High-Intregity GPS, or iGPS, Advances

July 28, 2009

Iridium and Boeing have demonstrated capability steps along the way to the High Integrity GPS program for the U.S. Naval Research Laboratory. The companies completed an enhanced narrowband software modification to computers on Iridium satellites, enabling second-generation GPS-aiding signals to be broadcast through the entire Iridium constellation. The GPS-aiding signals will provide appropriately equipped warfighters significantly improved capabilities for quickly locking on and maintaining a GPS signal, even while operating in restrictive environments and under jamming. They also demonstrated acquisition of a GPS signal under substantial jamming while moving in a vehicle.

On July 13, Iridium Satellite LLC announced that, in conjunction with Boeing, the companies had achieved two milestones in development and demonstratation of capability enhancements to the High Integrity GPS (iGPS) program for the U.S. Naval Research Laboratory.

Completion of an Enhanced Narrowband (ENB) software modification to computers on Iridium satellites enables second-generation GPS-aiding signals to be broadcast through the entire Iridium constellation. These broadcasts will enable rapid, more accurate GPS position fixes than are available with current technology, according to the companies The GPS-aiding signals will provide appropriately equipped warfighters significantly improved capabilities for quickly locking on and maintaining a GPS signal, even while operating in restrictive environments such as urban areas, forests, mountains and canyons, as well as under enemy jamming attempts or amid battlefield radio frequency noise. This will provide warfighters with improved GPS anti-jam and time-stability transfer capabilities.

Secondly, the companies demonstrated to their government sponsor the acquisition of a GPS signal under substantial jamming while moving in a vehicle.

The iGPS principle uses satellite signals from the Iridium low-Earth orbiting (LEO) satellite communications system and GPS mid-Earth orbit navigational satellites. Iridium provides a high-power signal and rapidly changing ground track to accelerate an initial position fix by users. The GPS system provides navigational data in time, location and velocity. The result is an augmentation to GPS that provides iGPS receivers with improved navigation, higher signal integrity, precision accuracy and more jam-resistant capabilities. iGPS also has the potential to provide geographic positioning data to within centimeters, an improvement over current meter-level standalone GPS.

The iGPS team includes Iridium, Boeing Phantom Works' Advanced Network and Space Systems, Rockwell Collins, Coherent Navigation and experts from academia.

In March 2007, the Boeing Co. announced concepts for combining the GPS network with the Iridium low-earth orbit telecommunication network to improve accuracy, and signal acquisition in urban environments. Boeing executives delivered the briefing at the National Space Symposium for Pentagon and industry officials. "In any event, this would not obviate the need for GPS upgrades in any way," said retired Maj. Gen. Craig Cooning, vice president and deputy general manager of space and intelligence systems at Boeing. "What it does represent is an elegant solution for augmentation of GPS."

Iridium is a constellation of LEO communication satellites originally developed by Motorola Inc. in the late 1990s. When the system proved uneconomical, it was almost de-orbited early in the decade, until the Defense Department and private investors put in new money to keep the systems in orbit. According the Boeing statements in 20008, the Iridium constellation would have to be replenished in order to support the IGPS concept, but an upgrade of the system would be necessary in any event by 2014.