GAJT (pronounced “Gadget”) is the first single unit GPS anti-jam antenna appropriate for use with military land vehicles, networks and timing infrastructure. GAJT nullifies jammers, ensuring satellite signals necessary to compute position and time are always available.
GAJT provides anti-jam performance comparable to much larger systems, but at a significantly lower cost. GAJT is a Commercial Off-the-Shelf (COTS) product, providing short order lead times and quick deployment. It easily integrates into new vehicle platforms or can be retrofitted with GPS receivers and vehicle navigation systems on existing and legacy military fleets.
- Commercial Of The Shelf (COTS)
- 7 antenna elements create 6 independent nulls
- Simultaneous GPS L1 and L2 with an upgrade path for other GNSS constellations
- M-Code ready (24 MHz bandwidth)
- Immediate availability for urgent operational needs
- Simple assembly means easy to install or retrofit
- Compatible with existing GPS receivers and vehicle navigation systems
- Non-ITAR product to ease export to authorized customers
- Minimal integration training required
Antenna Form Factor
LNA Gain (dB)
|The first single unit GPS anti-jam antenna appropriate for use with military land vehicles, networks and timing infrastructure|
Antenna Form Factor
How it works
Protects Position; Saves Lives
GAJT's proprietary technology uses a concept similar to that of noise-cancelling headphones; it nullifies the jammers that are trying to overpower the satellite signals that GPS positioning systems use to compute location. GAJT defeats jamming thanks to antenna elements that create up to six independent nulls in the direction of the jammers. With the jammer nullified, your receiver is clear to acquire and track the GPS signals you need to ensure accurate battlefield position.
Without GPS anti-jam technology, a simple 1-watt jammer can overpower GPS signals within a large area, denying a position solution from the victim receiver. GAJT improves the GPS jamming immunity of the connected receiver, significantly decreasing the reach of the jammers, ensuring that positioning capabilities are retained during combat, training or other vehicle based missions.
Without GAJT, operational positioning is lost
With GAJT, operations proceed unobstructed
Successfully tested by both the Canadian and British military, GAJT leverages the proven expertise of two technology leaders known for their products' performance and reliability. Military personnel can depend on GAJT to help maintain situational awareness, protecting soldier's lives and improving strategic battlefield performance.
Jammers prevent determination of vehicle position and time.
GAJT generates antenna “nulls” to
GAJT generates multiple nulls to defeat
Instant anti-jam protection
The compact, efficient design of the GAJT antenna makes the addition of anti-jam capability to existing and new vehicles easy. GAJT is externally mounted, requiring no additional electronics inside the vehicle-only power and a single RF cable.
Vehicle with typical GPS system and
GAJT requires only power and
existing antenna cable
With minimal vehicle alterations required, operator training is unnecessary because the original GPS unit remains in place.
The self-enclosed GAJT provides an all-in-one solution unlike other anti-jam devices that typically feature more than one component. This results in faster installation, minimizes vehicle downtime and installation training, and makes it easy to integrate or retrofit into existing and legacy fleets.
Big impact in a small package
GAJT is an active antenna based on a 7-element controlled reception pattern antenna and null-forming algorithm. The antenna adapts the reception pattern to reduce the gain in the direction of malicious and accidental jammers. Incorporating NovAtel's patented 7-element Pinwheel™ antenna, seven independent copies of the GPS L1 and L2 frequencies are acquired from seven different locations within GAJT's radome. These are then down-converted to intermediate frequency for high-speed digital sampling and processing by QinetiQ's proprietary null-forming algorithm. This optimizes the power and phasing of the seven independent signals to create a single, high quality output signal. The output is then up-converted to the original GPS frequencies. The clean output signal is delivered through a standard TNC connection, via coaxial cable, to the antenna input port on new or legacy GPS receivers.
GPS & Jamming
GPS technology has revolutionized modern warfare. It is now regularly depended on for accurate positioning, targeting and communications. For information on how GPS and other satellite systems of the Global Navigation Satellite System (GNSS) operate, refer to our book “An Introduction to GNSS: GPS, GLONASS, Galileo and Other Global Navigation Satellite Systems”.
While the value of GPS is unquestionable, the increasing availability of jamming technology is proving problematic. GPS signals are transmitted on published radio frequencies from satellites that orbit 20,000 km above the earth. The GPS transmit levels from the satellites are extremely low power, and are only about 50 x 10-18 W by the time they reach the surface of the Earth. This fundamental weakness makes the signals vulnerable to both accidental and deliberate interference. Although illegal, devices that jam GPS signals are easy to obtain. Simple models that plug into 12-volt car receptacle connectors can be purchased for as little as $30 online and can render GPS systems inoperable for miles around.
Instances of recent GPS jamming include:
- GNSS Jamming in the Name of Privacy: Potential Threat to GPS Aviation
- Recent report of North Korean GPS jamming capability
Learn more about GPS Jamming:
- GPS chaos: How a $30 box can jam your life
- Warning on GPS jamming threats
- Academy report warns of over-reliance on global satellite navigation systems
- No Jam Tomorrow
- GPS Jammers Could Wreck Transport, Communications
- National PNT Advisory Board comments on Jamming the Global Positioning System - A National Security Threat: Recent Events and Potential Cures
- The Civilain Battlefield - Protecthing GNSS Receivers from Interference and Jamming
- “Managing the Integration of Space and Information Operations” Maj Daniel F. Gottrich, USAF and Michael R. Grimaila, PhD, AFIT; High Frontier, April 2006 Volume 2, Number 3
- US Department of Defense, “Global Positioning System (GPS) 2008, A Report to Congress” dated 31 Oct 08.
- KTN event: “GPS Jamming and Interference - A Clear and Present Danger” 23 February 2010, National Physics Laboratory, Teddington