Ensuring navigation in GPS-denied environments
Global militaries are leveraging multiple technologies and creating augmented solutions to ensure navigation in GPS-denied environments. In this QandA with Troy Brunk, vice president and general manager of Communication, Navigation and Electronic Warfare Solutions for Rockwell Collins Government Systems, he discusses this trend, the history of GPS technology, improvements in Galileo Global Navigation Satellite System (GNSS) solutions, leveraging M-code, and more. Edited excerpts follow.
BRUNK: Rockwell Collins built its own GPS receiver and became the first company to receive the signal that was sent from the world’s first GPS satellite in 1977. Soon after, [the company] won the Navstar GPS user equipment contract. Since then, Rockwell Collins has continued to pioneer advancement in military GPS. In 1994, a secure, military-grade Precision Lightweight GPS Receiver (PLGR) was first fielded that provided warfighters a tactical navigational advantage on the battlefield. In 2012, [the company] began work on the Military GPS User Equipment (MGUE) program to develop an M-Code [Military-Code] receiver, which operates using a more powerful signal that’s resistant to cyber threats. And in 2014, Rockwell Collins developed a prototype to track a satellite in the GNSS that was being created by the European Union to provide global coverage for its nations.
MIL-EMBEDDED: What’s being done to ensure navigation in GPS-denied environments?
BRUNK: The U.S. and other militaries are pursuing augmented solutions, including improved antijam and antispoof for GPS as well as the integration of non-GPS sensors and infrastructure to enable the delivery of Positioning, Navigation, and Timing (PNT) information in unfriendly environments. [To solve the GPS-denied problem we] also leverage the latest technologies in areas such as networked navigation, optical/radar tracking, pseudolites [“pseudo-satellites,” most often small transceivers that are used to create a local, ground-based Global Positioning System (GPS) alternative], and map matching.
This year we delivered our latest-generation Digital GPS Anti-Jam Receiver, DIGAR, to the U.S. Air Force Special Operations Command. This provides airborne antijamming capabilities with [more than] 10,000 times the resistance over the previous model. (Figure 1.)
MIL-EMBEDDED: How are reduced size, weight, and power (SWaP) requirements impacting GPS designs? Any tradeoffs with smaller tech?
BRUNK: The primary tradeoff is very low-SWaP applications will have reduced options to augment GPS for operation in unfriendly environments.
MIL-EMBEDDED: How is GNSS being improved? What are the biggest tech requests for Rockwell Collins when it comes to receivers for GNSS?
BRUNK: Improved assurance (access and integrity) is being requested more from our markets. We have several technologies available to provide significant assurance improvements. These include GNSS software enhancements, antijam antenna technologies, alternative (non-GNSS) navigation sensors, and alternative infrastructure technologies like pseudolites.
MIL-EMBEDDED: What are the key capabilities of your NavHub system and how does it leverage M-Code?
BRUNK: NavHub is an augmented GNSS that allows multiconstellation GNSS as well as inertial sensors to provide improved assurance. Key capabilities of NavHub would include positioning for M-Code, GPS-denied navigation and timing on ground vehicles, and I/O compatibility with legacy GPS solutions.
MIL-EMBEDDED: GNSS is vulnerable to low-power signals. In mission-critical battlefield situations where navigation must work, what alternatives are being used? And are they being combined with GPS as backup?
BRUNK: Several augmentations to GPS are being investigated and implemented to enable continuous delivery of high-assurance PNT. Rockwell Collins works to deliver solutions so warfighters can navigate with confidence in demanding combat environments and that of course involves making sure alternatives exist as a backup.
MIL-EMBEDDED: How big of a problem is jamming/spoofing, and what can you do about it?
BRUNK: Recent innovations have significantly advanced technology to improve the antijam and antispoof performance of our GPS receivers. These include proprietary GNSS software enhancements, advanced antijam antenna technologies, and integration of non-GNSS sensors.
MIL-EMBEDDED: In terms of secure GPS technology, how do you leverage encryption in your systems?
BRUNK: Military GPS signals are inherently encrypted and we implement the proper processing capability to take full advantage of that encryption. The new military M-Code is an encrypted code being rolled out by the U.S. military as the next generation of GPS, and Rockwell Collins has extensive work underway to transition our products to it for improved security and performance.
MIL-EMBEDDED: In the future, what disruptive technology/innovation do you expect to be a game-changer in the GPS/GNSS/navigation world?
BRUNK: We believe size and cost reductions in technologies that enable high-assurance PNT at higher and higher levels of performance will enable more platforms to have more reliable PNT across more of their missions. Non-GNSS sensor technologies continue to advance in SWaP improvements, sensor fusion techniques continue to improve, and alternative sensors that can navigate with alternative infrastructure or without infrastructure continue to develop and provide viable navigation capability.