Innovation: Making a Difference with GPS Time Differences for Kinematic Positioning with Low-Cost Receivers May 1, 2008 By: Johannes Traugott, Dennis Odijk, Oliver Montenbruck, Gottfried Sachs, Christian Tiberius

One of the difficulties with RTK-style positioning is resolving carrier-phase ambiguities. If you time-difference sequential carrier-phase measurements, the ambiguity actually disappears, and you can determine accurate relative positions using time-differenced carrier-phase measurements. But there are some caveats.

Innovation: Tsunami Detection by GPS How Ionospheric Observations Might Improve the Global Warning System Feb 1, 2008 By: Giovanni Occhipinti, Attila Komjathy, Philippe Lognonné

Recent investigations have demonstrated that GPS might be an effective tool for improving the tsumani early-warning system through rapid determination of earthquake magnitude using data from GPS networks. A less obvious approach is to use the GPS data to look for the tsunami signature in the ionosphere.

Innovation: Brainy Positioning Processing GPS Data with Neural Networks Sep 1, 2007 By: Rodrigo F. Leandro, Carlos A.U. da Silva, Paulo C.L. Segantine, Marcelo C. Santos

Primarily developed for computing applications, such as pattern recognition, neural networks have been adapted for use in several fields of science, including geodesy. Those adaptations are needed because usually the situations and problems encountered in computer science are different from those in other fields. Geodesy is no exception.

Innovation: Network RTK Getting Ready for GNSS Modernization Apr 1, 2007 By: Herbert Landau, Xiaoming Chen, Adrian Kipka, Ulrich Vollath

An innovative filter technique significantly extends the number of reference stations that can be supported for network RTK positioning under modernized GNSS.

Innovation: Stochastic Models for GPS Positioning — An Empirical Approach Feb 1, 2007 By: Rodrigo F. Leandro, Marcelo C. Santos

When processing GPS data, we should not only try to model the deterministic part of the measurements; we should also try to account for their stochastic behavior, which is possible through use of the covariance matrix. Here, the authors present an empirical approach for building the covariance matrix of observations, with the ultimate goal to improve the quality of GPS data processing.

Innovation: Phase Wind-Up Analysis Assessing Real-Time Kinematic Performance Sep 1, 2006 By: Don Kim, Luis Serrano, Richard Langley

A circularly polarized antenna's phase depends directly on the antenna's orientation with respect to the signal source. As a result, the observed carrier phase depends on the relative orientation of the transmitting and receiving antennas as well as the direction of the line of sight between them. Changing the receiver antenna orientation changes the reference direction and thus the measured phase.

PDF: The OpenSource GPS project has developed an economical hardware and software platform specifically for educational purposes. In this month?s column, two of the project?s leaders, present part one of a two-part article on the project. This month, they will discuss the hardware component, built around the Zarlink GP2015/GP2021 chipset.