Col. Matthew Spencer on GPS modernization, OCX progress and the future of assured PNT.
As the global demand for resilient and assured positioning, navigation and timing (PNT) solutions accelerates, the United States Space Force (USSF) is adapting with a forward-looking strategy that integrates next-generation technologies while protecting the reliability of the GPS constellation. In a rare and candid interview with Inside GNSS, Colonel Matthew Spencer, Commander and Senior Materiel Leader for the PNT Systems Delta within USSF Space Systems Command, provided a detailed update on the GPS Operational Control Segment (OCX), M-Code deployment, alternate PNT initiatives, and the evolving role of commercial low Earth orbit (LEO) constellations in military navigation.
This in-depth conversation offers a unique and precise view of programs critical to national security and global stability.
A New Era: OCX Progress and the Shift to Integrated Mission Deltas
Spencer confirmed that the OCX program remains on schedule to support both GPS III and GPS IIIF constellations. OCX Block 1 and Block 2 milestones are advancing, providing enhanced command and control capabilities crucial for M-Code operations and overall mission assurance.
Highlighting organizational changes, Spencer discussed the realignment initiated by USSF Chief of Space Operations, General B. Chance Saltzman, to create Integrated Mission Deltas (IMDs) and System Deltas (SYDs). This reorganization empowers operators with early feedback mechanisms and smoother delivery pathways, an evolution designed to streamline mission effectiveness and reduce integration friction.
“By combining the acquisition and operational sides earlier in the lifecycle,” Spencer noted, “we’re able to deliver capabilities faster and more responsively to the warfighter.”
M-Code Activation: A Major Step Forward
One of the most significant milestones over the past year has been the activation of the M-Code signal across the GPS constellation. “Full global coverage is achieved with 24 active space vehicles in view at all times, enabling robust anti-jam and anti-spoof capabilities. With 25 space vehicles currently broadcasting the secure, high power M-Code signal, we’ve made this a reality,” Spencer said.
Early adoption of M-Code using existing ground systems is already underway, he said, providing critical lessons learned. Interest from allied nations is growing, with interoperability and
security continuing to be key priorities.
“M-Code provides a much more resilient signal environment,” Spencer explained. “And the work we’ve done with our allies shows that there’s strong interest internationally in leveraging this capability.”
Exploring the Frontier: LEO PNT Opportunities
Spencer also highlighted the potential of LEO-based navigation services. With commercial LEO constellations expanding rapidly, the military is studying how these systems could augment traditional GNSS.
Spencer described both the opportunities and challenges: “LEO offers higher received power and closer proximity, but the fast-moving satellites require more frequent signal reacquisition.” The Space Force, through AFWERX initiatives, has awarded $1.9 million across 20 companies to explore LEO PNT possibilities.
Spencer stressed that while commercial investment drives innovation, military requirements— including secure signal architectures—remain paramount.
Building a Resilient GPS Constellation
The Resilient GPS (R-GPS) initiative, which aims to provide resiliency to the GPS constellation with smaller, cost effective satellites, does not seek to replace GPS but to complement it, Spencer said. This parallel capability will help ensure military users maintain reliable navigation, even in degraded or contested environments.
“We don’t necessarily need centimeter-level accuracy for all use cases,” he said. “What we need is assurance and persistence.”
User feedback, he said, will continue to inform how alternate PNT solutions are fielded and integrated into broader operational concepts.
Spencer also addressed the accelerating tempo of space launches and its impact on acquisition models. Smaller, lighter satellites are now a priority to enable multiple payload deployments on a single launch vehicle—a key factor in building resiliency.
“Agility is essential,” Spencer emphasized. “We have to align acquisition timelines with the pace of launch opportunities and commercial innovation.”
The integration of resilient small satellites alongside GPS III and GPS IIIF platforms forms a layered architecture designed to maintain superiority across multiple domains.
Reverse Industry Days: A New Model for Collaboration
Another innovation championed by System Delta leadership has been Reverse Industry Days (RID), a format where military program offices solicit feedback directly from industry representatives.
“The goal is to foster real dialogue,” he said. “Industry insights help us refine our requirements and discover where disruptive technologies can make the biggest impact.”
Participation from across all services—Army, Navy, Air Force, Marines—ensures joint requirements are fully represented.
Interoperability, ALTNAV and Open Signals
International collaboration remains a bedrock principle of assured PNT strategies. Spencer noted that modern GNSS receivers increasingly support open signals from Galileo and Quasi-Zenith Satellite System (QZSS), alongside GPS. The Army’s Alternative Navigation (ALTNAV) program is also making strides, including work on L5-based resiliency.
Monitoring and guaranteeing quality of service for L5 signals is a major focus, he said, especially as dual-frequency, multi-constellation receivers become the norm.
“Assured PNT isn’t just about protecting our systems,” Spencer said. “It’s about ensuring interoperability and confidence in the entire GNSS ecosystem.”
Commercial LEO for Navigation: A Promising Horizon
Recent work by the University of Texas at Austin on using Starlink signals for navigation caught Spencer’s attention. While operational hurdles remain, he sees promise in leveraging commercial LEO constellations for military navigation, provided proper safeguards are in place.
“We have an opportunity to adapt commercially funded capabilities to meet military needs,” Spencer said. “Future receiver chips are likely to be LEO-capable by default.”
He highlighted the importance of supporting a robust commercial space sector, not only for communications but for navigation and timing resilience.
A Critical Time for PNT
Spencer’s remarks underscore a pivotal moment for military PNT. With OCX progressing toward full operational capability, M-Code becoming a reality, and alternate PNT solutions on the horizon, the U.S. Space Force is balancing the legacy of GPS with the innovation needed for future conflicts.
Despite the influx of alternate systems and complementary technologies, Spencer said, GPS remains the benchmark for reliability, integrity and consistency, and is still the gold standard.
“Our job is to protect, evolve and sustain GPS,” Spencer said. “At the same time, we must innovate to ensure that if GPS is ever denied, our forces still have trusted alternatives.”
