navigational aid

基本解释

The utility model relates to a free-floating light beacon of navigational aid on water in the sea, a river, or a harbor.
本实用新型是一种海、河港口用水上助航活节式灯桩。
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Considered a navigational aid to ships entering the harbor, the statue was first administered by the U.S Lighthouse Board before eventually falling under the jurisdiction of the National Park Service.
它被认为是给进港的船只导航的标志，因此在归于国家公园管理处管理之前它都是在美国灯塔局管理的。
A radio navigational aid for determining the distance from a selected DME ground station by measuring the time of transmission to and from it.
飞机上的一种无线电导航设备，通过测量电波往返飞机和预选地面（DME）台之间所需要的时间来确定两者间的距离。

Some countries have laws on the books dating back centuries saying that any navigational aid certified by the government has to be controlled by that government and be based within its territorial borders.
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