Perhaps for the first time in the nearly 40 years of satellite navigation, all four GNSS programs and regional systems appear to have firm — if not always unencumbered — development paths ahead of them.

GPS, GLONASS, Galileo, Compass/Bei- Dou, Japan’s MSAS and QZSS, and India’s GAGAN and IRNSS systems are bringing new or modernizing elements into the world. Key program enablers — such things as budgets, satellite construction, launches and launch vehicles, new signal designs — all appear favorably aligned.

Despite these encouraging conditions, however, many unknowns remain ahead: technical and political challenges on the one hand, and opportunities to optimize potential inter-system synergies on the other.

To help assess and sort out the issues surrounding GNSS modernization, we called on the expertise of Christopher Hegarty, director for communication, navigation, and surveillance engineering and spectrum at The MITRE Corporation.

Hegarty played an instrumental role in the selection of the frequency for the GPS third civil signal (L5), co-led the development of the specification for this signal, served on a U.S./European technical working group that helped produce agreement on a common L1 civil signal design, and has also been an active participant in U.S. bilateral discussions with all other foreign satellite navigation service providers.

His current work focuses primarily on aviation applications of GNSS and on issues of GPS compatibility and interoperability. Hegarty is coeditor of Understanding GPS: Principles and Applications, Second Edition (Artech House, 2006).