The US Air Force has awarded a modified contract for 81,622 defence advanced global positioning system receiver (DAGR) units and accessories to Rockwell Collins.

The present $20.2m contract modifies a $450m DAGR follow-on contract received by the defence firm in March 2009.

The DAGR is a hand-held device mostly used by the US Army for position, navigation and situational awareness functions. The receiver aids in synchronising tactical radios, missile platforms and other navigation systems.

The device incorporates anti-jam improvements and denied GPS capabilities for enhanced battlefield protection.

The DAGR also features a selectively available anti-spoofing module.

The modified contract will exercise 30 options from the follow-on contract and will be managed by the US Air Force GPS Wing at El Segundo.