped, which generates many codes over a wide frequency band.

它在很宽的频带上产生许多代码。

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According to different ways of spread spectrum, spread spectrum communication systems are divided into: direct sequence spread spectrum, frequency-hopping spread spectrum and hybrid spread spectrum.

根据扩展频谱方式的不同，扩频通信系统分为：直接序列扩频、跳频扩频和混合扩频。

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But there is a limited amount of radio frequency spectrum available.

VOA: special.2010.03.19

So, let's say they were expecting to see one certain frequency or one line in the spectrum at this point here.

比如说他们预计会看到某个特定的频率,或者在这里看到一个谱线。

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The mobile firm has made no secret of its desire to get its hands on lower-frequency spectrum, which can cover much larger areas and offers better indoor coverage than the high-frequency spectrum it currently owns.

BBC: Mobile firm on rural net crusade

"Low-frequency spectrum on a network as big as ours is a real notspot-killer, " he said.

BBC: Mobile firm on rural net crusade

Developed for secure government communications, Spitfire uses a broad frequency spectrum virtually immune to eavesdropping or interference.

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