Civilian Applications of GPS
The free global availability and accuracy of GPS signals for positioning and timing, combined with the low cost of receiver chipsets, has made GPS the preferred solution for a very wide and growing range of civilian applications.
1. Road Transport
Based on the number of GPS receivers sold globally, road transport applications are the majority users of GPS positioning – for commercial fleet management and freight tracking, taxi services, public transport monitoring and passenger information, and emergency vehicle location, dispatch and navigation. Private car owners have also widely adopted in‑car GPS navigation systems and most automobile manufacturers now release new vehicles with optional factory-fitted GPS.
In commercial aviation, most aircraft now use GPS for en‑route navigation and GPS is increasingly being used for initial approach and non‑precision approach to specified airfields. Automatic Dependent Surveillance ‑ Broadcast (ADS‑B) is being developed globally as the preferred future technology for commercial air traffic control; this involves aircraft calculating their position using GPS and broadcasting it to other aircraft. GPS is also widely used for navigation of unmanned aerial vehicles (UAVs) for professional applications such as resource mapping and aerial surveying – imaging tasks previously performed by satellites such as NASA’s Landsat.
3. Shipping & Rail Transport
Maritime applications include ocean and inshore navigation, dredging, port approaches, harbour entrance and docking, Vessel Traffic Services (VTS), Automatic Identification System (AIS), hydrography, and cargo handling. Railway applications include the management of rolling stock, passenger information, preventing doors opening until the carriage is alongside the platform, cargo tracking signalling, train integrity and level crossing approach.
Scientific applications of GPS are widespread and include environmental and atmospheric monitoring, animal behavior studies, botanical specimen location, meteorology and climate research. GPS is used in agriculture and fisheries for land area mapping, yield monitoring, precision planting of crops, spraying and harvesting, autonomous vehicle control and to monitor fishing limits.
Security applications include tracking of vehicles, containers, other valuable cargoes and covert tracking of suspects.
6. Heavy Vehicle Guidance
GPS is being used increasingly to guide and track heavy vehicles in engineering applications such as mining and construction. For example, in highway construction, surveyors and marker pegs have been replaced with in-cabin vehicle guidance and control systems for excavators, graders, bulldozers and road paving machines that allow drivers to follow a surveyor’s pre-programmed site plans and achieve close tolerances for position, level and gradient.
In open-cut mines, GPS is integrated into applications developed by companies such as Leica Geosystems, Topcon Positioning Systems and Trimble/Caterpillar for vehicle guidance and tracking, and mine asset management systems.
In these professional applications, GPS information is captured by sophisticated IT systems and meshed with other engineering applications to provide multifunction guidance and control.
7. Surveying, Mapping and Geophysics
Professional, survey-grade GPS receivers, capable of utilising signals from both L1 and L2 GPS frequencies, can be used to position survey markers, buildings, bridges and other large infrastructure. GPS is widely used in mapping, including aerial mapping, and other Geographical Information System (GIS) applications. In geophysics, GPS is used to time stamp seismic activity and to monitor position changes in sensitive physical formations such as volcanoes and earthquake fault lines.
GPS timing is important for telecommunications applications, particularly for mobile telephone networks. Synchronous technologies are much more efficient than asynchronous technologies but require a time source with appropriate accuracy, stability and reliability to operate effectively or at all, and GPS satellites can provide this. While ground‑based clocks are accurate enough for this purpose (especially with the availability of chip scale atomic clocks (CSAC)), the synchronisation of many such clocks is problematic. GPS allows the derivation of synchronised UTC time through resolving the signals from a number of atomic clock sources at known locations.
9. Financial Services
Global financial systems increasingly need precise timing systems to schedule and prioritise local and international money transfers, settlements and trades and to provide an audit trail for financial transactions. For example, the time signal provided by the atomic clocks on board the GPS satellites is used by financial institutions worldwide for providing date and time stamps for Electronic Funds Transfers. In some developed countries up to 80% of retail transactions involve either credit or debit cards. With millions of these transactions occurring every minute, a very high level of timing accuracy has become a critical component of financial trading networks.
10. Social Activities
Widely available, low-cost hand-held GPS receivers have enabled a numerous variety of social activities. The most ubiquitous application is in-car navigation, but there are dozens of other applications: GPS-based social networking, geotagging photographs, cross country cycling, hiking, skiing, paragliding, skydiving, geocaching, geodashing and other gaming activities.
11. Other Useful Information
Penn State University’s Geospatial Revolution Project
Penn State University in the US has produced a series of very informative videos of the use of geospatial information in modern economies – from producing highly accurate maps for land, sea and air navigation to more scientific uses such as mapping natural resources and monitoring agricultural production.
Obviously, GPS is a key component of nearly all geospatial information systems.
Acknowledgement: The information on this page is based, in part, on a report published by the Royal Academy of Engineering, London, March 2011 (www.raeng.org.uk/gnss).