Because CCDs are essentially capacitive devices, they need external control signals and large clock swings to achieve acceptable charge transfer efficiencies.

因为ccd器件本质，他们需要电容外部控制信号，达到大钟波动可接受的电荷转移效率。

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Frequency of external signals is constantly needed to be measured when complex measurement and control instructions are executed in an embedded system.

嵌入式控制系统在执行复杂测量与控制任务的同时，常需要测量外部信号的频率。

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