当选择自动增益方式时，增益的改变通过增益同步脉冲触发，触发脉冲可由系统内部周期产生或外部提供。

When the former was chosen, the change of gain would come true by the synchro pulse, which was supplied by the cycle inside the system or outside the system.

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选择外部触发时的录影方式。

Select the recording mode when trigger.

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至于选择何种触发方式，还要 依占空 比是固定的还是随意的来定。

The device may be triggered either automatically or manually and depending on how the device is triggered will also depend on whether the duty cycle is fixed or random.

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