In 1998 The Vice President and the White House make an announcement to modernize the GPS system. In 2000, U.S. Congress authorized the project, referred to as GPS III. The project involves new ground stations and new satellites, with additional navigation signals for both civilian & military users, and aims to improve the accuracy & availability for all world-wide users.

The target date is 2013 with incentives offered to the contractors if they can complete it by 2011.

New Navigation Signals

• Civilian L2 (L2C)
  The L2C signal is tasked with providing improved accuracy of navigation, providing an easy-to-track signal, & acting as a redundant signal in case of localized interference.
• Military (M-code)
  The M-code is designed to be autonomous meaning that a user can calculate their position using only the M-code signal. While the full Earth M-code signal is available on the Block IIR-M satellites, the spot beam antennas will not be available until the Block III satellites are deployed, tentatively in 2013.
• Safety of Life (L5)
  Safety of Life is a civilian-use signal, broadcast on the L5 frequency (1176.45 MHz), planned to be implemented with first GPS IIF launch (2008). Improves signal structure for enhanced performance; Higher transmission power than L1 or L2C signal; Wider bandwidth; Longer spreading codes
• New Civilian L1 (L1C)
  L1C is a civilian-use signal, to be broadcast on the same L1 frequency (1575.42 MHz) that currently contains the C/A signal used in all current GPS system. The L1C will be available with first Block III launch, currently scheduled for 2013. Enables greater civil interoperability with Galileo L1;

(g-spot, wikipedia)