Tracking New Directions

Interference suppression, or anti-jam technology, is critical terminology in modern warfare.

It’s a force-protection measure that ensures assured positioning, navigation and timing (APNT) in GPS degraded and denied environments for its ground-based troops.

GPS Source, a subsidiary of General Dynamics Mission Systems, is a trusted provider of these vital capabilities, delivering APNT kits with anti-jam and anti-spoof capabilities that can be mounted on equipment by soldiers.

What makes these kits especially valuable to ground-based soldiers is the GPS Anti-Jam Technology (GAJT) from Hexagon | NovAtel which packs a very big punch.

Jammed up

As the potential for jamming signals has risen along with the number of at-risk systems, anti-jam technology has also begun to evolve, with an emphasis on protecting GPS signals against peer and near-peer adversary Cyber Electromagnetic Activities (CEMA).

In search of advanced APNT solutions, including the DAGR Distributed Device (D3) PNT hub and the ECHOII GPS indoor retransmission smart amplifier, and many other military grade components that receive, disseminate and rebroadcast GPS data.

David Jones, solutions architect, GPS/APNT Products with GPS Source, said: “During the development of the prototype, we were testing our assured PNT system with different antennas. We hadn’t worked much with NovAtel prior to this, but we really liked the look and feel of their antenna.”

The GAJT-710ML consists of an antenna array and null forming electronics inside a hardened enclosure for a wide range of land vehicles. This commercial off-the-shelf anti-jam antenna is designed for land, sea and fixed installations.

NovAtel’s GAJT-710ML detects unwanted interference and makes nulls in the antenna radiation pattern in the jammer’s direction, which prevents the jamming signal from overpowering the antenna and receiver electronics, ensuring a position can still be computed.

“The GAJT-710 has good performance and integrates very well with our system,” Jones added.

THE SYSTEM INCLUDES:

• Enhanced D3 (ED3) Receiver—Distributes centralized ISGPS-153 and MSID messages to up to eight independent, unique interfaces. the newest D3 Devices can provide SAASMcor M-code-protected GPS.
• NovAtel’s GAJT-710ML Anti-Jam Technology—Mitigates impact of enemy jammers and protects the ED3 Receiver (SAASM/MCode) and can also protect Galileo E1 and QZSS. A second fixed reception pattern antenna (FRPA) feeds a receiver for other GNSS, and the signals are managed by the Anti-Jam Antenna Integration Module (AJAIM).
• VICTORY CSAC Accessory Module (VCAM)—Contains a Chip Scale Atomic Clock (CSAC) and software designed for electronic surveillance/electronic protection (ES/EP) and allows for integration of other solutions such as an inertial navigation system (INS) and anti-jam antennas.

Jones and his team modified the hardware to communicate with GAJT and collect the data. By the end of 2019, the prototype was ready for field testing.

Easy configuration

The APNT kits with GAJT-710ML’s are designed for military vehicles. Initial deliveries were in the fall of 2019 for testing, feedback and integration.

Jones explained: “It’s a plug-and-play design so it’s easy to install. Since each vehicle variant has a different configuration on the roof, a vehicle integrator worked with the to determine mounting locations and necessary hardware to support the kits to meet various requirements.”

The mounts, called stovepipes, are elevated off the vehicle on a pylon to give the antenna an optimal view of the sky.

Thus far, the has been pleased with the performance of the APNT kits. The organization subsequently submitted orders for many additional systems that have now been installed on ground vehicles.

Finding direction

Looking forward, Jones sees continued evolution of capabilities for the APNT kits including enhanced situational awareness. “This functionality would help the operators identify and locate jamming signal sources for greater response,” he said.

The newer generation of GAJT technology, which includes the GAJT-410ML and the next generation GAJT-710ML, will support additional functionality such as situational awareness to better characterize RF signals, Jones added, “The military is very excited to have situation awareness capability as it will open up a lot of opportunity.”

Success with the APNT kits has sparked interest in the versatile anti-jam solution across all branches of service. GPS Source expects to test the GAJT solution in other conditions for other applications in the future.

Jones concluded: “We have found the antenna to be [a] very competent solution. For heavy armor vehicles, the GAJT-710ML is the best choice.”

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