Navy surveillance planes and Air Force fighters jets operate in combat with the clear, simple requirement of needing to know where they are in relation to one another, enemy forces and surrounding terrain. It’s called Positioning, Navigation and Timing (PNT), a term connoting the key variables needed in warfare missions, yet it is something which can easily be attacked by enemies.
This reality is why the Pentagon continues to work vigorously to harden GPS networks and also fortify alternative PNT technologies to ensure functionality in the event of jamming or enemy attack.
With this in mind, the Pentagon and industry are working on a number of systems intended to solidify and further enable PNT. Northrop Grumman is developing an emerging navigation capability that will integrate state-of-the art inertial technology along with enhanced timing and modernized GPS M-code signals to strengthen GPS and PNT.
The technology, called the Embedded Global Positioning System/Inertial Navigation System-Modernization (EGI-M), is now being integrated into Navy E2D Hawkeye surveillance plane and Air Force F-22 stealth fighter jet. The system just completed what’s called a Critical Design Review, a key step prior to detailed design and development of production hardware and software leading to aircraft integration.
The technical specifics of how EGI-M achieves its PNT data are indeed quite complex, as they pertain to advanced scientific principles, software and computer technology able to calculate essential “measurements” of movement, acceleration and position changes. White explained that “gyroscopes and accelerometers” can track movements of an object according to certain established laws of physics.
Brandon White, Vice President, Navigation and Positioning Systems, Northrop Grumman, told The National Interest in an interview that newer PNT uses what’s called Fiber-Optic Gyroscope, a technology which operates in accordance with established scientific phenomena regarding the effect of angular rotation on counter-propagating beams of light. A navigation system based on inertial measurements from gyroscopes and accelerometers can either start with, supplement and solidify a GPS signal or alternatively function independently as needed, White said.
The inertial sensing, White told me, is established by how “the gyro can measure a difference in the phase of light propagating through an optical fiber coil.” Interestingly, the scientific process, which relies upon a famous concept called the Sagnac effect, includes a way to assess the rotations generated when two beams of light are injected into the same fiber in opposite directions, according to a 1996 essay called “The Fundamentals of The Interferometric Fiber-Optic Gyroscope.” (Herve Lefevre)
Interferometry, a measurement process using electromagnetic and optical waves, is used to analyze the “angular frequency” and “velocity” of light, Lefevre’s essay explains. Simply put, the science of measurement movements enables computers to calculate a continued trajectory with specific location details. This complex scientific process, White explained, naturally bears heavily upon combat performance.
In addition to engineering technologies to leverage or optimize results emerging from these scientific phenomena, Northrop Grumman developers have built additional security measures into the EGI-M by separating off or stovepiping specific elements of the system which might be vulnerable to interference if left open or “pooled” within broader scope of functional areas.
“The real magic is we are isolating functions for core navigation, airworthiness, and cybersecurity from an open area that can be used to insert new apps, including from 3rd parties, for specific mission requirements,” White said.
Also, as opposed to mechanical gyroscopes which have been used in missile systems for several decades, Fiber-Optic Gyroscopes are inherently more secure, according to a 2000 essay from the International Society for Optics and Photonics called “Progress in the Development of Gyroscopes for Use in Tactical Weapon Systems.”
“A FOG provides extremely precise rotational rate information, in part because of its lack of cross-axis sensitivity to vibration, acceleration, and shock. Unlike the classic spinning-mass gyroscope or resonant/mechanical gyroscopes, the FOG has no moving parts and doesn’t rely on inertial resistance to movement,” the essay states. (Paul Ruffin)
Ruffin goes on to explain that the Pentagon’s development of Fiber Optic Gyroscopes have been fast increasing in recent years, building upon years of work applying Gyroscope technologies to weapons systems.
“During the past two decades, tremendous progress has been made in advancing the performance capability of solid-state optical gyroscopes for use in tactical weapon systems,” Ruffin writes.
White added that the EGI-M is engineered for the future, as it is already being migrated into additional systems. This is expedited through the use of carefully established technical standards intended to enable continued modernization and software upgrades over time.
Ultimately, the goal with EGI-M is to “position all the DoD platforms to integrate navigation software upgrades as quickly as the threat environment changes,” White said.
Kris Osborn is the defense editor for the National Interest. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.