Avionics enter the fifth generation

Advanced military aircraft such as the F-35 Joint Strike Fighter, the F-22 air-superiority jet fighter, and the E-2D Hawkeye carrier-based maritime patrol and radar surveillance aircraft will have powerful avionics systems like never seen before.

Oct 12th, 2008

Advanced military aircraft such as the F-35 Joint Strike Fighter, the F-22 air-superiority jet fighter, and the E-2D Hawkeye carrier-based maritime patrol and radar surveillance aircraft will have powerful avionics systems like never seen before.

By J.R. Wilson

In the evolving network-centric battle space, the need for all components to share information in real time, to see a common picture, to be able seamlessly to hand off targets and change missions, to be aware of the identity, location and movements of friendly (blue) and enemy (red) forces has become paramount.

The air-land-sea doctrine of the late 20th Century is becoming a truly unified joint force in the 21st, placing demanding new requirements on avionics -- not only for fifth-generation fighters such as the F-22 and F-35, but also for legacy aircraft and new-model upgrades. Among the latter, one of the most extensive avionics upgrades is on the U.S. Navy carrier-based E-2D Advanced Hawkeye airborne early warning and battle management aircraft.

"Avionics is always a challenge -- first to support what we've got, second to keep it current at least through 2020," says Capt. Randy Mahr, program manager for the Navy's E2/C2 Hawkeye. "We just finished our last approval process to take a single-board COTS computer and replace the existing computer. Assuming funding, we will start the transition to an open-architecture environment by separating the applications from the operating system -- transitioning from a legacy UNIX to a Linux system.

"I had to get to a commercial operating system to keep pace or I won't be able to guarantee compatibility in 20 years with the chips I have today," Mahr continues. "Keeping pace with commercial advances does bring some cost to DOD, because when I need to replace a component, if it is not being manufactured in an open environment I can put something new in, but will have to pay the safety and integration costs. We haven't reached a point of doing that yet to know how big that bill will be, but there is a cost to staying up with current technology, not even trying to get on the cutting edge."

While more than three decades newer in design, the F-22 -- the world's first fifth-generation (stealth, speed and integrated avionics) fighter -- which achieved initial operational capability (IOC) with the U.S. Air Force in December 2005, also is dealing with avionics upgrade issues.

"When the fighter was put in place, it had data links that are only capable of communicating within the aircraft," says Jim Byloff, director of F-22 Communications, Navigation and Identification (CNI) at the Radio Systems business of the Northrop Grumman Corp. Space Technology sector in San Diego. "More recently, leaning toward advanced waveforms and Internet protocols (IP) provides an ability to link the data into the net, using an IP addressing file to send data between aircraft and the ground and the aircraft.

"About three years ago, the Air Force required a TTNT (tactical targeting and networking technology) waveform, which is an advanced wideband data link, but they are considering other paths, such as MADL (multifunction advanced data link), which we use on the F-35," Byloff says. "The advantage of the new data links is they are more ad hoc in their networking, so it takes much less preplanning."

TTNT has been called Link 16 on steroids, although its capabilities are still considered inadequate to exploit the full potential of next-generation platforms.

"It's a unique waveform that has much more bandwidth than the current ones to pack more data onto the aircraft and more seamlessly share with other platforms and services," explains Eric R. Branyan, F-35 Mission Systems vice president at Lockheed Martin Aeronautics Company. "It's faster, but not superfast."

Even the F-35 Joint Strike Fighter (JSF), a decade newer in design and not scheduled for first deployment until 2013, is relying heavily on its integrated avionics open architecture to keep pace with rapid technology advances.

"It's a fifth-generation fighter and the latest and greatest technologies are in the airplane -- AESA (advanced electronically steered array) radars, electro-optic (E/O) capability to target the ground, off-board data links to transfer information from the F-35 via Link 16 and VMF (variable message format), etc. In the future, we're looking at a satcom (satellite communications) capability," says Lt. Col. Shawn Shanley, F-35 Air Systems Design Integration manager at the JSF Program Office. "In five or ten more years, there will be even better capabilities available."

