Software Reprogrammable Payload (SRP): NRL's Airborne Box Brings Connectivity, Jamming to Troops in Remote Areas

It started as way to patch together radio communications for users on-the-move; but now Software Reprogrammable Payload (SRP) is also a way for troops and Command to share images and other data, even across remote areas, and engage in electronic warfare. Chris Huffine of the U.S. Naval Research Laboratory (NRL) leads SRP development and testing, and NRL plans to transition 100 SRPs to U.S. Marine Corps (USMC) Aviation starting in 2016.

ChrisChris Huffine leads the development and testing of Software Reprogrammable Payload (SRP) at the U.S. Naval Research Laboratory (NRL). We're not trying to replace the standard military green radio that industry already builds, says Huffine. We're trying to provide that server or that nexus that allows you to tie all those different radios together.
(Photo: U.S. Naval Research Laboratory/Jamie Hartman)

SRP becomes a center hub—allowing voice communications, data communications—between aircraft, between ground forces, between possibly users on ships, Huffine says. It's a key part of what the Marine Corps calls digital interoperability.

SRP has evolved to include signals intelligence (SIGINT) and other capabilities in the radio frequency domain, such as jamming and other kinds of electronic attack. The next generation of SRPs, called Spiral 2, is planned to include Tactical Targeting Network Technology and Link-16. Using the same hardware, just bringing up a different application, says Mark Haffner, who also works on SRP.

Says Huffine, You can talk to the aircraft, you can talk to the guys in the squad on the next hill [even when] there's a mountain in between you, you can talk to your commander back at a forward operating base and say, 'Permission to do this?' You can talk to the intel guys, you can say, 'Hey, we hear suspicious chatter going on.'

USMC is going modular: from cargo ships that will swap in flight decks, to body armor with removable parts, to cell phones that Brigadier General Frank Kelley (Vice Commander, Naval Air Systems Command) has likened to building phones with Legos.

SRP, with independent software applications much like a smart phone, is part of this reimagining. Processors and memory get faster every year, and you can plan to upgrade parts of your system and program it into the budget cycle, says Huffine. And then you'd be able to port over your old apps onto the new hardware. Compared to the old way, reinstalling entirely new systems with all new software, We can save a lot of time and money getting the capability to the field.

Says Haffner, We could add new capabilities to SRP based on their new capabilities in the field. By being modular, SRP will evolve as the military increases its capability to control the electromagnetic spectrum and looks to include new devices, like smart phones and tablets.

The Marine Corps has already made SRP an assumed capability in their Marine Air-Ground Task Force (MAGTF) Electronic Warfare [PDF] concept. It's adding new capability they didn't even have before, mainly because the size, weight, and power of putting all these capabilities individually on a platform would exceed [the aircraft's payload] capability, says Huffine, or compete with people and other gear for space.

The Office of Naval Research (ONR) and the National Security Agency (NSA) also contribute to SRP's development.

SRP allows reach-back from the pointy end of the spear to Command

CablesMark Haffner of the U.S. Naval Research Laboratory (NRL) connects a cable to Software Reprogrammable Payload (SRP). SRP has evolved to include signals intelligence (SIGINT) and jamming and other kinds of electronic attack: Using the same hardware, just bringing up a different application, says Haffner.
(Photo: U.S. Naval Research Laboratory/Jamie Hartman)

We're not trying to replace the standard military green radio that industry already builds, says Huffine. We're trying to provide that server or that nexus that allows you to tie all those different radios together. Be it units separated by mountainous terrain, different services and allies, or troops operating in an environment with crowded frequency assignments or jamming, SRP makes the connections.

A single hop allowing a squad to be able to talk over the mountain to the next squad or back to headquarters is one thing, says Huffine. But as the military continues to operate in remote areas without the traditional, large contingents of support, they need to be able to reach back to Command or the Pentagon when satellite communications (SATCOM) isn't an option. When you're out at the pointy end of the stick, you're kind of disconnected from the world.

Today, They don't all have the reach-back capability until they get to a Humvee or some larger vehicle that may have a SATCOM capability or an HF [high-frequency] capability or something that provides a beyond line of sight capability. If SRP were installed in platforms already deployed around the world, the military would have reach-back from anywhere.

Says Huffine, The digital interoperability idea is to get as many Marine Corps aircraft capable of being those nodes in that 'string of pearls,' as they sometimes call them—in addition to Navy, Air Force, whatever types of aircraft are available. So maybe you have a KC-130 tanker that's up there, you know, keeping those MV-22s filled up with gas: it might be a key node in the string of pearls.

Brian Adamson in NRL's Networks and Communication Branch is helping teach SRP to automatically discover such nodes. As more and more battle space technologies, like SRP, become digitally interoperable, NRL must continue to manage these increasingly complicated networks.

Layers of software running on top of Linux mean extra security and expertise

SRPA Software Reprogrammable Payload (SRP) sits in the testing bay at the U.S. Naval Research Laboratory (NRL). That idea of get as much information as you can, understand the problems as well as you can, really comes from that heritage of building space systems over the years, says Chris Huffine, who leads the project. SRP connects communications between commanders, aircraft, troops on the ground, and others.
(Photo: U.S. Naval Research Laboratory/Jamie Hartman)

What ties it all together is a software development architecture that allows you to make these applications and make them work together, says Huffine. Just like Apple doesn't create all the applications for that phone, we can give out that software development kit and we can engage academia, FFRDCs [federally funded research and development centers], and industry to help us.

