Obviously the foundation of electronicnavigationsystem can not meet this need, So human envisaged the possibility of radio transmitting stations on the air.
显然地基电子导航系统不能满足这种需要，于是人类就设想是否可以将无线电发射参考站建立在空中。
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Now, in many parts of the world, when you hire a car, you get a navigationsystem — a little electronic map on a screen with a machine voice.
The smart displays provide navigation and collision avoidance visualization from the radar sources and are used together with the Electronic Chart Display and Information System-Navy (ECDIS-N).