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What is the civilian C/A-code used by Navstar GPS satellites?
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GPS
U.S. Navstar Global Positioning System (GPS) satellite in orbit over Earth, shown in an artist's conception.
The civilian C/A-code (coarse acquisition code) used by Navstar GPS satellites is a 1-megabit-per-second pseudo-random binary pulse train.1
This code modulates the carrier wave at 1575.42 megahertz to provide positioning data to civilian users. While it was previously subject to intentional degradation known as selective availability (S/A) to limit accuracy for non-military purposes, that feature was terminated in 2000 to improve safety for civilian aviation and maritime navigation. Currently, unaugmented civilian GPS typically provides horizontal accuracy of about 10 metres (30 feet).1