Beyond GPS: U.S. Navy's plan for assured position, navigation, timing

Barry Rosenberg, C4ISRNET.com,
8 September 2015

CAPT Mark Glover is the program manager for the Navy's Communications and GPS Navigation Program Office (PMW/A-170), part of the Program Executive Office for Command, Control, Communications, Computers, Communications and Intelligence (PEO C4I) at the Space and Naval Warfare Systems Command (SPAWAR) in San Diego, California. Glover was previously the commanding officer of SPAWAR Systems Center Atlantic in North Charleston, South Carolina.
PMW/A-170 is the Navy's lead for position, navigation and timing (PNT), and Glover spoke to C4ISR & Networks Editor Barry Rosenberg about assured PNT and operations in GPS-degraded environments.
Top of mind for many people is how to conduct PNT in degraded GPS environments. Tell me about the work of PMW-170 in this area.
CAPT MARK GLOVER: From a GPS perspective, one of the key things we are focused on is GPS modernization. There is an increasing threat out there for GPS, and our enemies know that. We are working very hard to ensure that we deliver our GPS capabilities to our fleet faster. There are a lot of modernization efforts that are going on across the Navy today; we are working in 170
along with our stakeholders across the naval enterprise and our stakeholders at the Global Positioning Systems Directorate at Los Angeles Air Force Base [part of Air Force Space Command] to ensure that we deliver these new modernized capabilities to the fleet.
What are the greatest threats to GPS-enabled PNT today?
GLOVER: As you know, GPS is ubiquitous. There is an increasing reliance on GPS across all ranges of military operations, and, of course, we can't forget our critical civilian infrastructure as well. Additionally, GPS jammers have proliferated around the globe, from large and complex militarized jammers to cheap and inexpensive units you can buy online. That means that not only that our peer and near-peer potential adversaries are capable of impacting GPS, but we must be mindful of non-state actors, as well.
Furthermore, we are trying to predict other methods that might be employed against our systems, such as cyber threats. Because it is not just a threat against the radio frequency signal, it is a threat against the actual systems that control those. Over the past 20 years, GPS has been a force multiplier for our military. But we cannot assume that any longer. We have to be proactive in protecting this valuable resource.
What are the specific challenges associated with PNT in a GPS-degraded environment?
GLOVER: Let me put a little context on top of it. The GPS satellite signal at a user's antenna is very low power. To put that in perspective, a 100-watt bulb is [10 to the 18th power] more powerful than a GPS satellite signal at the receiver's antenna. A low-power jammer can disrupt GPS operations.
To that end, denial and degradation of GPS can have myriad effects on our systems. Without protection, our ships, submarines and aircraft won't be able to properly navigate. Some of our sensors might not function properly, and provide erroneous information to our war fighters. Plus, time and frequency is a critical part of our communications infrastructure. Disruption of time can prevent those networks and communications systems from functioning properly, as well. Our weapons — interacting autonomously or semiautonomously — can be attacked. I could probably go on, but I will just say that GPS is fundamental to everything we do. It is a part of our plumbing today.
What are some of the alternative means of navigation you are developing, which you would rely upon in a degraded environment?
GLOVER: Some of the things we are looking at today include celestial navigation as a potential source, magnetometry and other signals of opportunity. In some of our newer systems, we tightly couple GPS navigation systems with inertial navigation systems. They have a symbiotic relationship where GPS can calibrate the inertial system. Correspondingly, the inertial system can compute positions during a GPS outage. They work in a dual fashion.
We can use precise clocks. That is another way to help maintain position and time during an outage of GPS [so] if we lose our GPS signal we can maintain the time we need for our networks. It is key that we continue to have the precise time that we need for our networks, combat systems and weapons in a degraded environment.
We are also working to use the next generation of GPS called M-code. M-code is a new DoD effort to modernize the GPS. It provides an additional level of protection for our GPS signal [through the combined use of high-gain directional antennas and wide-angle antennas to broadcast the M-code from next-generation GPS III satellites]. I have a team that is co-located in Los Angeles at the GPS Directorate, and they work on modernization issues such as M-code, as well as day-to-day efforts that we have with GPS across the naval enterprise. That is a new effort that we are going to pull out in the next few years across DoD.
You recently issued a request for information on assured PNT. What you are looking to discover with that?
GLOVER: We are trying to engage industry to assess different alternatives for network-centric assured PNT capabilities for our fleet. Recently, we had about 25 companies in for an assured PNT industry day to learn about how we can leverage the many innovative technologies that are out there. We are not necessarily looking to develop anything from scratch. We are looking for promising technologies that we can deliver to the war fighter soon. We want industry to leverage open architecture developments like GPS-Based Positioning, Navigation and Timing Service, which is called GPNTS. That is another program under my purview here at PMW/A-170. The bottom line is that the taxpayers have made a lot of investments in programs like GPNTS. We need to make sure we eke out every bit of capability in a system like GPNTS to enhance PNT for the war fighter. We want industry to help us develop anti-jam antenna technology that could be used on smaller platforms in a maritime environment such as UAVs and other small platforms.
What is the time frame for the next steps and possible RFPs?
GLOVER: We are continually looking at ways to do rapid innovation. With GPNTS, we should be fielding that within the next few years. As we field GPNTS we will continue to do rapid-innovation-type efforts and engineering upgrades to the system so we can improve the system and provide more. This will be a continually evolving effort as we go forward.
You are also working with Naval Air Systems Command on anti-jam capabilities? Tell me about those efforts.
GLOVER: As you probably noticed in the name of the program office, it is PMW/A-170. Not only am I PMW, but I am also PMA [Program Management Activity]. We work with Navair to integrate GPS-based solutions on different aircraft across the naval aviation enterprise.
One of the major efforts we have going on today is integrating an anti-jam antenna on our F/A-18E/F/G models at Navair. We also have integrated solutions on platforms such as an MV-22 Osprey, CH-53E, AV-8B and other platforms. We also provide subject matter expertise to
the Navair platform program offices. One area of particular note: that our team is working on smaller form-factor, anti-jam antennas that can be used on size-constrained platforms, especially UAVs.