November/December 2008

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The clock is running out on the administration of George W. Bush, which may go down in history as one of the United States’ most unpopular presidencies. But that unpopularity and relief at the arrival of a new administration masks eight years of significant change in the world of GNSS. This includes substantial progress in modernizing GPS and driving its widespread acceptance into all regions of the world, as well as the rise of other GNSS systems. In this analysis, Inside GNSS editor Glen Gibbons reviews the key changes in GPS wrought during the Bush administration and examines the prospects for the system under an Obama presidency.

Authors from France’s national meteorological agency and the French space agency describe techniques and applications that predict weather and monitor climate change using the behavior of GNSS signal propagation through the Earth’s atmosphere.

With increased computer power, receiver designers can now make use of complex algorithms and computationally intense solutions to reduce the bad effects of multipath – reflected signals – on GNSS equipment. The authors describe how certain multipath mitigation techniques based on principles of maximum-likelihood estimation can improve receiver performance. 

Formation flying can create large spaceborne instruments by using several smaller satellites in close formation — to the considerable benefit of many scientific missions planned in the near future. However, the concept requires very accurate relative positioning and orientation of the spacecraft, which can be accomplished at lower altitudes using GNSS techniques and at higher altitudes by employing a similar approach to relative positioning using RF measurement techniques.

The parting regime was an administration of people — people who kept working away through all the bad days and dark hours. Just folks who got up each day and did the best they could with what they had and where they were...

“For how long can a satellite almanac be used?” Ted Driver, Analytical Graphics, Inc. answers.

This issue it's a bridge over the world's fifth largest river system, an endurance test for shorebirds, 9-1-1 glitches, GLONASS and Compass launches and a new tool for castaways.