Utilising cell-tower triangulation as a reference point, differential global positioning (dGPS) helps improve both the speed and accuracy by which GPS-enabled devices communicate with satellites. Remote areas such as open water and rural lands are ideal locations for dGPS; the Australian government utilises the technology for both its coast guard and its land survey group. The government is further looking at the system to help improve the accuracy of readings by its air controllers.
The lack of complete accuracy in “standard” GPS communications can be traced to irregularities built-in to the satellite signals, as a product of military attempts to limit the usefulness of intercepted signals by encrypting the higher quality readings from readily available use. Known as selective availability, the system ensured primacy of military readings relative to those of civilian and non-regulated devices. As GPS evolved to allow full commercial uses, technologies, such as dGPS, were developed to help improve the accuracy of tracking devices. While selective availability was phased out in 2000, advances in dGPS had improved signals so that they were superior to standard open-reading tracking. Like many of the improvements in positioning technology, even as the system evolved beyond its initial military applications, civilian work-around technologies, when combined with advances in GPS hardware and software, paved the way for today’s pinpoint real-time accurate readings.
Today most GPS devices, especially mobile trackers, utilise dGPS to augment and improve their signals. In practice, various decentralised, ground stations are able to ping satellites. This data is then sent to GPS-enabled devices as far as several hundreds of miles away to correct any measurement areas emerging from distortions in the satellite signal. In practice, implementation of the technology has improved error rates in measurement by up to 66%, lowering the variance to less than 1/5 meter for each 100 KM the device is from the nearest station. Boats hundreds of miles away are able to ping land-based stations to help determine their location – as the technology improves, even boats far out at sea are able to communicate with the system, allowing fisherman, Coast Guards, cruise ships and recreational boaters alike to improve their navigation even under the most difficult of conditions.
Large GPS markets, from Australia to Europe to the United States have deployed their own dGPS networks to take advantage of the technology. These are known as ground-based augmentation networks (gBAS), and have been utilised extensively by coast guards across the world to improve tracking. The global expansion of dGPS is now a standard part of most GPS-enabled devices, lowering measurement errors and expanding the potential applications of GPS to new areas. Next-generation GPS devices continue to build on the gains of dGPS to further improve tracking, and provide precise readings in locations that were previously too remote to read GPS signals.