F-35 Lightning II

As was the case with the F-22, the F-35 features integrated avionics architectures, with all individual sensors feeding into an integrated central processor and fused. The difference is another decade of technology evolution.

"Because the environment of network centric operations is fairly dynamic and still being defined in terms of the next advanced tactical data link and airborne networking -- whether it's IPv6 or something else in the future -- the F-35 will have a wideband networking rack in the post-SDD (System Development and Demonstration) timeframe," Shanley says. "We look to start working on that in Block 4 (about 2015) and implement in Block 5 (2017). That would be compatible with wherever DOD and our allies go in the future for network centric operations. That rack would be flexible, where we could put in individual cards -- not boxes -- with whatever those future data links are, whether TTNT or others being working on right now.

"We were told by the JROC (Joint Requirements Oversight Council) to design to the latest and greatest standards and the legacy aircraft would be moved to those standards, either through JTRS (Joint Tactical Radio System) or individual platform upgrades, so we can have interoperability," Shanley says. "Currently, we communicate with legacy and allied platforms primarily through Link 16, which is being built to the latest standard -- MIL-STD-6016C. As the JTRS program starts populating those legacy platforms with other capabilities, we will be compatible with whatever data link goes into the legacy JTRS box -- VMF, SatCom, TTNT, etc."

Such advances in communications are necessary to support the wide variety and significant volume of data the aircraft will be receiving and transmitting. While Link 16 is a cutting-edge upgrade for the current fleet, it does not have the capability to handle the coming demand.

"Fifty years form now, every platform will be plugged in and sharing data. The limitations in today's world are do you have enough bandwidth to push all that data around -- radar tracks, SAR maps, text messages, streaming video, etc. All take an incredible amount of bandwidth," Branyan notes.

"An F-35 will operate very well with legacy platforms over current links in terms of locating red and blue forces, as detected by current legacy sensors, such as on an Aegis cruiser or AWACS. Any kind of detections the F-35 gets is shared with the rest of the community so they have the same picture we have; there is latency using Link 16, which is a small pipe -- and a little latency in a fast-evolving battle can make the difference between winning and losing."

Those data also require major increases in computer processing power and memory to collect and fuse multiple sensor inputs into a single picture displayed to the pilot.

"Some legacy aircraft still have individual displays as part of their federated avionics and the pilots have to do the integration in their heads. Fusion provides the pilot with a more accurate picture," Shanley adds. "From a timeline standpoint, he can utilize incoming data right away and have a better picture of the environment.

"A lot of platforms, as they move forward, are moving more toward an integrated rather than federated picture. For the most part, though, you have to have the right architecture from the beginning. It's very expensive to put integrated avionics into a platform after the fact."

In many ways, the F-35's advanced avionics will enable it to act as an airborne server, collecting data from whatever sensors are available, onboard and off, fusing it into useful information and relaying the results -- in a compatible and accessible format -- to others. As a result, many legacy platforms will benefit from the F-35's advanced technology without requiring costly, if not impossible, upgrades of their own.

"The F-35 has data links between all F-35s, very wide bandwidth, high-speed, low latency, so if you have N-number of F-35s in range, they share information, which profoundly changes tactics and could allow other F-35s or legacy platforms to operate in a no-emissions mode, receiving the situational picture they need to engage from someone offset at an oblique angle. That includes low observable platforms (LOPs) and legacies," Branyan says.

"The legacies can be enabled with high-speed data link or through Link 16, but even low-speed network platforms can benefit from others with high-speed nets," he says. "You don't always need a SAR map on every legacy platform. We can just send the coordinates of the target rather than the whole map from the F-35 so they can still successfully engage those targets. So the F-35 doesn't leave the legacy platforms behind but provides them with data to engage, in some cases data they never had before because we can go into denied airspace, as a low observable platform, and provide information they could not otherwise get. And that can still be done by Link 16 or secure text or voice across other communications methodologies."

By pushing its integrated avionics architecture beyond the capabilities of other aircraft, the F-35 is the leading implementation of the preplanned product improvement concept, with the program office already contemplating future advances.

