half-time emitter

例句：

1. 1.The team's half-time horn signals the end of the first half.
   球队的半场哨声标志着上半场的结束。
2. 2. During the game, the referee uses a half-time whistle to signal the end of play.
   比赛中，裁判使用半场哨来标示比赛结束。
3. 3.The players gather around the half-time emitter to discuss their strategy for the next period.
   球员们聚集在半场发射器旁讨论下一阶段的战术。