Australia helps beat GPS jamming

The GPS navigation system may become more reliable and useful during a conflict as a result of trials Australian and US defence scientists conducted at Woomera earlier this year, which demonstrated that the vulnerability of Global Positioning System (GPS) receivers to interference can be greatly reduced.

The GPS Jammer Locator (JLOC) trials were a joint demonstration between the United States Air Force Operational Test and Evaluation Centre (AFOTEC), and Australia's Aircraft Research and Development Unit (ARDU) the Defence Science and Technology Organisation at Salisbury in South Australia, and Air Services Australia (ASA)

DSTO scientists taking part in JLOC trials

The JLOC system, under development through a US Air Force Research Laboratory (AFRL) contract to the American company NAVSYS, is designed to locate GPS jamming/interference sources and provide data to tactical/strategic planners to assist in defeating these sources.

GPS is used in a very wide range of applications that include air, sea and land navigation, intelligent transportation systems, mining, and agriculture, as well as in telephone and electrical power grid synchronisation. In consequence its smooth operation is critical. However, it is highly susceptible to both electromagnetic interference and environmental phenomena, which can seriously impair its performance for both military and civilian operations.

"GPS receivers can be rendered ineffective with simple, inexpensive, pocket-sized jammers deliberately designed for the purpose, or coincidentally by TV antennas, radars, and communications towers," said DSTO's Dr Anthony Finn (former GPS head with DSTO)

"The aim of the trials at Woomera was to show that it is possible to locate and identify GPS interferers. The JLOC system was used to locate ground based GPS interferers provided by the DSTO from a combination of ground and airborne platforms," added Finn.

The trials also proved that there were a number of methods that would reduce receiver vulnerability.

"The experiment was also a turning point in DSTO's involvement in GPS research with the Americans because we were able to demonstrate our knowledge and expertise in this area and contribute high quality interference equipment to the trials," says Finn.

Woomera was selected for the trials because it is becoming prohibitively expensive for the Americans to mount trials of this scale in the US because of the impact they would have on the civilian infrastructure that is dependent upon GPS.

Woomera has an area of up to 450 kilometres radius which is relatively free from other GPS users, enjoys clear weather and has good airfield and support facilities allowing several aircraft the freedom to fly around the Woomera region locating multiple interferers on the ground.