guard band filter

例句：

1. 1. The guard band filters the crowd to ensure safety.
   警戒带过滤人群以确保安全。
2. 2. The police used a guard band filter to prevent crime.
   警方使用警戒带过滤器以防止犯罪。
3. 3. The engineer designed a guard band filter that could effectively remove pollutants.
   工程师设计了一个警戒带过滤器，可以有效地去除污染物。