"One of the other capabilities we're looking at is streaming video, from the air to the ground or another platform. We use VMF mainly to do that and can still do the CAS (close air support) mission, but a lot of folks on the ground and other locations are interested in streaming video, so that is high on the list for Block 4 or, at the latest, Block 5. We're also looking at a link for network-enabled weapons," Shanley says. "Those are the big ones we're looking at -- wideband rack, streaming video, network-enabled weapons, SatCom."

Ken Fecteau, Northrop Grumman's F-35 CNI program director, says the keys to the future evolution of F-35 avionics are continuing evolutions in processing power -- including digital signal processors -- memory, miniaturized components and software-defined radios (SDRs).

"Advances in memory are just as important as advancements in processors. MUOS (Mobile User Objective System) is a very complicated waveform, for example, and some of the new high data rate waveforms are not only very sophisticated, but process very quickly. To send decent resolution streaming video requires a tremendous processing speed. So processors and memory are the key enablers," Fecteau says.

"We are in the interesting position now that commercial rather than military leads all technology development, which lowers the cost of defense programs and improves supportability and reliability, due to the larger market. And we don't have to worry about them going obsolete in quite the way that mil-spec did."

At the same time, however, the evolutionary capability of the F-35 during its anticipated 50 to 70 years of operational service could easily take it beyond the ability of legacy and allied platforms to adapt -- at least those now flying that will remain in the force for the next two or three decades.

"We don't just leap ahead because we can. We have to make sure we are compatible with the force structure and interoperability roadmaps the government is laying out. It doesn't do anybody any good if you have someone out there with a version that doesn't connect with anyone else," Branyan says, adding that can be difficult, even with the best of intentions. "The government acknowledges they have a challenge in that standards may be established by a group, but the capabilities are bought within the services and down within various communities, so they have a hard time synching on the standards and deployments in a coordinated fashion."

F-22 Raptor stealth fighter

As the world's first operational fifth-generation fighter, the F-22 marks the current state-of-the-art in the movement of military avionics from a federated system of individual boxes performing specific tasks to an integrated suite providing far more capability with significantly less impact on the aircraft and program.

"The CNI system is about one-third of the software on the aircraft, a substantial portion of the F-22," Byloff says. "Previous platforms used a black box or federated approach, with each radio a separate box, so it took much more of the physical volume and added a lot of weight. Advantages of the integrated system, in being software-defined radio and using shared resources, are much smaller volume, lower weight and lower cost while providing much more advanced capability.

"I've been seeing requirements for more and more functions, such as the ability to fly over different countries and regions with different ATC systems and more use of sensors. The F-22 is the first into the battlefield, so we want to quickly communicate back the state of the battle space. The big focus has really been on data links, with networking the key to working with UAVs and other aircraft. The ability to communicate with the ground force is another big push. All of that requires networking, so the data links are becoming more and more important."

For the network centric battle space now evolving, the network is only as valuable as its nodes (air, land, sea and space platforms), the nodes only as useful as their ability to access and communicate with others through the network.

"This network -- or, more appropriately, this network of networks -- must support a full spectrum of combat and non-combat operations while producing a coherent tactical picture that enables precision engagement against fixed, mobile and time sensitive targets," says Col. Robert Trosi, chief of airborne networking at the Air Force's Air Combat Command. "In the future, the warfighter needs a distributed system of systems, composed of tactical data links (TDLs), IP-enabled networks, common interoperable software and seamless gateways, all supported by a robust requirements definition and information assurance process.

"Because early capabilities were developed independently by multiple, uncoordinated, platform-centric initiatives, critical gaps in the infrastructure continue to exist. We must bridge these gaps, increase interoperability and build connectivity into future systems up-front to ensure that we can leverage the unique capabilities of both our new and legacy systems."

With new aircraft programs at a minimum for the foreseeable future and legacy platforms expected to remain in service for decades beyond their original planned life spans, finding ways to enhance legacy avionics becomes a high priority. Given the speed of technology evolution, even the F-22 falls into a "legacy" environment barely two years into deployment. And while some waveforms can be incorporated directly into the current F-22 system, Byloff acknowledges the Raptor is not a truly open architecture design.

