September/October 2008

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In July, a solar car racing team from the University of Michigan won the North American Solar Challenge (NASC) with Continuum, a sun-powered vehicle that averaged 46 miles per hour over the 2,400 miles from Plano, Texas, to Calgary, Alberta. It wasn't easy - GPS support vehicles used real-time simulations from a GNSS survey of the entire course to give the high-maintenance Continuum good advice - such as when to get out from under the clouds and back into the energy-producing sun.

Earlier this year, Galileo’s second experimental satellite reached orbit and began broadcasting a wide range of signals, including the first transmissions of the new composite BOC signal on the L1 frequency. In the first of three stories about Galileo's new signals in space, this article provides an initial report of GIOVE-B observations performed at the Chilbolton Observatory in the United Kingdom during May and June 2008.

The multiplex binary offset carrier (MBOC) was chosen as the optimal common open civil signal waveform at the L1 frequency for both GPS and Galileo, in large part because of its anticipated advantage in mitigating the effects of multipath (reflected signals). Turns out those expectations were correct, according to observations made by this team of researchers.

The prospects are good for carrier phase integer ambiguity resolution through double differencing signals from the first two Galileo experimental satellites (GIOVE-A and GIOVE-B), with accuracies at the millimeter level.

Once again the world is becoming a cauldron of grievances involving its most powerful nations, including the four primary members of the ICG Providers Forum.

The aerospace engineering professor has contributed to RAIM, GPS bistatic radar, satellite formation flying using GPS, GPS-based orbit and satellite attitude determination, and multipath mitigation —and to the future of middle school girls, who she encourages to stay tough about pursuing a rigorous scientific education.

Experts answer your technical questions about GNSS in this column coordinated by Mark Petovello, University of Calgary.

At its core, the performance of a modern GNSS system depends on the quality of its timing. Galileo’s GIOVE-B satellite is flying the first space-qualified passive hydrogen maser, and active hydrogen masers are part of the ground control segment that will generate Galileo system time. This column discusses the overall timing operation of the current Galileo architecture and points to the possibility of an even more accurate time source for GNSS systems in the future: optical frequency standards.

Montreal, Québec; U.S. Gulf Coast; the Moon; Worcester, UK; Mumbai; Beijing

Demoz Gebre-Egziabher reviews Paul D. Groves' new book

Phillip W. Ward reviews Jack K. Holmes' new book

Kyle O’Keefe reviews Alan Bensky's new book