Air Force Adds Navigation Data to Modernized Civil GPS Signals
On April 28, 2014, the Air Force began broadcasting civil navigation (CNAV) messages on all operational GPS satellites capable of transmitting the L2C and L5 signals. L2C and L5 are the first of several new civil capabilities being added to GPS as part of the GPS modernization program announced in 1999. L2C and L5 are currently pre-operational signals to be used primarily for testing equipment, not for safety-of-life or other critical purposes.