The Defense Department approved the next-generational Operational Control System of the Air Force’s Global Positioning System constellation to enter the engineering and manufacturing development (EMD) phase, according to the Air Force.

Under Secretary of Defense for Acquisition, Technology and Logistics Frank Kendall signed off on Milestone B on Oct. 11, having found the Air Force and sub-contractor Raytheon [RTN] successfully met all requirements for the Operational Control System, also known as OCX, to enter into the EMD phase. OCX will replace the current GPS system’s Operational Control Segment in managing the current constellation and providing the capability to control the GPS family of satellites, including IIR-M, IIF and the new GPS III satellites.

OCX is being developed and fielded in major “blocks” of GPS capability to align with GPS III and military equipment deliveries. The Launch and Checkout System, scheduled to be available in the fourth quarter of 2014, will allow OCX to support the launch of GPS III satellites. The Launch and Checkout System is also known as Block 0.

OCX Block 1, scheduled for operation in the first quarter of 2016, will deliver the operational capability to command and control (C2) the entire GPS constellation. This block will also control the legacy civil and military signals as well as two modernized civil and military signals, L2C and L5.

OCX Block 2 will specifically support advanced capabilities for civilian and military signals, the international civil signal (LC1) and the military signal M-Code. OCX Block 2 is “currently synchronized” with modernized signal broadcast and timing, the Air Force said.

Raytheon spokeswoman Kim Warth said the company is the prime contractor developing OCX for the Air Force while fellow contractor Lockheed Martin [LMT] is a prime contractor on space development. Raytheon is delivering the actual OCX system while Lockheed Martin is verifying it.