Backgrounder: 4 major global navigation systems

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Source: CCTV.com | 04-15-2009 13:41

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The Global Navigation Satellite System, or GNSS, is the standard term for satellite navigation systems. These allow small electronic receivers to pinpoint their location to just a few meters. Receivers on the ground in fixed positions can also be used to calculate precise times as a reference for scientific experiments.

There are currently four major Global Navigation  Satellite Systems in the world, including China's  Compass system.

There are currently four major Global Navigation Satellite Systems in the world, including China's Compass system.