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Gripen E operations in GPS denied environment

3 min read

Consider a scenario: The GPS on a fighter aircraft in a hostile territory blacks out.

To be able to navigate with confidence and accuracy when GPS is unavailable for a long time is a game-changing capability for a fighter pilot. It sounds like a challenge - for others. Saab has studied and tested image-based and terrain navigation techniques and now propose new technology for powerful tactical navigation capability in GPS-denied environments.

Last year, Saab performed successful flight tests with Gripen E using new algorithms providing real-time and highly accurate positioning based on image mapping known as 3D-mapping. The tests, conducted in collaboration with Maxar, successfully proved the concept where data from on-board electro-optical sensors and geo-registration algorithms is compared with a 3D surface model database in the aircraft.

odometry and terrain navigation

Odometry and terrain navigation

The use of image mapping technology of odometry has also been tested previously with good results. Here an on-board sensor observes landscape features ahead and the algorithms generate a more accurate velocity vector and assist the inertial navigation system.

Terrain navigation, in which Saab has a long history, with for instance TERNAV, has also been tested previously in different demonstrations and this technology has evolved in-house with new algorithms and database-handling technologies.

Robust positioning with high accuracy

In this case, a camera on Gripen E captures a livestream of its flight path. Other sensors can also be used to scan the terrain if needed. By matching visuals in the livestream to the 3D data in real time, the algorithm can determine the fighter’s precise location, enabling the pilot to navigate and carry out the mission without GPS.

Maxar 3D Surface Model’s immersive 3D data is produced with automated technology, delivered rapidly and with high precision based on high-resolution satellite image with resolution of 50 cm or better and 3 m accuracy in all dimensions.

The chart across the top of the video indicates the accuracy of the the algorithm matching of the livestream video to the Maxar 3D Surface Model.

By combining these three technologies (3D-mapping, odometry and terrain navigation), the navigation system will provide the Gripen pilot with a disruptive and unique capability to operate in Global Navigation Satellite System (GNSS-)/GPS-denied environments with highly accurate positioning maintained.

The combined technologies provide a solution that is immune to GPS signal interference like jamming and spoofing efforts, and it doesn’t add to the pilot’s workload while flying. With its accurate positioning, Gripen thereby enables its pilots to counter the opponent’s use of anti-access/area denial tactics.

“In the world of modern war fighting, zero collateral damage, high precision and robust positioning is key to mission success. The tactical navigation technology in GNSS-denied environments will be a true game-changer in air operations,” says Jonas Jakobsson, Gripen Experimental Test Pilot, Saab.

Additional derived benefits

In addition to supporting the navigation, there are other potential derived benefits of this technology, such as building and executing targeting functions, and facilitating aircraft landings in challenging environmental conditions where normal landing aids are compromised.

“We are well ahead with this capability, and we recently demonstrated that with flight tests. We now take the next step to implement this technology in solutions for our customers. This would further add our already really strong offer for India, especially considering the IAF´s demanding mountainous and high-threat operational environment.” says Tobias Jansson, Product manager Gripen.