The first one is a sensor head converting the current flowing in the power line into the optical pulse FM signal. The second one is optical fiber transmission and optolectric conversion.

第二部分是光纤传输和光电转换器，从传感头输出的频率调制信号驱动装在高压端的发光二极管，进而转换成光脉冲信号；

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Elements in the military establishment have also felt a need to use the street protest power of these groups as a second line of defence at times of international crises.

BBC: Formidable power of Pakistan's anti-Shia militants