By: J. David Grossman, Executive Director, GPS Innovation Alliance Sept. 23, 2020
Do you remember the first time you experienced the transformational benefits of GPS? For millions of Americans, a portable in-car navigation unit offered an introduction to GPS, at a time when there were no smart phones or watches. Over the past two decades, GPS technology has improved substantially resulting in devices that are smaller, more accurate and efficient. But there is another part to this success story that has largely been invisible to the end user, and that is the effort to modernize the GPS constellation and ground control. Thanks to the U.S. government’s sustained investment in modern satellites, GPS users across a wide range of industries including agriculture, aviation, construction and defense, have counted on GPS to continuously deliver a signal with a high degree of accuracy, reliability, and resiliency.
Today under the leadership of the U.S. Space Force, new GPS III satellites, built by Lockheed Martin and combined with a modernized ground control, are providing three times greater accuracy for the benefit of all users and up to eight times improved anti-jamming capability benefiting military users. This exciting development has already resulted in the launch of three GPS III satellites, with a fourth expected to take off later this month, and many more in the months and years ahead.
Among the benefits of the new generation of GPS satellites is the addition of the L1C, L2C and L5 civil signals. The newest of the signals, L1C, was designed with a focus on international participation because of its interoperability with other systems, such as Europe’s Galileo. L1C interoperability means that users receive signals from many more satellites including both GPS and Galileo constellations. L1C’s revolutionary signal structure provides greater robustness, higher accuracy in multipath, and features for a range of applications from low-cost consumer devices to high-end professional devices. L1C also delivers greater than 40 percent more power than the L1C/A signal used around the world for decades.
The L2C civilian GPS signal was designed specifically to support commercial positioning, navigation and timing (PNT) services, such as those used for agriculture and surveying. Dual-frequency receivers can utilize L2C with any other GPS civil signal to negate ionospheric errors and boost accuracy. Civil dual-frequency GPS receivers can experience the same accuracy as the military, or better if used with special phase-tracking techniques. In sum, L2C provides fast signal acquisition, improved reliability and enables better accuracy.
The GPS L5 signal was carefully coordinated with the Federal Aviation Administration (FAA) and international GNSS systems to ensure maximum compatibility across satellite constellations, thus enabling the ability to usher in a new generation of certified safety of life GNSS avionics. The first batch of 10 GPS III satellites is expected to bring the number of L5 capable GPS satellites to 22 by end of FY2026. Given that the L5 signal is located in the protected ARNS band, the dual frequency L1-L5 GPS signal combination is set to provide unprecedented accuracy, integrity and continuity in support of Global LPV-200 capabilities (instrument-only guidance all the way down to 200 feet above the runway) for a variety of airborne platforms across a range of markets.
GPS modernization has also led to the introduction of M-Code, an advanced, new signal designed to improve anti-jamming and anti-spoofing, as well as to increase secure access to military GPS signals for U.S. and allied armed forces. In GPS-denied environments, M-Code reduces the jamming radius, giving military planners and targeteers options to minimize or avoid collateral strike damage. Today, there are 22 M-code satellites currently operational, with two additional satellites expected to be on orbit by early 2021, culminating in a total of 24 M-code capable satellites next year.
Finally, GPS modernization will ultimately deliver a new ground control segment known as the Next Generation Operational Control System (OCX). In the interim, the current GPS ground control system, the Operational Control Segment (OCS), has been upgraded to control both the more powerful GPS III satellites and the legacy satellites together in the GPS constellation, as well as to address expanding cyber threats. To ensure the continued modernization of GPS, GPSIA offers the following policy recommendations:
Passage by the U.S. House of Representatives of H. Res 219, a bipartisan resolution introduced by Reps. Dave Loebsack (D-IA) and Don Bacon (R-NE) which recognizes the contributions made by the men and women of the U.S. Air Force (now Space Force) who are responsible for operating and maintaining the GPS constellation and affirming the importance of continuous availability, accuracy, reliability and resiliency of the GPS constellation. A companion resolution, S. Res 216 passed the U.S. Senate by unanimous consent in May 2019.
Launching new GPS satellites based solely on sustaining the existing constellation is not a cost-efficient practice. GPSIA urges the DoD to consider transitioning its space segment from a ‘launch-on-need’ profile to one of ‘launch-on-schedule.’ Doing so would not only expedite the benefits of a modernized GPS constellation, but also could save taxpayer dollars.
Ensure that Lockheed Martin’s M-Code Early Use (MCEU) upgrade, which will enable OCS control of M-Code, remains on track to be operational in November of this year.
The future of GPS remains bright. Investing in a modernized GPS constellation and ground control ensures the GPS success story continues for many years to come.