SRP uses an NSA software architecture called REDHAWK, and NRL now serves as a REDHAWK Center of Excellence. It also opens us up to a whole new world of applications and application developers from the intelligence community, says Huffine.

What we wrote runs on top of Linux, says Haffner.

Adds Huffine, It means we're saving lots of money on licensing fees. There's many layers of software, and we utilize open-source or government-owned software as much as we possibly can and write as little as we possibly can.

When the development of Spiral 2 SRPs is complete, Naval Air Systems Command (NAVAIR) will oversee their transition to industry for manufacture.

The major change between Spiral 1 and 2 SRPs is the additional comprehensive layers of security, which Swati Shah in NRL's Center for High Assurance Computer Systems has been developing over the last two years with NSA. That means we have cryptographic capability to protect the data that's being transmitted over the RF links, it means we have encryption to protect the software that's loaded on board the SRP, and there's a whole architecture that's designed to protect the box against intrusion or any sort of malware or things like that, says Huffine.

NRL shares Congress' and the Department of Defense's (DoD's) concerns about vulnerabilities in the defense electronics supply chain [PDF]. There are trusted part suppliers and there's other methods we can use, says Huffine. There is no single answer, but we build security mechanisms that are essentially layers of security on top of security.

Actually, it is rocket science: high testing standards make for excellence

One of my biggest lessons learned in the 15 years that I've been doing this is you can never collect enough data, says Huffine, because if things go wrong you want to understand why. You can't just ask a KC-130 tanker aircraft, 'Hey, umm, yeah, the box just crashed, can you reboot it?'

MV-22 An MV-22B Osprey is refueled by a KC-130 en route to Hawaii in July 2014. If the U.S. Naval Research Laboratory (NRL)-developed Software Reprogrammable Payload (SRP) were installed on KC-130s and other platforms already deployed around the world, the military would have reach-back capability from anywhere. When you're out at the pointy end of the stick, you're kind of disconnected from the world, says Chris Huffine, the NRL project lead.
(Photo: USMC/Lance Cpl. Evan R. White)

NRL builds SRP and other communication technologies out of a department primarily known for space systems. Spacecraft are the ultimate thing that you don't want to crash, says Huffine. So that idea of get as much information as you can, understand the problems as well as you can, really comes from that heritage of building space systems over the years.

Before flying SRP on an aircraft during a major military exercise, NRL rents a prop plane from a small airport Maryland. It's our private, work-out-all-the-kinks event, says Huffine. He adds, Renting an aircraft allows flexibility for testing. They don't flinch quite as much when you ask for an antenna installed on the airplane.

While SRP is in the air, We do real time status displays of the telemetry coming down, so we know right away what's going on, says Haffner, at a level of detail far exceeding what a regular user in the field would ever need.

A few hours after landing the aircraft we have a really good idea of how well we did, says Huffine, so if we want to make any changes or tweaks we have that information available before the next flight, which might be in a few hours.

Rigorous testing up front pays dividends, in Huffine's words, with successful exercises. Our first big SRP demonstration was at [Marine Corps Air Base] Yuma at WTI [Weapons and Tactics Instructor course trials]—that was in 2012, he says, when SRP was installed on a KC-130. We were linking up Yuma with Twentynine Palms, which are 150 miles apart or so; we were collecting SIGINT from 200 miles away, in the Pacific Ocean; we were doing SINCGARS [communications] relay. We got to do the full Monty, everything was working.

SRP has also been demonstrated on USMC MV-22 Ospreys (tiltrotar aircraft), unmanned aerial vehicles (UAVs), and Humvees. Most recently, Huffine says NRL demonstrated how SRP could provide an alternative if the SATCOM link was denied or went down during ONR's Agile Bloodhound exercise.

NRL brought SRP to an NSA exercise in August, called Storm Force, and plans to continue participating in WTIs through the Marine Corps Warfighting Laboratory and ONR.

Technology's answer leaves doctrine questions

SRPSoftware Reprogramable Payload (SRP), developed at the U.S. Naval Research Laboratory (NRL), would increase USMC's digital interoperability. SRP becomes a center hub-allowing voice communications, data communications-between aircraft, between ground forces, between possibly users on ships, says NRL engineer Chris Huffine.
(Photo: U.S. Naval Research Laboratory/Jamie Hartman)

One issue SRP brings forward is combining so many capabilities that are regulated under different governmental title authorities—electromagnetic spectrum operations, electronic warfare, and cyber operations—in one box. SRP allows you to hear that the bad guy is talking about setting off an IED, and then press the button to jam that communications so he can't finish his message. Under current law, however, listening and jamming are regulated by different titles in the U.S. Code and fall under the purview of different federal agencies.

Additionally, quick communications between the Command Center and the Marine on the ground could collapse traditional command and control and information sharing processes.

SRP gives a technical solution for bringing many capabilities together, but where SRP will go in the future will continue to be a partnership between the Naval Lab and Naval leadership.