GPS Advisor

More than one system

What most people refer to today as GPS is more accurately called the GNSS (Global Navigation Satellite System), of which the GPS is part run by the USA. Two GNSS systems are currently in operation: the United States' Global Positioning System (GPS) and the Russian Federation's Global Orbiting Navigation Satellite System (GLONASS) – a smaller, and presumably, less effective system with only about a dozen satellites. A third, Europe's Galileo, is scheduled for full functionality in 2008.

GNSS precision varies, depending on the technology used. For instance, the US Department of Defense originally used an intentional degradation (Selective Availability, or SA) of GPS signals to prevent others from using the locating data. Although military accuracy was to within 10 metres, GPS accuracy was limited for civilians (via SA) to a 100m range. SA was discontinued in May 2000. However, for military purposes, "Selective Deniability" (SD) may still be used to effectively jam civilian GPS units in a war zone or global alert while still allowing full functionality for military units. Without SA, GPS receiver accuracy is generally down to 5-10m. Galileo, which is largely the result of European concern over the level of US control over the GPS, is expected to increase this accuracy to within just 1m when it comes online in 2008.

Location, location

The GPS has also resulted in another breed of services called LBS (location-based services). These services use knowledge about where an information device is located to deliver targeted information. For example, the user of a mobile phone could be shown information specific to the region in which it is used. Of course, the downside of this (for a user) is that this information could take the form of advertising – though privacy regulations may curtail the amount and type of unsolicited information that can be sent.

Another upcoming technology that uses GPS is GPS Messaging – a wireless messaging system for location-specific (rather than recipient-specific) messages. The messages are sent and received by people with GPS locators in their wireless devices (eg, smart phones); messages are linked to the location of the sender and accessed by any equipped mobile user in that local region. Possible uses for this technology include traffic hazard warnings and other emergency services.

In Australia, Traffic Message Channel (TMC) is the technology used to deliver traffic and travel information to drivers. This information can be integrated directly into a GPS navigation unit, allowing the user to plan alternate routes. TMC is being launched throughout Australia in 2008.