The USAF released the 5th Edition of the GPS Standard Positioning System (SPS) Performance Standard (PS) on 16 April.
This first update to the SPS PS since 2008 now includes pre-Initial Operating Capability (IOC) performance standards for new civil GPS signals L2C and L5, in addition to L1 C/A. It specifies the levels of SPS performance in terms of broadcast signal parameters and constellation design.
USAF reminds us that, since GPS initial operational capability (IOC) was first declared in 1993, actual performance has continuously met and exceeded minimum performance levels specified in the SPS PS, and users can generally expect improved performance over the minimum levels described in the Standard. For example, with current Signal-in-Space (SIS) accuracy, well-designed GPS receivers have been achieving (95%) horizontal accuracy of 3m or better and vertical of 5m or better.
It adds that any use of the pre-operational signals L2C and L5 is at the users’ own risk until those signals are declared fully operational and incorporated as operational signals in future editions of the SPS PS.