Advanced Terminals Near Delivery

The Air Force’s family of advanced beyond line-of-sight terminals
(FAB-T) program is moving toward a key milestone.

By Adam Baddeley
 

The Air Force’s family of advanced beyond line-of-sight terminals (FAB-T) program, which is designed to exploit the new highly secure, survivable communications capabilities offered by the advanced extremely high frequency (AEHF) satellite constellation, is moving toward a key milestone, with initial delivery by the end of the year.

The goal of the program is to ensure that strategic voice and data gets through to warfighters, whatever the circumstances. Initially, it will link key nuclear strike assets such as the B-2 and command and control assets in the air and on the ground. Subsequently, FAB-T‘s growth path will see the terminal fitted to ISR platforms such as Global Hawk, and in the future to the F-22 and F-35 for a greater tactical role.

“The nuclear mission is the key requirement for Increment 1 of FAB-T, but as we go into future increments we will not be looking at survivability aspects as much as our airborne intelligence, surveillance and reconnaissance requirements,” explained Air Force Colonel Chuck Cynamon, program manager for FAB-T, which will equip both manned and unmanned platforms and use the new AEHF constellation.

“The bottom line is that FAB-T is a network-centric family of terminals. What the Air Force did previously was that each platform went out and acquired its own radio. This was a stovepiped capability and incurred additional costs. With FAB-T, the terminal or B-kit will be supplied by the FAB-T program office, which will simplify logistics and future upgrades.”

FAB-T is an evolutionary rather than a single step acquisition, with two currently funded and two further increments planned. Increment 1 will provide protected survivable EHF communications to B-2, B-52, RC-135, E-6B and E-4B aircraft, with 197 terminals being acquired. Increment 2 will expand on this, bringing in additional capabilities such as a two-way Ku/Ka band SATCOM capability and 274 Mbps transponded Ka band communications across a further 41 terminals. It will also extend FAB-T to high altitude endurance (HAE) platforms such as the RQ-4 Global Hawk UAV.

Increments 3 and 4 are still largely unfunded, although science and technology (S&T) work on both has begun to address capability extensions, including the Transformational Communications Satellite (TSAT).

All hardware for the program is currently undergoing environmental qualifications, with the first terminal on schedule to be delivered to the B-2 program in December 2008. Boeing is leading the FAB-T work, along with several partners. L-3 is responsible for the programmable modem and terminal migration, and Rockwell Collins is undertaking development of the AEHF waveforms, data set management, the operator interface group (OIG) and specific RF components. ViaSat is responsible for programmable information assurance.

“Right now we are staying focused on December 2008 on all platforms,” said Jim Dodd, program director for FAB-T at Boeing C3 Networks. “The software is in integration and test and we are in the middle of hardware qualification. Now we are starting to pull the entire EDM terminal together between the operator equipment, the antenna group and the modem processor group with the software.

“We have already integrated and are going over the air with legacy Milstar satellites. We are launching into our next block on Increment 1, which is Block 8, focused on the XDR implementation and the command post functionality that will be fielded in March 2011. This builds on the current Block 6, which is focused on the airborne wideband terminal,” Dodd added.

Assured Communications

FAB-T is an evolutionary acquisition, Cynamon explained, that has been undertaken in a spiral fashion. “We don’t quite know what the end result for the final program increment is going to look like, although we have a good idea of what that will be, because users are still getting comfortable with new capabilities.”

As an example, Cynamon cited the launch of the first Wideband Global Satcom satellite, offering military Ka for the first time. “We expect that as users begin to use this capability, new requirements for Ka on FAB-T will come into focus.”

AEHF is the core of FAB-T capability, providing assured communications for nuclear missions. Increment 1 and 2 will operate using both the EHF LDR, ensuring backwards compatibility with the strategic capability on board today’s Milstar constellation, and offer the AEHF XDR when the constellation is launched. Future capabilities are also being eyed. “If Increment 3 comes along it will bring EHF XDR+, which will go up to about 45 Mbps to support TSAT,” said Cynamon.

In terms of ISR, beginning with Increment 2 the program will add Ka and Ku band communications, while FAB-T will also be able to communicate via the terrestrial Common Data Link. In contrast to Increment 1, a multi-channel capability will be provided via the advanced multi-band communications antenna system, which provides a small multi-beam, multi-band phased array antenna that enables simultaneous connectivity to more than one satellite.

Cynamon explained that the FAB-T program had adopted a paradigm of continual development in which at any given time the S&T, technology development, system development and systems production for successive phases are occurring simultaneously on a staggered basis.

“Increment 1 is now in systems development and will go into systems production starting in 2010. Right now we are doing technology development work on Increment 2 and are in the midst of developing a Ka waveform, some antenna work under AMCAS, and new multi-band radome for Ka on Global Hawk. This is as well as maintaining Ku capability and a 480 W high-power Ka band traveling wave tube for Global Hawk to support throughputs of 275 Mbps of data. In the next year and a half we will move into systems development on Increment 2,” he said.

“In the meantime, we are also going to fund Increment 3 technology development,” Cynamon continued. “We are currently engaged in a program with the Army and Navy called POET [programmable objective encryption technology] to provide gigabyte encryption. The programmable infosec module that we are developing as part of Increment 1 is compliant with the Department of Defense crypto-modernization mandate.”

Increment 4 is still in the early planning stages at this point.

“Extensibility is one key aspect of FAB-T. As we go through this we are not just designing for today, but are constantly looking at our requirements to make sure that the programmable modem is upgradeable to take the future waveforms,” Cynamon noted. “Although it is not implemented in Increment 1, networking capability is envisioned and required in future increments.”

