By Dr. Clark Taylor
ANT Center Director
Air Force Institute of Technology

Since becoming operational in the early 90s, the Global Positioning System (GPS) has helped enable several important military and civilian technologies, including autonomous vehicles, precise munitions, enhanced collaboration between military units, distributed, precise time synchronization, and many more. Not only does GPS enable all these applications, but the cost required to purchase a GPS receiver is extremely low (as evidenced by their inclusion in cell phones and many other consumer devices.) Therefore, GPS has been a critical enabler of many different applications, from cell phones, to civilian flight, to military missions.

Unfortunately, while GPS is immensely successful in providing position and timing information worldwide, like all radio frequency (RF) signals, GPS signals can be jammed (to prevent GPS from being used) or spoofed (to fool someone into using false signals.) Non-military examples include the truck driver who didn’t want their company to track them, so they bought a small GPS jammer. Or, fans of the Pokémon Go game that started to spoof locations so they could get points in the game, without actually visiting the locations required.

While these examples may sound innocent, the effects of jamming and spoofing can be very costly. For example, the truck driver with a jammer unfortunately drove near the end of the Newark runway, causing disruptions to air traffic. In a military scenario, GPS jamming or spoofing can have even more significant consequences.

The Autonomy and Navigation Technology (ANT) Center at AFIT has spent over a decade researching and implementing techniques to help alleviate this strategic weakness. The ANT Center has three main research thrusts: (1) autonomy and cooperative systems, (2) non-global navigation satellite systems (GNSS) (GPS plus other countries navigation systems) navigation, and (3) improved GNSS navigation.

Starting with the third thrust, we are continually developing, testing, and advancing techniques to ensure that GPS can be available and trusted, even in environments where adversaries may be trying to deny, degrade, or spoof the GPS signals. The second thrust looks at how we can obtain positioning and timing when GPS is not available. This can be done using ranging radios on the ground, using cameras on-board aircraft to localize where the aircraft is, or utilizing the Earth’s magnetic anomaly field to self-localize a moving object. (While there are many other techniques, both previously explored and yet to be investigated, we have limited space in this newsletter.) The first thrust, enabling autonomy, with or without GPS, is key for maintaining the U.S. competitive edge over our adversaries. One example discussed in this newsletter is enabling autonomous air-to-air refueling, even when GPS is denied.

With the high-quality students that come through AFIT, generous funding from our sponsors, and the great work of contractors and faculty in the ANT Center, we have been able to make significant strides towards lowering our overall dependence on GPS without interference.