• What is a GPS unit and why do you need one?
• Big brother is watching
• Fun and GPS games
• What to look for in a GPS
• How the GPS works
• More than one system
• Location, location

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 currently in initial deployment phase and is scheduled for full functionality in 2013, while India's IRNSS is aiming to be operational by 2012.

GNSS precision varies, depending on the technology used. For instance, the US Department of Defense originally intentionally degraded GPS signals (Selective Availability, or SA) to prevent others from using the 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, "Selectivl be used to effectively jam civilian GPS units in a war zone, for example, 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 of GPS, is expected to increase this accuracy to within just 1m when it comes online in 2013.

Location, location

GPS has resulted in another breed of services called LBS (location-based services). These services use knowledge about where a GPS-enabled 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. An example of an LBS is Google's Latitude service.

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 (e.g. smartphones); messages are linked to the location of the sender and accessed by any properly equipped mobile user in that local region. Possible uses for this technology include traffic hazard warnings and other emergency services.

Navman's S300T offers a widescreen display and provides access to the SUNA Traffic Channel

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. The SUNA Traffic Channel was launched in 2008 and is currently operational in Sydney, Melbourne and Brisbane. It will be expanding across the country in 2009 and beyond.