标题： 相对论定位系统：当前状态 显示英文标题

标题： Relativistic Positioning Systems: current status

摘要： 一个{\em 相对论定位系统}包含一组四个钟，它们通过光信号广播各自固有时。 其中，更重要的是{\em 自动定位系统，}，其中每个钟不仅广播自己的固有时，还广播从其他三个钟接收到的固有时。 在这个层次上，不需要参考任何外部系统（例如地球表面）以及不需要同步。 对相对论定位系统的理论现状进行了概述。 显示英文摘要

摘要： A {\em relativistic positioning system} consists in a set of four clocks broadcasting their respective proper time by means of light signals. Among them, the more important ones are the {\em auto-located positioning systems,} in which every clock broadcasts not only its proper time but also the proper times that it receives from the other three. At this level, no reference to any exterior system (the Earth surface, for example) and no synchronization are needed. The current status of the theory of relativistic positioning systems is sketched.