However, the system requires 18 satellites to cover Russia; and 24 dependable satellites operating round the clock are needed for accurate global navigation.
该系统需要18颗卫星才能覆盖俄罗斯全境，需要24颗卫星才能实现精确的全球导航。
2
Such as a navigation, notepad, Internet, calendar, clock, calculator, recording, player… A variety of functions witnesses the human progress.
比如导航，记事本，上网，日历，闹钟，计算器，录音，播放器……多种功能见证着人类的进步。
3
Since the Rubidium clock drifts very slowly, an alternative navigation algorithm was designed for Rubidium clock constrained GPS using the adaptive low-pass filter.