The U.S. Air Force said Nov. 30 it expects no interruption in GPS services as it begins a transition to a new block of ground-control software for the fleet of timing and navigation satellites.

The Air Force’s fleet of 30 operational GPS satellites is currently flown using the GPS Operational Control Segment, which was designed and built by Boeing Defense, Space & Security of St. Louis. By 2015, control of the GPS fleet will transition to a next-generation ground segment, dubbed GPS OCX, that is being designed by Raytheon Intelligence and Information Systems of Aurora, Colo., under an $886 million contract awarded in 2009. In the meantime, the Air Force continues to upgrade the Boeing-built GPS Operational Control Segment.

When the most recent software upgrade was implemented in January, thousands of military GPS receivers were found to have incompatibility issues with the modified signals they were receiving. The Air Force scrambled to contract with the manufacturer of the affected GPS receivers to help track down the hardware and implement an interim fix within one month of the problems being identified, service officials said.

For the next ground segment update, set to begin this month, a thorough test regime has been performed and no anomalies were found, Col. Harold Martin, chief of Air Force Space Command’s position, navigation and timing division, said in a press release. The upgrade is expected to be complete in January 2011.