Global Navigation Satellite Systems Engineering, Policy, and Design
The usual formulation of position determination involves four unknowns: three physical dimensions (X,Y,Z) and the satellite-receiver time offset. In cases where we can observe five or more pseudoranges, one might well ask if the redundant pseudoranges could be used to check the consistency among the observations —the fundamental principle behind receiver autonomous integrity monitoring (RAIM).
By Alan Cameron
The recent GAO report and Government Oversight subcommittee hearing on GPS sustainability generated more heat than light, with some major news media outlets leaving the impression that the sky (or at least GPS satellites) would soon be falling.
Perhaps the only silver lining in the ensuing Chicken Little phenomenon was the crude measure it provided of just how familiar (but not necessarily knowledgeable) private citizens have become with GPS.
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The downloadable PDF (above) contains bonus material not available in the print edition.
This column continues an exploration of possible use of the C-band radio frequency for GNSS navigation. Part 2 focuses on C-band signal design in the context of non-interference with other services in nearby RF bands, as well as user equipment design and performance.
Figure 1: Indoor positioning configuration with switching repeater with multiple re-radiation antennas.Q: What is GNSS repeater-based positioning and how is it different from using pseudolites?
A: A GNSS repeater is just like a cellular phone repeater that is used to boost the cell phone reception by using a reception antenna, a signal amplifier and an internal rebroadcast antenna. In contrast to cellular broadcast stations, GNSS repeaters are much smaller and often installed inside buildings with an external reception antenna collecting the satellite signals.
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Figure 1
The downloadable PDF (above) contains bonus material not available in the print edition. Appendices and other information on this subject is available at the bottom of the page.
The current version of the master GPS Interface Specification document (IS-GPS-200 Rev D March 2006) contains a new dual-frequency ionosphere correction algorithm that is to be used with the modernized GPS space vehicles (SVs) and their next-generation modernized GPS signals.
IFIS 2010 will be held in Beijing from June 21-25.
The theme is “Improving Flight Inspection for NextGen Technology.” Flight inspection is presented with a host of opportunities and challenges as Satellite-based Navigation and Performance Based Navigation open the way to even more advanced methods of airspace navigation.
By Inside GNSS
The European Navigation Conference 2009 is now underway at Parthenope University in Naples, Italy.
In the opening session on Monday, May 4, the chief engineer for the GPS Wing told the audience that the new L5 demonstration signal transmitted by GPS IIR-20(M) had been experiencing problems and apparently interfering with L1 and L2 legacy signals. Lt. Col. David Goldstein said the Air Force will not launch any more satellites until the cause has been discovered and fixed.
By Inside GNSS
China intends to finish their Beidou Navigation Satellite System (BDS, formerly known in English as "Compass") by 2020. When complete, the constellation will will consist of 35
satellites: 5 geostationary orbit (GEO) satellites, 27 in Medium Earth Orbit (MEO) and 3 in Inclined
Geosynchronous Orbit (IGSO).
BDS began providing services to civilian users in China and surrounding areas in the Asia-Pacific in December 2012.
By Inside GNSS
The 8th navigational symposium on marine navigation and safety of sea transportation will be held at Gdynia Maritime University in June.
Scientists and navigation professionals from a number of countries will share their knowledge, experience and research results in all aspects of navigation, safety of navigation, and sea transportation.
By Inside GNSS
The 15th Ka and Broadband Communications, Navigation and Earth Observation Conference will be held in September at the "T" Hotel in Cagliaria, the capital of Sardinia.
The Italian Space Agency (ASI) conference originally covered satellite communications at 20-30 GHz and higher frequencies. In recent years, it has been expanded to include satellite
broadband communications at all frequencies and satellite-aided navigation.
The event includes the 7th Broadsky Workshop, which will focus on the escalating problems of space debris.
ESRI UC, the largest conference for GIS users, developers, integrators and suppliers will take place at the San Diego Convention Center in San Diego, California USA from July 13 to July 17 2009.
The conference registration deadline is May 22, 2009.
The educational side of the event includes breakout conferences on GIS and
remote sensing, homeland security, survey and engineering, and
education.
For a complete list of session tracks go to:
By Inside GNSS
The mobile industry’s largest exhibition will be held at Fira Montjuïc in the center of Barcelona, Spain February 16-19 2009. The event features 50,000 attendees, presentations and networking events, awards for best technology, keynotes by noted corporate leaders, an associated film festival, and more.
The 2009 keynoters are:
Cesar Alierta Chair and CEO, Telefonica
Jon Fredrik Baksaas, President and CEO,Telenor
Steve Ballmer, CEO Microsoft
The EGU General Assembly 2009 will be held at the Austria Center Vienna from April 19 to April 24. The official language is English and scientists from all countries are welcome.
Live press conferences are available here Monday through Thursday: http://www.webstream.at/egu
Please check the Press Conference Program for further details.
