Radio and satellite - based navigation systems have greatly reduced the need for large lighthouses in sighting land.

无线电和卫星导航系统已大为降低了对在可视陆地范围内建大型灯塔的需要.

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GPS - Global Positioning System - A satellite - based navigation unit that can be accurate to 10 m.

全球定位系统一套以卫星做为定位系统的导航装备精确度可达十公尺.

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