No GPS? No Problem

By David Hambling
London

Navigation via Global Positioning System is ubiquitous. Soldiers, vehicles and even artillery rounds are guided by satellite navigation, as long as the service is accessible.

But what happens when it isn’t? GPS jamming has always been a concern and much effort has been expended in making the system jam-proof. GPS, however, may be unavailable for other reasons: Obstructions can block ...

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