Shaping Aviation Integrity Two RAIMs for Safety Apr 1, 2008 By: Todd Walter, Juan Blanch, Per Enge, Boris Pervan, Livio Gratton

Relative RAIM and absolute RAIM both enable an aircraft to raise a flag within seconds of receiving faulty data. This article evaluates the protection-level equations for both methods, and examines them in the light of GNSS constellations optimized for 24, 27, and 30 satellites.

Innovation: Good, Better, Best Expanding the Wide Area Augmentation System Jan 1, 2008 By: Timothy R. Schempp

While WAAS was already a much-valued addition to standalone GPS, significant improvements were made to WAAS over the past three years, including expansion of the reference station network and the commissioning of two new GEOs. 2008 will see even more enhancements. In this month's column, we take a look at WAAS's recent upgrades and take a peek into its future.

Approach with Precision Ground Augmentation Proves Out Sep 12, 2006 By: Tim Murphy, John Ackland, Tom Imrich, Tiffany Lapp, Roger Friedman

New ground-based augmentation systems at or near airports offer the potential of new or improved capabilities, as well as cost reduction for existing airspace system infrastructure. The authors tested a prototype using a multimode GPS receiver that converts differentially corrected signals to the airplane's instrument system, enabling more precise autolandings.

Troubleshoot Before Takeoff Modeling and Simulation for Navigation System Testing Sep 1, 2006 By: Curtis Hay, Colin Ford, Greg Gerten

Modeling and simulation, two separate but related activities conducted prior to flight tests of high-performance military navigation systems, can reduce costs, shorten timelines, and remove some uncontrollable variables from the process, to deliver more accurate, verifiable results.

EGNOS Takes Flight Aviation Trials Signal Benefits in Difficult Approach Environments Apr 1, 2006 By: Henk Veerman, Patrick Rosenthal, Olivier Perrin

Tests of the European Geostationary Navigation Overlay Service (EGNOS) indicate the system's future capabilities as a navigation aid for the aeronautical community, particularly in approaches to mountain-based airports and other challenging environments.

Guided to Gather — Toy Plane Upgraded with Telemetry Feb 1, 2006 By: Vanessa Espinar, Dana Wiese

GPS/INS and infrared optical sensors propel USGS's transformation of a remote-controlled one-quarter–scale recreational aircraft into a low-cost unmanned aerial vehicle designed for environmental particulate collection.

Robotic Fighters Coming in on GPS Jan 1, 2006 By: Lisa McAdam

A recent simulated test of military UAVs demonstrated one more envisioned GPS role in military operations. As part of the J-UCAS program, Northrop Grumman performed a test of simulated, simultaneous control of four X-47B UAVs on September 28, 2005, at the Naval Air Warfare Center Weapons Division in China Lake, California.