Because it is very difficult to realize a frequency pattern as exponent curve rising and inverse exponent curve falling by a common hardware logical combination, so it is achieved by software.

以软件方式实现一般硬件组合逻辑难以达到的指数曲线升频和逆指数曲线降频规律。

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Both sending and receiving stations would, however, need some mechanism to encode and control the frequency-hopping pattern.

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It could change the frequency of the Pacific pattern known as El Nino, a cycle of peculiar weather that affects ocean currents and rainfall across the planet.

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The pattern of damage was similar to the pattern of big-storm frequency uncovered by Dr Elsner.

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