April 2006

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Over the last couple of years, a series of papers coauthored by members of the European Commission (EC) Galileo Signal Task Force have laid out elements of the frequency plan and signal structure: RF bands, lengths and types of codes, data rates, and so forth. What had remained missing were the Galileo codes and the navigation message structure.

Over the years, researchers have advanced the use of GPS receivers to measure water vapor content in the troposphere and model its effects on signal propagation. However, these techniques typically employ stationary GPS receivers. This column describes a method for measuring water vapor by GPS receivers on moving platforms and determining the associated atmospheric effects.