As cell phones move into the next generation called Long-Term Evolution (LTE), also sometimes called 4G, and the methods of wireless transmission change, so too must the methods of providing location information over those new wireless interfaces. LTE Positioning Protocol (LPP) and Secure User Plane Location (SUPL) 2.0 and 3.0 are the key players in this new picture.
Geodesy is a suite of powerful Earth-observation techniques, associated methodologies, and analysis tools that today are making a vital contribution to science and society. Yet geodesy is not a new, child-of-technology sciaence. It dates back hundreds of years — some would claim thousands of years, and that the ancient Greeks and other pre-Christian cultures shaped its direction. This is illustrated by its classical definition as the science of measuring and mapping the geometry, orientation in space, and gravity field of the Earth; these days we also include their variations over time. At a practical level, geodetic practice forms the foundation for surveying, navigation, and mapping, and the digital datasets underpinning these activities.
On November 1, 2010, China’s state news agency reported that the sixth Compass satellite was launched from the Xichang Satellite Launch Center. This was the fourth Compass satellite put into orbit this year, following launches in January, June, and August. Joining the United States, Russia, and the European Union, China is deploying is own global navigation satellite system of five geosynchronous satellites, 27 in medium Earth orbit (MEO) and three in highly inclined geosynchronous orbits (IGSO). Sometimes referred to as Beidou-2, Compass is a global RNSS (radio-navigation satellite system) that broadcasts one-way precision time signals to enable receivers to calculate their position. An earlier Chinese satellite navigation system, Beidou-1, was an RDSS (radio-determination satellite system) that provided regional coverage and required two satellites to get a position fix using two-way communications with a centralized ground station.
In 2009, a Government Accountability Office (GAO) report claimed that the GPS constellation was extremely vulnerable to failure, and a recent September 2010 GAO follow-up continues to make that assertion. In this article, we present the technical data to contradict some of the GAO report conclusions.
The new European Positioning, Navigation, and Timing (PNT) Industry Council (EPIC) will be a forum for organizations with an interest in all PNT systems including Global Navigation Satellite Systems (GNSS). EPIC shall serve as an information and distribution portal between all stakeholders in the PNT community. Its mandate includes all GNSS constellations and related augmentation systems worldwide, both operational and in development/modernization.
As today’s handsets and consumer devices become more sophisticated, manufacturers continue to incorporate more and more functionality into a small and sleek form factor. Today’s range of smartphones incorporate voice and data transceivers, GPS, Bluetooth, Wi-Fi, cameras, music, touchscreen interfaces, compasses, motion sensors, cameras, storage cards, and many other technologies. Free turn-by-turn navigation services, such as offered on Google Android phones and iPhones, have created a compelling reason for many of us to own a GPS-equipped smartphone.
Few outside the position, navigation, and timing (PNT) community will also recall that the day before the 9/11 attacks, the U.S. government released a landmark document that described the vulnerabilities of services provided by GPS to disruption, whether by attack or inadvertent interference. The Department of Transportation Volpe Center’s GPS vulnerability assessment recommended that services utilizing GPS-provided PNT seek alternative sources of these services. What decisions and actions have the findings and recommendations of this report promoted? The answer is most disturbing.
I started my relationship with GNSS and Moore’s Law in 1985, writing software for GPS tracking loops on the Advanced Range Instrumentation Aircraft program at the Applied Physics Laboratory of Johns Hopkins University for the U.S. Air Force. The project’s purpose was to navigate a large jet to accurately fly a pattern to drop buoys into the ocean. That receiver had seven circuit boards (six trackers and one navigator) mounted on a VME backplane in a 19-inch rack mount in the back of a C-130, and was about the size and weight of suitcase.
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