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1·The black box pinger has a range of only a few miles.

黑匣子脉冲发射器的发射范围只有几英里。

2·Underwater GPS positioning system includes four parts which are GPS differential reference station, GPS buoy subsystem, underwater pinger, ship-based data processing and control center.

差分gps水下立体定位系统包括GPS差分基准站、GPS浮标、水下收发机、船基控制中心四部分。