Intelligence Upgrade

By Frank Colucci | April 1, 2009
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Just how valuable the intelligence gathered by the RC-12 Guardrail aircraft is to U.S. Army ground commanders is rarely disclosed.

The ground-based Guardrail system uses airborne receivers to collect signals intelligence (SIGINT) and geolocate enemy communications and radar emitters in near real-time. Linked by satellite to an Integrated Processing Facility at Fort Hood, Texas, the antenna-spiked turboprops of the 15th Military Intelligence Battalion (Aerial Exploitation) were the first manned intelligence collection platforms to fly combat missions over Iraq in 2003. Guardrail intelligence has been credited with saving coalition lives in Afghanistan as well.

The Army’s 43 RC-12s nevertheless represent four different configurations, all growing dated and difficult to maintain. Northrop Grumman Mission Systems, Intelligence Systems Division, is under Army contract for a Guardrail modernization that will bring 33 of the existing aircraft to a common standard and dramatically enhance their signals collection and targeting capability. The company in 2007 was awarded a five-year contract valued at up to $462 million for Guardrail Modernization system integration.

"The likelihood we will intercept the bad guys is better," summarized Michael Madden, deputy project manager for Aerial Common Sensors at the Program Executive Office – Intelligence Electronic Warfare and Sensors. The Army Communications and Electronics Command (CECOM), headquartered at Fort Monmouth, N.J., is responsible for the new Guardrail mission equipment package. The Army Aviation and Missile Command (AMCOM) in Huntsville, Ala., is managing a concurrent cockpit upgrade.

Guardrail modernization includes Northrop Grumman conformal antennas and aircraft structural upgrades installed by Hawker Beechcraft, manufacturer of the military King Air/Huron.

"It’s pretty much refreshing the whole thing," said Mark O’Neill, project manager for Aerial Common Sensors and product director for Aerial Intelligence, Surveillance, and Reconnaissance Systems.

The first modernized RC-12N1 (formal RC-12S designation awaits Air Force approval) should fly in June. The First Unit Equipped with four modernized aircraft is expected in the second or third quarter of 2010, and the entire zero-timed, mission-enhanced fleet should be complete by the fourth quarter of 2013. With the joint-service, jet-powered Aerial Common Sensor cancelled in 2006, the renewed Guardrail will be a valuable intelligence collection asset beyond 2020.

Common Standard

Guardrail has evolved since 1971, migrating from the RU-21 to the RC-12 platforms and advancing through Improved Guardrail and Guardrail Common Sensor stages aboard the RC-12D, H, N, P, and Q aircraft.

The Guardrail concept of operations has remained unchanged through the iterations. A crew of two flies an aircraft full of intercept receivers that are controlled from the ground. To cover larger areas and locate enemy emitters precisely in signal-rich environments, two or three aircraft operate in concert, linked to a Guardrail Ground Baseline (GGB) by a Ku band Tactical Common Data Link from L3 Communications. (The Airborne Overhead Cooperative Operations initiative tied a single Guard Rail Common Sensor aircraft to National Reconnaissance Office assets for precision location deep in hostile territory.)

The GGB in turn uses a Tactical Satellite Terminal to relay collected signals to garrison operators and analysts and send receiver commands to the aircraft in flight. Analysts and interpreters back home turn the collected signal data into actionable intelligence for ground commanders.

Each Guardrail Common Sensor version required a different ground station. The RC-12S modernization wipes out the distinctions between versions. "It’s just Guardrail," said O’Neil.

GGB stations that were once unique to the different versions are being modernized by Northrop Grumman to common GGB 2.0 standard. The company last October announced the successful fielding of the 2.0 software, which provides enhanced data processing capabilities for signal analysis and command and control of the Guardrail payload. The feat was described as an important step toward migrating GGB into the Distributed Common Ground Station-Army (DCGS-A). Participating companies were L3 Communications-ILEX Systems, Eatontown, N.J., L3 Communications Systems West, Salt Lake City, and CACI Technologies, Arlington, Va.

"At the end of it, all the aircraft will have a common infrastructure across the fleet," O’Neil said. "Once we have all common aircraft and common GGB, any aircraft can work with any GGB."

Common tools and capabilities promise economies in Guardrail operations and training across the fleet. New airborne hardware with modern Built-In Test capability should also speed troubleshooting and enhance availability.

Different Guardrail systems remain home-based in the United States, Germany and Korea. The original Integrated Processing Facility (IPF) vans have given way to Sanctuary facilities with standard Guardrail Information Nodes for co-located operators and analysts of the Aerial Exploitation Battalion.

