beat frequency detector

例句：

1. 1. Thisdevice is used to detect the frequency of human heartbeats.
   这个装置用于检测人类心跳的频率。
2. 2. The beat frequency detector was used to monitor the heart rate of athletes during competition.
   节拍频率检测器被用来在比赛中监测运动员的心率。
3. 3.The beat frequency detector can help doctors diagnose heart conditions more accurately.
   节拍频率检测器可以帮助医生更准确地诊断心脏疾病。