Gripen E’s Electronic Wizardry Is The Future

If the Gripen E/F programme had a mantra it would probably be ‘high capability at low cost.’ This central theme means that Gripen NG development has been ruthlessly focused on producing an aircraft that has enhanced sensors compared not only to the preceding Gripen variants, but also to contemporary ­ fighters worldwide.

To this end, Saab and its partners have invested heavily in cutting edge technologies such as gallium nitride (GaN) for sensors such as AESA radars and electronic warfare (EW) systems. While the Selex AESA uses proven gallium arsenide (GaAs) technology for its transmit/receive modules, the Gripen E/F will feature a GaN-based EW suite that provides tremendous situational awareness. It is signi­ficant that both Selex and Saab have thrown their weight behind the new GaN technology, which is expected to enable more powerful and yet more reliable AESA antennae as compared to those that use existing GaAs modules. Additionally, with the impending proliferation of low-observable combat aircraft around the world, Saab has incorporated a Selex Skyward-G infrared search and track (IRST) sensor and a new IFF (identi­fication friend-or-foe) system.

The Selex Raven ES-05 AESA radar is the ­first production AESA in the world to be mounted on a rotating swashplate, vastly improving the radar’s ­ field of view. Most AESA arrays are ­fixed and therefore have a fixed field of view, which is often considered quite narrow when compared to older mechanically-steered radar arrays. However, the range and instantaneous scanning ability of AESA radar sets make them tremendously attractive in modern day combat. Combining the two – AESA performance and mechanical steering – gives the ES-05 a much larger ­field of view than comparable arrays, estimated at over 100°. The new three-antenna IFF system provides low-latency coverage across the radar’s entire field of view and matches its maximum range, providing reliable information on targets within detection range of the Gripen.

The IRST employs a long-wave focal plane array sensor, also called a ‘staring array,’ with three ­fields of view. In long-range search mode, the system effectively behaves as an infrared telescope and in wide-angle mode it provides a night-vision image that can be projected on the head-up display (HUD). Being a passive sensor, IRST systems can only provide reliable azimuth and elevation data but the Skyward-G is also able to provide rudimentary range information via ‘kinetic ranging,’ wherein the aircraft performs a weaving manoeuvre and range to target is determined by the change in azimuth or elevation angles. Additionally, the IRSTs on two (or more) aircraft can triangulate range to target by sharing tracking information over their datalinks. Skyward-G is based on the Selex PIRATE system used on the Euro­fighter Typhoon, but by virtue of being newer, has seen more development on both the hardware and software fronts, allowing for better and more discriminate performance.   When all the new detection hardware, that is, the ES-05 radar, the Skyward-G IRST unit and the IFF system are employed together, the situational awareness provided to the pilot, including against low-observable targets, is remarkable. Crucially, however, the IRST adds a level of self-defence to engagements with low-RCS targets that other ­ fighters equipped only with AESA radars would lack. As a passive sensor, it emits no signals and is therefore undetectable as it scans for targets. Once a target is acquired, the IRST can continue to track it whilst undetected, waiting until the last possible moment to switch to an active (but detectable) sensor such as the AESA radar. With ‘lock on after launch’ (LOAL) technology, the IRST can even be used to guide a missile toward the target without using any active sensors at all, letting the missile seeker conduct terminal guidance to the target. Not only does this make the Gripen E/F an effective ‘counter-stealth’ platform at a very affordable cost, it also makes the platform much more survivable against any opposing ­ fighter – stealth or otherwise.

This level of sensor fusion and situational awareness makes for much more effective performance in various situations. For example, in the air defence role, a Gripen E can operate safely even among civilian traffic – the IFF system would handle information from friendly/commercial aircraft, freeing up the other sensors (radar, IRST) to track or engage unidenti­fied or hostile craft.

The Gripen Demo aircraft (39-7) has flown with both the ES-05 AESA radar and its swashplate mounting and the production-standard Skyward-G IRST system. The IFF system is expected to be delivered for testing sometime in 2014.

In addition to the on board EW and self-defence suite, the Gripen will also be the first aircraft to offer the new ‘BriteCloud’ off-board active decoy from Selex. BriteCloud is a self-contained Digital RF Memory (DRFM) jammer for ­ fighters, and was launched by Selex on 6 November 2013. Saab will offer BriteCloud as an electronic warfare option on all versions of Gripen.

BriteCloud is specifically aimed at defeating modern tracking systems, both ground-based and air-based. Its DRFM technology is able to defeat even contemporary chaff discrimination techniques, effectively creating a convincing false target that allows a wide range of threat systems to be countered.

As an off-board device, BriteCloud avoids the ‘home-on-jam’ vulnerabilities of on-board devices where the source of jamming itself acts as a beacon for hostile sensors and munitions to target. Additionally, since BriteCloud does all processing and transmitting inside the unit rather than on the platform, it is able to put a signi­ficant distance between itself and the ­ fighter after launch. This minimizes the risk of incoming missiles detonating in close proximity to the platform, further increasing the efficacy of the system.

 

Courtesy: Vayu