Separate from the airborne modernization, ground improvements are continuing. Sun Blade 150 workstations introduced about four years ago in the ground centers may be replaced by a common PC-based solution, and CECOM is working with the National Security Agency on common intelligence tools.

More Channels

New receiver and processor technology in the airborne portion of Guardrail promises to enhance the performance of the entire signal collection system.

"You’re at max power, max weight, max cooling," said Clark Lewis, program manager for Army airborne intelligence, surveillance, reconnaissance programs at Northrop Grumman Airborne Systems Division, Mission Systems Sector. "To evolve, we had to throw some things overboard. We removed some systems that were 10-plus years old and replaced them with wideband technology."

The new Guardrail common receiver package expands the frequency coverage and the types of signals collected with a high-band receiver. "We’re probably increasing receiver capacity 10 times, so you’ll be able to collect more information," said O’Neil.

Improved ability to work in co-channel environments also means the receivers will be able to pick up signals and filter out noise in dense urban areas. The new Guardrail can capture more than 70 channels but remains limited by the existing 20 Mbit/sec downlink.

Increased signal throughput and new signal types require a new Guardrail processing architecture, one able to handle multiple signals simultaneously. Northrop Grumman adapted Airborne Signal Intelligence Payload (ASIP) technology developed for the Air Force U-2 and Global Hawk unmanned aircraft to the RC-12. The scalable ASIP flew on an RC-12 last June and demonstrated intercept and direction finding capabilities by integrating the new ASIP with an off-the-shelf Embedded GPS/Inertial navigation system and existing antenna arrays.

Guardrail modernization supplements the modified RC-12N antenna farm with new aerodynamic conformal antennas on the aft fuselage and wing pods to expand the system field of view and depression angles. "Now you can almost overfly targets," Lewis said.

Signal geolocation improves with CHALS-C, the latest Communications High Accuracy Location System. Today’s Guardrail has a single-channel CHALS and an obsolete inertial navigator derived from a helicopter application. The new four-channel CHALS-C archives data in multiple channels simultaneously and works with the embedded GPS.

Guardrail payloads today are collections of 15 to 18 hard-wired boxes. The RC-12S modernization guts the aircraft and integrates far more capable systems on a Mil-Std-1553 data bus. The data bus gives all the airborne systems from different suppliers common time and navigation references to enhance Guardrail precision location capability. "We now all have the same perspective," said Clark.

The data bus architecture also will help Guardrail stay relevant until the introduction of a new Aerial Common Sensor or unmanned aircraft system. "In the future, we’ll be able to plug in new capabilities easier than we did previously," O’Neil said.

Northrop Grumman will integrate and install all the mission elements of Guardrail modernization in Sacramento, Calif., after the aircraft undergoes a comprehensive cockpit upgrade.

A new glass cockpit compliant with Global Air Traffic Management requirements will be installed by Stevens Aviation in Greenville, S.C. The package was designed in 2007 by the AMCOM Fixed Wing Program Management office, leading an avionics working group from Stevens Aviation, Universal Avionics, and DynCorp International.

The Guardrail cockpit modification marks a significant improvement over the previous ILS, VOR, TACAN and NDB suite and INS navigator in the RC-12. It integrates COTS components, including three 8-inch-square Universal Avionics EFI-890R primary flight/multifunction displays, dual UNS1F/WAAS flight management systems, a Rockwell Collins AHS-3000 Attitude and Heading Reference System, Trimble TASMAN TA-12S SASM GPS, Universal UNILINK, Rockwell Collins TWR-850 turbulence/weather radar, Honeywell Enhanced Ground Proximity Warning System, and two Thommen AC-32 digital air data computers. The cockpit package includes an Altair Avionics Aircraft Data Acquisition System (ADAS) for engine trend monitoring and L-3 Communications GH-3100 electronic standby instrument system.

Guardrail is a valuable Army system in the Global War on Terror. All of the RC-12s in the combat theaters have been equipped with BAE AN/AAR-57 Common Missile Warning Systems and ALE-47 Improved Countermeasures Dispensers to protect them from IR-guided surface-to-air missiles.

The modernized Guardrail will be an even richer source of close-kept intelligence. Even Northrop Grumman is denied feedback about Guardrail’s combat performance.

"We certainly don’t get anything directly," said Clark. "Indirectly, our schedules are predicated on returning these limited assets to the field quickly because they’re needed."

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