GPS could have high accuracy and counter spoofing, if…

January 26, 2023  - By

It was 2018. Representatives from the European Space Agency were visiting Google headquarters in Mountainview, California.

Under discussion was Europe’s plans to introduce a high accuracy and authentication service to their Galileo satellite navigation system. Galileo would broadcast precise point positioning corrections on the E6-B band and provide users decimeter-level accuracy. They would also be including a navigation authentication message enabling receivers to distinguish genuine messages from deceptive ones sent by spoofers.

Wouldn’t Google like to incorporate these capabilities in future versions of Android phones?

The answer from Google Distinguished Engineer, Frank van Diggelen, was a resounding “yes.”


Technologically Possible

Van Diggelen also had another thought. It should be possible to deliver precise positioning corrections and authentication data via the internet. This could allow phones with an internet connection to access the services as well. With an app, older smartphones would be able to take advantage of the services, and it wouldn’t be necessary to add new hardware to new phone designs.

The next logical step was to establish an internet-based high accuracy and authentication service for the United States’ GPS. Unlike the newer European Galileo and Chinese Beidou systems, GPS satellites don’t have the ability to transmit data to improve accuracy and authenticate signals.

Technologically, providing corrections for high accuracy and authentication data to users via the internet is entirely possible, according to van Diggelen and other experts serving on the president’s Space-based Positioning, Navigation, and Timing (PNT) Advisory Board (PNTAB).

Yet a couple of process challenges in the United States could make establishing such a service difficult and might prevent its creation entirely.


Data collection and use not yet an official program

The first is related to the way in which the U.S. collects and handles real-time tracking data of the Global Navigation Satellite Systems (GNSS) ­­— GPS, GLONASS, Galileo, and BeiDou ­­— to derive corrections needed for a high accuracy service.

NASA’s Jet Propulsion Laboratory (JPL) operates NASA’s Global GNSS Network (GGN) of more than 60 stations around the globe, which provide their tracking data to JPL’s Global Differential GPS (GDGPS) System. The GDGPS System also has access to real-time tracking data from hundreds of additional sites, all of which track GPS and other GNSS. This allows the GDGPS System to generate precise corrections for the navigation messages of GPS and other GNSS. It also enables real time decimeter-level accuracy for positioning applications anywhere in the world. These corrections are provided to some government agencies and commercial entities on a reimbursable basis.

NASA’s GDGPS capabilities are not part of a formal, official government program, though. Rather they have grown organically as part of JPL’s efforts to push boundaries in scientific and engineering applications of GNSS, and its ability to take on work paid for by other agencies. Thus, GDGPS efforts lack a sufficient and established government funding line, formal programmatic tasking, and other structures and procedures needed to ensure its long-term viability as a government-provided service.

NASA and JPL officials recognized this and in 2020 established a working group to advise on how they should go forward. The following year that working group made several recommendations to NASA and the PNTAB. Among them were to establish a consistent level of NASA funding, create a Level-1 capabilities document for GDGPS, and start discussions towards an interagency memorandum of understanding (MOU) for long-term government funding.

At the same time, a PNTAB task force investigated the GDGPS activity and made recommendations to the PNTAB. They included: that NASA/JPL document GDGPS capabilities, including architecture, facilities, functions and products; that a stable government funding line for GDGPS be established; that a security review of GDGPS be undertaken; and to maintain GDGPS entrepreneurial aspects in pursuing multi-agency usage of its services.


Civil GPS rarely needs addressed

The second challenge to establishing high accuracy and authentication service for GPS appears to be the lack of an identified agent or mechanism within the federal government to do so.

Europe’s Galileo is a civilian system established and operated to support economic activity and development. The U.S’s GPS is run by the military.

First created to “put five bombs in the same hole,” it was built and run for years by the U.S. Air Force and is now the responsibility of the U.S. Space Force. Its primary mission is support of military missions and almost all funding comes through the Department of Defense (DOD).

Yet, indisputably, 99% of GPS users are not in the military and the system has become essential to most technologies and nearly every facet of the U.S. economy.

Official government policy has long recognized this, at least at the strategic level. Presidential policies issued in 2004 and in 2021 provided for improvements in functionality for civil users – as long as they were required by and entirely funded by a civil agency.

At a more tactical level, though, attempts to fund civil requirements have always faced great difficulty and rarely succeeded.* Mandates in presidential directives for civil signal monitoring, interference detection and mitigation, increased resilience, alternative PNT, and responsible use have all faced uphill battles and received little funding.

According to former senior government officials, this difficulty stems from civil GPS use being caught in a bureaucratic “Catch-22.”

On the one hand, executive branch policy dictates that funding for GPS capabilities and applications benefiting civil users must flow through the Department of Transportation (DOT). On the other, within government programming and budgeting circles, GPS is seen as an expensive military capability funded through the DOD. Requests for GPS and PNT-related funding through DOT are more difficult to explain and are easier to deny.

Compounding this difficulty is the lack of a clear and empowered national leader to advocate for a comprehensive and national approach to GPS and PNT issues and overcome bureaucratic snags.

As a result, the path forward for adopting the recommendation for a GPS high accuracy and resilience service is, at best, unclear.

Yet many on the President’s advisory board and in government are hopeful. “Establishing a high accuracy and resilience service for GPS is the right thing to do” said one. “We have all the pieces to make this happen. We just need to bring them together.”

And as one of the board members commented at the recent meeting, if the U.S. doesn’t do this “It stinks.”


Image: Slide from the National PNT Advisory Board Meeting in November 2022

*The exception to difficulties funding civil GPS-related capabilities is the Federal Aviation Administration’s Wide Area Augmentation System. It was established as the result of heavy lobbying by the airline industry, which continues to give it strong support.

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About the Author: Dana Goward

Dana Goward is president of the Resilient Navigation and Timing Foundation. He is the proprietor at Maritime Governance LLC. In August 2013, he retired from the federal Senior Executive Service, having served as the maritime navigation authority for the United States. As director of Marine Transportation Systems for the U.S. Coast Guard, he led 12 different navigation-related business lines budgeted at more than $1.3 billion per year. He has represented the U.S. at IMO, IALA, the UN anti-piracy working group and other international forums. A licensed helicopter and fixed-wing pilot, he has also served as a navigator at sea and is a retired Coast Guard Captain.