计时起点 meaning in Chinese

time reference point
time zero
zero-time reference

In the experimental system apd transferred laser pulse to weak electrical current . after two - level amplification we got a voltage pulse that had a enough amplitude to be applied , the timing point was discriminated by the constant - fraction timing discriminator circuit . timing circuits transferred the pulse flight time to digital signal accurately
实验系统采用apd作为光电传感器，将激光脉冲信号转变为微弱电流脉冲，经过两级放大后，信号变为幅度较大的电压脉冲，经过时点鉴别电路分别确定计时起点和终点后，由计时电路来精确测量两个时间点之间的时间间隔。