Johns Hopkins APL-Developed Target-Tracking Tech Drives Critical Defense Systems

When it comes to national defense, technology can’t stand still.

For more than 15 years, a capability for tracking multiple moving targets has been powering critical sea, land, and air defense systems. Designed by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and known as Precision Engagement of Moving Targets, or PEMT, the system uses an ingenious blend of innovations in data fusion; computational resource management; and intelligence, surveillance, reconnaissance, and targeting (ISR&T) and continues to meet evolving mission needs.

“PEMT is a capability that APL has developed over time and continues to invest in and improve,” said Francesca McFadden, who manages the ISR Processing and Fusion program in APL’s Precision Strike Mission Area. “It’s been deployed in dozens of programs across multiple warfighting and intelligence domains, but there’s significant potential for broader adoption across an even wider range of missions.”

PEMT is a longtime staple of the Air Force’s Dynamic Time Critical Warfighting Capability (DTCWC) platform, which fuses a variety of sensor inputs to detect, locate, track, classify, and report on high-value, time-sensitive, relocatable, and moving land and sea surface targets.

PEMT was first integrated into DTCWC in 2009, with roots reaching back to internal APL efforts in the early 2000s.

The Changing Tactical Landscape

The end of the Cold War and beginning of conflicts in the Middle East triggered a shift in the use of ISR&T systems, which collect and process various kinds of data — including electronic signals, network traffic, imagery, video, and spectral data — from a variety of sources, such as satellites, manned and unmanned aircraft, aerostats, and human intelligence operators. Whereas ISR&T systems were at one time used primarily to inform high-level strategic and operational decision-making, newer conflicts demanded more tactical use, where speed and agility are crucial.

Meeting those needs presents a significant challenge. ISR&T systems are effectively walled off from one another in separate processing chains, sequestered by data type, application, military domain, or access levels. Moreover, the sheer volume of data they handle often results in bottlenecks that impact system performance. These problems have to be solved for ISR&T systems to achieve their full tactical potential.

APL invested in multiple efforts to do just that, developing two distinct but interrelated solutions. The first, upstream data fusion, entails the processing, exploitation, and fusion of data from a wide array of sensors as close to the source as possible. The second, closed-loop collaborative ISR, involves connecting and synergizing three parts of ISR&T systems that had not previously operated in conjunction with one another — the sensors collecting the data, the automated fusion processing of the data, and the tactical commanding of the sensors.

These efforts came together, in 2006, with the beginning of PEMT.

Real-Time Data Fusion

Led by Andrew Newman — who conceived the capability — and using Independent Research and Development (IRAD) funding, the APL team combined the closed-loop collaborative ISR and upstream data fusion concepts into a single capability, and added algorithms to manage the computational resources.

“Nothing like this had been done in practice in broad-area, multi-domain military ISR&T before then,” Newman said. “Some programs did bits and pieces, but there was no holistic realization of a closed-loop ISR&T system for the missions of interest that could process realistic volumes of actual data.”

That first IRAD project led to several efforts to develop, refine, and expand the core concept, with the goal of not only meeting existing government needs but also anticipating missions at all classification levels.

“Our vision was to achieve what we call all-source data fusion — the ability to receive and combine data from any available sensor modality, asynchronously and at whatever rate it’s provided, and dealing with all of the complexities that come with that,” said Jon DeSena, PEMT’s technical director and lead developer. “That philosophy has been one of the keys to our success and is why PEMT continues to expand and be applied to new use cases.”

In 2009, APL began integrating the system into DTCWC, modernizing the program’s software design and implementing the operational concept at scale. Since then, the Navy, the Air Force, the Army, and the Marines have used PEMT to track multiple targets in missions at sea, on land, in the air, and — experimentally — in space.

New Applications

APL continues to partner with the government to apply PEMT to new domains, missions, and use cases — including the defense industry, explained PEMT developer Tim Crowe.

“PEMT takes APL-developed target-tracking, collaborative sensing, and resource management algorithms and combines them into a high-performance implementation that’s highly adaptable to different use cases,” Crowe said. “The ultimate goal is to have PEMT accessible on a website open to validated users, so that anyone in the industry can apply it to their own needs.”

Brian Geesaman, mission area executive for Precision Strike at APL, said the effort demonstrates the Laboratory’s ability to make critical contributions to the national defense across multiple warfighting domains.

“PEMT exemplifies how the Laboratory delivers incredible value across government sponsors, deftly balancing the transition of capability into new domains with the immediate need to provide a decisive advantage to our warfighters,” he said.