"But the refresh already underway will provide a JTRS-complaint type architecture that allows it to be upgraded purely through software changes. The key to that is the SDR capability that allows you to lay in a new waveform in an almost plug-and-play approach. So it isn't fully open today, but will be in the future -- 10 years down, the F-22 definitely will have an open architecture," Byloff says.

"It has a capability sufficient to do its current mission, but they are adding new mission capability every day based on the roadmap being developed by the Air Force. As we add new capabilities, we do it in a way that refreshes the architecture to make it easier to add even more new capability in the future."

As the Raptor increases its presence in the Air Force fleet, it also is demonstrating the new paradigm a fifth-generation fighter brings to the tactics and operations of the entire air component.

"When the F-22 conducts exercises, data are transmitted seamlessly between them and F-16s and they found they began using them a lot like mini-AWACS," says Branyan, who previously headed Lockheed Martin's F-22 mission systems team. "Their radar detection ranges and ability to detect when in a non-emitting mode, then send that data to other friendly forces, gives them a huge edge on the ability to engage," Byloff says. "That F-22s engage at a factor of 80-to-1 in terms of loss ratios is a testament to that platform, but also an enabler for legacy platforms, so F-15s, F-16s, F-18s get the same god's-eye view and can be vectored to engage without turning on their emitters and so get picked up on enemy sensors.

"There is a synergy between fifth-generation low observable platforms and the advanced fourth generation and the glue that holds them together is the ability to be interoperate and send the battle picture back and forth," Byloff continues. "Nobody gets left behind; they just get used in ways we had not envisioned before. As more LOP are deployed, they will make the legacy aircraft even more capable because, by flying high and moving about the battle space quickly at supercruise, they can get a bigger perspective of the overall airspace and data link that to other platforms and command centers so adversaries can be engaged on multiple fronts. LOPs get the first look to allow everyone else to get a first shot. And that is a big game changer."

E-2D Advanced Hawkeye

While the outward appearance of the Hawkeye is little changed from its first iteration in the 1960s, the E-2D is a strikingly different aircraft internally, where integrated multifunctional systems are replacing federated single-purpose boxes. From a glass cockpit to a two-generation jump in radar to the addition of a semi-virtual crewmember, the Advanced Hawkeye is being positioned for carrier fleet deployment in 2013 as fully compatible as possible with the technologies going aboard the F-22, F-35 and other 21st Century aircraft it will be supporting.

With its adaptive processing, the new radar can see into ground clutter, enabling the E-2D to add new overland capabilities not previously part of the Hawkeye mission. Adding support to land and littoral forces will require greater capacity to manage information for all U.S. and coalition services. Handling that level of inter-service message traffic is one of the biggest problems the program office faces.

"Part of it is how do we work in acquisitions to keep ourselves informed. We can't live in a stovepipe. We talk to our peers to keep aware of what everyone else is doing so we can deliver a capability, not just a hunk of metal, so we can get that net-centric battlefield up and running. It's a challenge," Mahr notes -- a challenge that other new players will only expand.

"We understand UAVs are coming. There are limited numbers out there at the tactical level and at the larger theater level, but right now none of those are tied to us," Mahr continues. "We're looking at ways to do that, how to take their sensor data to expand over the horizon, put that on my server and let somebody on the ground or on a ship take it off my server and I don't even have to be involved in the transfer, it's machine-to-machine. That's one of the demonstrations we've done on how we will work with UAVs in the near future; 20 years form now, it may be different."

The E-2D represents a complete next generation upgrade of the mission system. "We started with the radar, then expanded it to the entire weapons system, new integrated navigation and safety systems and a glass cockpit with three multifunctional displays (MFDs), completely selectable and interchangeable. We're upgrading radios so JTRS will plug in," Mahr explains. "The advances in avionics allow us to incorporate high-speed data on a broader fiber optic backbone -- rather than just depending on 1553 -- to get real-time capability. The back end will look a lot like the current system, but we will upgrade those to lightweight displays, perhaps flat panels and touch screens as those technologies mature for the military environment in the next few years.

