From figure 1, narrow bandwidth baseband signals (containing the navigation and almanac data) is modulated with a PRN code so that the spectrum of the baseband signal becomes significantly wide.Īfter the spread spectrum process of the baseband signals, the spread signals are modulated using binary phase-shift keying (BPSK) modulation method. The spread spectrum is performed by modulating the narrow bandwidth signal with a pseudo-random noise (PRN) code that has a special correlation property.įigure 1 below shows the steps to generate GPS L1 C/A signals. The spread spectrum modulation increases the bandwidth of the baseband signals. The generation of GPS L1 C/A signals passes several steps including a spread spectrum modulation of the GPS baseband signals. The main benefits of spread spectrum communication, for example, are multiple-access communication, natural and artificial interference resistance, secure communication and others. Spread spectrum communication is a type of communication where the baseband (narrow bandwidth) of transmitted signals are intentionally spread in frequency domain so that the signal has a wider bandwidth than the baseband bandwidth.

With the spread spectrum communication, multiple-accesses of the GPS signals can be performed. Global positioning system (GPS), or in general global navigation satellite system (GNSS) is a type of spread spectrum communication. The C/A code implementation in MATLAB and C/C++ are presented as well. In this post, C/A codes for GPS signals generation will be discussed.

Linear feedback shift register matlab