Software Portability

By embracing future waveforms, levels of commonality have been adopted both in software and hardware to ensure that the architecture remains relevant throughout its service life. For software that has meant making FAB-T software defined radio and adopting the Joint Tactical Radio System’s Software Communications Architecture (SCA).

“The LDR and XDR waveforms are SCA compliant, affording the government a level a software portability that was previously non-existent,” explained Bob Geers, FAB-T program manager for Rockwell Collins Government Systems. “We are writing SCA-compliant waveforms from the ground up, not just modifying old software that is in use in legacy equipment.

“The government has already seen the benefit of this approach, as the FAB-T AEHF waveforms are being reused on the Air Force GEMS program development. That is another AEHF-protected SATCOM program that is part of the MEECN [Minimum Essential Emergency Communications Network].”

GEMS is the Ground Element MEECN System program, which will replace Air Force and Navy fixed and deployable communications for bomber, tanker, reconnaissance and other alert communications facilities.

“The SCA has been a help for us because its gives us the framework to help guide the development and separate hardware and software. The software on the program has been very stable. The problems that we have had have been in hardware,” said Cynamon. “That is primarily because of the platforms we are working with. The B-2 bomber has some very stringent survivability requirements on hardened terminals, and the B-52 has remarkable vibration when taking off and landing and when bomb-bay doors are open. But we still need to have full communications. These sorts of things have driven us crazy.”

These hardware issues were addressed in FAB-T’s 2005 restructuring, which pushed back the program’s schedule. “We re-baselined the hardware design and requirement as part of the restructure and we have had good results since then,” said Dodd. “When you look at the cost and schedule issues we have had in the last two years, it has pretty much been all hardware. The software team has done an excellent job and we have got very positive comments from Space Command in terms of the software package architecture and the way we have laid out the whole implementation. Also the actual results have been better than many of the programs that they have seen in the past. Software has been a big highlight of the program.”

At the core of the FAB-T design are two modem processor group boxes built to the Quad-X form factor to satisfy B-2 size requirements, but also slated to be rolled out to every Increment 1 platform. “All the other platforms, ground users and airborne users are happy with that configuration—everyone gets those two boxes. We are probably over-engineering the platforms for the needs of any one aircraft so it meets all platforms’ needs,” said Cynamon.

A similar level of commonality is seen in the OIG, which will use identical operator panels and data set manager equipment although there will be some differences elsewhere in the equipment suite. Significant differences appear in the antenna RF group with a ground fixed antenna and transportable antenna sharing a common dish and feed. The aircraft have different approaches, such as the large aircraft antenna that equips the B-52 and RC-135 fleets.

Rockwell Collins is responsible for the OIG—the display interface, keyboard, printer, operator panels that control the running of the system and status of the overall system, essentially the human interface. Part of the OIG is the data set manager, a stand-alone entity that operates at flight centers, as a software and hardware tool to provide the planning data and mission data that is loaded onto FAB-T both in the aircraft and the command centers.

Antenna Group

Rockwell Collins is also providing the RF pieces on the antenna side that interface the antenna group to the modem processor group.

For Global Hawk in Increment 2, major differences arise not least in the self-evident elimination of the operator’s interface group. Global Hawk will require a fuel-cooled rather than air-cooled system for FAB-T, which is different from other platforms. The UAV’s current Ku-only reflector will increase in size from a 28-inch to a 48-inch Ka/Ku dual capable solution.

The chassis will also be shrunk from Increment 1’s 6U size to a 3U solution while using existing hardware components. The 3U form factor will become the standard form factor for future increments. FAB-T common software will be used to instantiate new waveforms comprising standard CDL, KU SE-CDL and Mil-STD-188-165 Ka and HDR-RF Ka.

“We are trying to back up and take a holistic view of all the platforms in the current FAB-T operational requirements document,” said Dodd. “What we are trying to do is back up and lay out a family concept that leverages both the GH design and the Increment 1 design, so we can maximize hardware/software reuse to those other platforms and then try to minimize the number of unique antenna solutions that we have to provide. We are trying to get by with three to four terminal configurations and three to four antenna configurations for the entire family of platforms, and in order to do that you end up having to compromise on data rates and those types of things. Antenna designs are driven by the platforms and real estate of the fuselage.”

Back in the 1980s, Rockwell Collins, together with Raytheon, developed and fielded the existing command post terminals that the Air Force uses today.

“We bring along a legacy of Milstar experience that dates back to the 1980s, starting with the command post terminals program,” recalled Jim Barcz, satcom programs manager, Rockwell Collins Government Systems. “In the mid 1990s, we received a contract from the Army to build SCAMP, a man-portable EHF terminal that would operate using LDR. Over 600 of those systems were acquired in the late 1990s and early 2000s.”

A version that would support XDR was funded until 2004 by the Army.

While Increments 3 and 4 are planned developments of the program, demand for FAB-T’s additional platform has led to discussions of what has been dubbed Increment 2 plus. “We have significant interest from the fighter community, for the F-22 and F-35. Those are both looking at EHF BLOS because of its inherent LPI/LPD/Anti-jam capability. The platforms that control those fighters—E-3, AWAC and JSTAR—are also looking at these capabilities but they also want other capabilities: CDL and the possibility of using Ka and WGS. We are designing Increment 2 that can transition to those other platforms.”

Platforms outside the U.S. are also a possibility. “I will say right up front there was some thought early on as to whether or not this would be an international partner program, similar to the Navy’s NMT and the Army’s SMART-T and SCAMP programs,” said Cynamon.

Under an agreement, Canada, the Netherlands and United Kingdom have signed up to use the AEHF feed using these terminals. “Increment 1 does not [cover this], but it does not preclude the possibility that future increments of FAB-T could have international partners,” he added. ♦