"All E-2s are the same size, so we can't fit anyone else in the back, but we are processing a lot more information," he says. "In the E-2C today, we have two pilots up front, three operators in back. Pilots have access to the radios, but none to real-time mission data other than what they get from crew in back. In E-2D, we're taking advantage of the MFDs up front to include mission data, which the pilots can call up. Essentially, one pilot flies the airplane and the non-flying pilot can operate as a weapons system operator -- a Tactical Fourth Operator."

The production line at prime contractor Northrop Grumman has been revamped to deal with what is essentially a complete redesign. As a result, however, "it would not be cost-effective to retrofit even part of the E-2D suite" onto earlier models, even the latest E-2C Hawkeye 2000," says the Navy's E-2D chief engineer, Tom Maratta.

"The open architecture of the E-2D will enable future technology refresh and insertion as it continues to fly into mid-century," he says. "The big thing we're looking at is, as electronics get more dense in the aircraft, we can pursue other capabilities -- advances in networking, automated decision aides so we can better use the people in the airplanes, letting the computers make the easy decisions so the humans can handle the higher level stuff. Some of those future evolutions, he says, will be coming from advances in commercial and unmanned systems. "The gaming industry is driving huge investments to get denser and denser processing capability. They are approaching supercomputers-on-a-board, even a chip that we can leverage for radars, which require huge amounts of processing.

"It is spawning a lot of ideas on advanced networking ideas -- the GIG (Global Information Grid) across the entire chain from the single soldier to the UAV to larger forces," Maratta says. "There have been airborne server concepts that came out of the UAV world, where they were looking at how to capture and archive all that data and make it available in a publish-subscribe environment for those who need it. We can now more tightly couple those chains."

The E-2D is about 1500 pounds heavier than the E-2C, primarily due to the move to a modern, all-digital radar with upgraded processors, high-voltage power supplies, power amplifier modules, etc. As with the F-35 and F-22, however, the overall avionics suite has decreased in weight even as capability has significantly increased.

"The key for the Hawkeye, as a platform flying into the middle of the century, will be improved radios -- the generation-after-next -- and how to tie the radios directly into the servers. I'm a flying antenna farm -- how do I get that down so I don't interfere with myself and get larger amounts of data out? It's about moving the information to a soldier with a handheld VHF, via satellite over-the-horizon to national resources, whether a ship or theater headquarters, by UHF to allies. Communications will be the next leap," Mahr says.

"Beyond that, the question is what's the next airframe. I don't know if there will be an E-2E. I'd like to get rid of the rotating antenna on top and put flat panel radars and AESA type radars on the aircraft, improving reliability and reducing drag. Then tie that into UAVs, both information exchange and control. If I can get UAVs working together to get essentially a very large aperture radar and keep it up a long time, the smaller the things you can see. As a naval aviator, I firmly believe there will always be a place for human-in-the-loop for decision making, but not all the information has to come from the airplane that person is sitting in."

As improved avionics fuel the growing interaction of various manned and unmanned air, ground and naval platforms, he adds, command and control becomes much more important than the Hawkeye's half-century-old early warning mission.

Much of that new capability is coming from non-aviation commercial developments -- a source that is certain to grow as military avionics become more software than hardware, although routers and servers developed primarily for commercial networks also are and will continue to play a role.

"Part of the E-2 story is it is not just about what is in the aircraft anymore, but using avionics to get information out of the aircraft to people who need it; not just open end software, but also hardware, such as integrating radios quickly," Mahr says. "We're looking at how to use commercial-type search engines to find information in large databases. Along with that is how we handle data from an information assurance perspective and what we can learn from the IT and banking industries to make sure data packets are complete, trustworthy, not corrupted in transmission and, if I hand it off to someone else, they still know it came from you.

