Location: GNSS AND LORAN

The basis of navigation technology being used in the air, at sea, and on the ground is a global satellite system. The GPS and systems like Loran-C that compensate for the vulnerability of GPS should not be seen as rivals. This is not a war and if it is a war then the GPS is on a very strong wicket. There was a time, not long ago, when even navigation professionals believed in ‘sole-means GPS’. That meant using raw, unaugmented GPS for safety-critical services! But it is already outdated. GPS augmentations such as WAAS, EGNOS and LAAS – both satellite and terrestrial augmentations – have been the focus of satellite navigation development for the past decade.

Now the debate has another focus. It is now realized that all the augmentations in the world will be of no avail if GPS itself is lost. The Volpe Report from the US Government’s own Department of Transportation has outlined the risks we take if GPS is our only means of navigation, or is the only source of the precise timing that ties together nation’s telecommunications system. The Volpe Report says clearly that unintentional or intentional interference to GPS can be reduced, but never eliminated. Losing GPS would cause severe safety and economic damage to the US. GPS is a tempting target for individuals, groups or countries hostile to the US. GPS can be jammed, and its receivers can be spoofed into giving hazardous, misleading information. The Volpe Report tells that we need backup systems and procedures in critical applications, since GPS itself is very vulnerable.

How Vulnerable is GPS?
There’s a jammer hidden in the little dice shown in Figure I. It can kill GPS for a range of 100m or so. A more powerful model could jam GPS across Paris. It would stop GPS in cars, mobile phones and aircrafts. In many countries, it would kill GPS-synchronized mobile-phone sites. It could cause the loss of both communications and power-grid synchronization. Who would deal with that problem? What authority here in Paris is ready and equipped to track down a powerful jammer installed in a car? None at all.

Figure 1. This small dice contains a jammer that can remove GPS throughout a building (Picture: Professor Durk van Willigen).

GNSS AND LORAN – C