GPS L1 C/A

GPS L1 C/A is the open civilian signal of the United States NAVSTAR Global Positioning System, broadcast on the L1 carrier at 1575.42 MHz. C/A stands for Coarse/Acquisition: a 1.023 Mcps Gold pseudo-random code, unique per satellite, repeating every millisecond, that the receiver correlates to measure pseudo-range. The satellite navigation message at 50 bits per second carries the broadcast ephemeris, clock corrections, and almanac. A receiver solves for latitude, longitude, height, and clock bias from four or more satellites. Standalone L1 C/A gives roughly 5 to 10 m horizontal accuracy; DGPS or SBAS corrections tighten that to 1 to 3 m.