"We're already employing some of these techniques, but can no longer depend on a WSG84 (Defense Mapping Agency World Geodetic System of 1984) grid coordination system to provide accuracy. The soldiers on the ground today need more current information, including where it came from, what has changed," Mahr continues. "And for all that we are leveraging commercial technology growth. Technology isn't stable, so we have to provision today for what they will want to put in the airplane in the 2030s. Right now I have 200-plus suppliers coming through Northrop Grumman, my prime, and I expect someday to have 2000 suppliers, most coming directly to me, so I can put their applications on and configure the airplane as necessary."

Just as today's pilots come from a generation accustomed to high-fidelity computer-generated graphics -- which led to major changes in training simulators -- the next generation is developing skills on home game boxes, multi-function cell phones, and advanced computers that will impact future avionics interfaces.

"Right now most of our weapon systems interfaces are trackballs. When we created the Tactical Fourth Operator, we spent a lot of time on how that operator should deal with the information and display. If you look at the ability to put a glove on my hand and move things around on a display without ever touching the screen, I can start getting rid of trackballs, which reduces weight, improves reliability," Mahr says. "We're not there today, but will be shortly; as safety and reliability improve, I'm certain they will be on military aircraft within a decade, matching what the crews of the future are growing up with today."

Overall trends

Pushing the avionics envelope is easier for new platforms or even significantly revamped new models of legacy aircraft, but every effort is being made to bring as much new capability as is physically and budgetarily feasible to every platform -- U.S. and allied -- that will be operating through the next few decades.

"Our primary upgrade current requirements are to equip aircraft with radios and data links that allow dissimilar aircraft to collaborate in the net-centric environment. That gives us flexibility in our missions and execution, which is a key, along with timeliness," notes Brian Hicks, chief architect at the Air Force Aeronautical Systems Command. "Weapons also are being networked now and equipped with data links, so we can have a weapon enter the network as well."

For aircraft that stick with Link 16, the government is looking at the use of gateways.

"The big advantage of the gateway is being able to translate into all the waveforms out there so all the aircraft can communicate, making it a nice force multiplier," Byloff explains. "BACN (Battlefield Airborne Communications Node), for example, is an Air Force program to put a gateway in the sky that will take in different waveforms and connect to other waveforms on other aircraft. It could take data from the F-22 and convert it to Link 16 to go out to other aircraft, so they don't have to have the same waveform as the F-22. That is one way to deal with compatibility where they can't retrofit; where they can, they will use either JTRS components or other SDRs."

Some of the enabling technologies to achieve a truly net-centric, interoperable battle space include low probability of detection/low probability of intercept radios and waveforms, multiple levels of security for information assurance, data guards to allow information to cross security domains, better sensor fusion so E/O, radar and IFF data can be used to create a more coherent picture, being able to track massive amounts of information without overloading displays and filtering out information that is not relevant at any given time.

"A lot of our legacy aircraft will be around quite awhile, so most of the upgrades we are doing to them involve radios and modems -- some still don't have Link 16, for example. We're looking at encryption, new displays, buses, processors and the software to be able to process everything," Hicks adds. "There has been some desire to have the ability to change software rapidly and we are examining ways to do rapid software insertion.

"Our C2 infrastructure also has to be flexible, so if I add a waveform, radio or data link to certain nodes, unless they only want to talk to themselves, the C2 infrastructure has to change, as well. Most of our legacy systems now support the situational awareness and collaboration of red/blue force tracking. We are upgrading them to be able to talk to the ground, to get Link 16, to get the integrated broadcast intelligence service, etc.

All of these advances in avionics are giving the U.S. military yet another significant leap in capability over any prospective enemy -- but also create potential new problems for allies and coalition partners.

"As technology advances, how do we keep that refresh rate going and enable our partners to put onto the aircraft they have the capabilities they need to support their national needs?" Mahr asks. "It is a growth in network capacity to wider and wider nets.

"But our international partners are not upgrading at the same rate we are, so one of my goals is to supply information at their level of need. So how do I take this huge amount of information I have, extract what is needed, put it into a compatible transmission medium and meet what the user needs, whether I'm talking to an advanced U.S. user or an ally with legacy platforms that may not have the wide pipes?"

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