P-code

The "protected" or "precise" code used on L1 and L2 GPS bands. The U.S. DoD only makes this code available to authorized users. The P-code is bi-phase shift modulated on both the L1 and L2 carrier frequencies. P-code has a 10.23MHz bit rate and, as implemented in GPS, has a period of one week. Each satellite has a unique P-code that is used to distinguish a satellite from all other satellites.

The P-code is replaced by a Y-code when Anti-Spoofing is active.

See also Y-code.