subcarrier countdown

例句：

1. 1.The subcarrier countdown is starting, and we need to be ready forthe next phase.
   副载波倒计时开始了，我们需要准备好进入下一个阶段。
2. 2. During the countdown, the audience was eagerly anticipating the launch of the satellite.
   倒计时期间，观众急切地期待着卫星的发射。
3. 3. The countdown ended with a loudbang, signaling the successful launch of thespacecraft.
   倒计时以一声巨响结束，标志着航天器的顺利发射。