Raytheon, L-3 team on AESA demo

Paris Air Show » 2007
June 13, 2007, 11:16 AM

The advent of the active electronically scanned array (AESA) radar has not only dramatically improved the traditional capabilities of the radar, but has also opened the door to a new world of capabilities. Here at Paris Air Show this week, Raytheon–which builds AESA radars for the F-15 Eagle and F/A-18 Super Hornet fighters–and its partner L-3 Communications are highlighting the capability of using the AESA system to send large image files around the network in near real time.

Thanks to AESA, today’s state-of-the-art fighter can produce high-resolution synthetic aperture radar (SAR) imagery from considerable stand-off distances, greatly aiding the targeting process. While such maps can be used onboard the aircraft, the challenge until now has been in sharing that information and imagery. At worst, the crew can describe targets over the radio, while the adoption of Link 16 has allowed the passage of information between platforms, but is very limited in its data flow.

Using the AESA antenna as a transmission device allows huge files–such as SAR maps–to be sent very rapidly. Data can be shared with numerous platforms and command centers, and can be uplinked to satellites for wider distribution. Other files, such as EO/IR images, can also be pushed through the antenna. This way the AESA-equipped fighter can become not only an improved-capability tactical asset, but also an important platform for nontraditional intelligence, surveillance and reconnaissance (ISR). “Now we will be pushing information into the system, rather than pulling it out,” said Dave Goold, director of business development for the F/A-18 program and a former pilot. “The system will be a key node in the netcentric battlespace.”

According to Mike Henchey, business development executive at Raytheon Tactical Airborne Systems and a former F-15 pilot, the technology has changed everything. “Now you can share the entire map, not just the coordinates, and it can be shared in a fraction of a second,” he told Aviation International News. Furthermore, the system can operate largely in “machine-to-machine” mode, automatically transmitting and receiving information and so freeing the crew from having to operate it.

Saving Time
In the roadmap set out by the Pentagon, the aim is for a networked battlespace in which movements can be monitored and understood in near real time. To complement this, the kill-chain time has to be drastically cut to handle emerging targets.

On detection of such a target, the aim is to reduce the time required to gather information, identify it, approve a course of action and then carry out that action in less than 10 minutes.

As the process will almost certainly involve participation of command and control centers, and since a different platform may be used than the one that originally made the detection, the ability to move large amounts of information quickly is critical to the military’s aim of reducing the time for the whole process.

Among the many key applications for the technology will be in the forward air control, or FAC-A, mission. The ability of the FAC-A in one aircraft to pass annotated imagery to other strike aircraft will speed and enhance targeting, and will help clear the “fog of war” by reducing the ambiguities that can be created when targeting information is transmitted over the radio or alphanumerically.

The system is integrated with the overall sensor/weapons package, so when annotated target images are received they show up on the receiving crew’s displays and automatically cue the receiving aircraft’s sensors. The job of refining the target coordinates and verifying the target’s identity can be performed much quicker and with less potential for confusion than is currently possible. Another advantage is that the imagery produced by the FAC-A platform’s sensors is instantly familiar to other tactical fighter crews, which is not always the case with imagery from traditional ISR assets such as the J-STARS.

Using the radar as a communications device does not inherently affect the radar’s primary tasks. If the radar array is used on its own as a communications device, then it follows that the communications can be performed only over the radar’s field of view in the forward hemisphere of the aircraft. Raytheon’s studies show that this will not be a problem, as aircraft in the battle area maneuver sufficiently that the ability to communicate is not compromised to any great extent. This is aided by the automatic nature of the communications. In the Super Hornet, the system is fully integrated with other systems such as the passive radar warning receiver, effectively giving the system full 360-degree coverage.

To develop this new capability, Raytheon joined forces with L-3 Communications to marry AESA technology with L-3’s expertise in communications and datalinks. L-3 already has a proven waveform and algorithms, speeding the development time, and it also has experience in a wide range of ground stations, including the Rover system currently used to downlink images to ground units.

This ground-breaking AESA communications technology was demonstrated last December using Raytheon’s flying testbed. The AESA-equipped aircraft took a high-resolution SAR image, transmitted it through the antenna to a ground station, where the image was annotated with target information before being uplinked back to the aircraft. The data transfer of this many-megabyte image took just 80 milliseconds. Raytheon emphasized that, following the successful tests last year, the technology is ready to go, and it hopes to see it fielded in two to three years.

Although ITAR export regulations prevent Raytheon from a full demonstration of its technology, it is staging a display here at Le Bourget that hints at some of the capabilities, with a camera on the flight line sending images back to the exhibition area.   

Raytheon AESA Updates

• F/A-18E/F Super Hornet–Having returned to Pacific Ocean in March 2006 from the last cruise of the F-14 Tomcat, the “Blacklions” of VFA-213 began transitioning to the F/A-18F to become the first U.S. Navy squadron with AESA-equipped Super Hornets. The squadron was declared “safe for flight” on October 27 last year and is now in a work-up cycle preparing for the first deployment early next year. Further APG-79 AESA units are being formed, initially on the U.S. West Coast. Earlier this year, the Royal Australian Air Force opted to purchase 24 Super Hornets, which will be equipped with APG-79.

• F-15C Eagle–Having gained experience with 18 F-15Cs equipped with the APG-63(V)2 AESA radar in Alaska since 2000, the U.S. Air Force is seeking to upgrade the remaining 160 fighter Eagles it intends to keep in service. In 2006, the first six AESA antennas for upgrading Air National Guard aircraft to APG-63(V)3 standard were ordered. Late last month, the Fiscal Year 2007 Global War on Terror supplement was authorized, with funding included for APG-63(V)3 antennas to begin upgrading the active-duty fleet. Compared to the (V)2, the (V)3 has an improved antenna array based on that of the APG-79.

• F-15E Strike Eagle–The U.S. Air Force is currently undertaking a competition to put AESA radars into its 220-plus F-15Es. Raytheon is offering a spiral evolution beyond the current APG-63(V3) AESA now in production for the F-15C and International F-15E aircraft. A decision on the competition is expected this fall, leading to the start of low-rate initial production in around four years.   

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