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coarse/acquisition (GPS) (C/A)

The C/A code (Coarse/Acquisition) is a special code for civilian use of satellite navigation systems where the resolution is reduced. This contrasts with the higher-resolution P/Y code (Precision Encrypted), which is used for military applications. The C/A code and the P code are transmitted over different GPS frequencies.

The C/A code is used in the GPS system and in the Global Navigation Satellite System( GLONASS). In the GPS system, it is obtained via pseudorandom numbers( PRN) as a 1, 023-bit long code from the 10.23 MHz frequency of the atomic frequency standard and repeats every millisecond. The C/A signal is transmitted using the spread-spectrum technique( DSSS) with a bandwidth of 2 MHz in the L1band. In this technique, the term chips is used instead of bits. These are the elements of a pseudo-random number.

Since the chip pattern repeats after 1,023 bits or 1 millisecond, 1,023,000 chips are generated every second. Related to the speed of light, the individual chips have a length of 300 m.

In C/A code mode, a position accuracy of +/-15 m is achieved.

Englisch: coarse/acquisition (GPS) - C/A
Updated at: 08.07.2019
#Words: 178
Links: code, satellite navigation, resolution, global positioning system (satellite comm.) (GPS), system
Translations: DE

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