Unambiguous BOC Acquisition in Galileo Signal

Galileo will be Europe’s own Global Navigation Satellite System (GNSS), which is aiming to provide highly accurate and guaranteed positioning services. Among several services for separate target groups, Galileo Open Services (OS) are designed for mass-markets, and they will be available worldwide and free of charge for all users. Galileo E1 system has a code period of 4ms which is quadruple that of GPS C/A code. In other words, due to the large number of hypotheses in code phase at acquisition stage, a longer searching time or more hardware resource is required and a dual estimate receiver of binary offset carrier (BOC) signals for Galileo system applications is described. It is difficult to acquire Galileo signal because of longer code length and the autocorrelation function (ACF) of BOC modulation. In this paper, we use cyclically shiftand-combine (CSC) and BPSK-like architectures the impact of unambiguous acquisition algorithms for BOC modulation, and that proposed method acquires these satellite signals with hardware complexity reduction. The underlying concept in the method is to modify the code structure and shorten the code period such that the acquisition complexity can be decreased, but the orthogonality of the modified code will not be as good as the original code anymore. In the most cases of this paper, the performance degradation is acceptable when mean acquisition time is used as a performance metric. Simulation results show that our proposed search algorithm can provide better performance with low hardware complexity for acquiring these satellite signals and possible wrong peak selection in the low signal-to-noise ratio (SNR) conditions. KeywordsAcquisition; Ambiguous; BOC; BPSK-like; CSC; Galileo