Two-dimensional compressed correlator for fast acquisition of CBOC-modulated signal in GNSS

Abstract

Long spreading code and CBOC (composite Binary offset carrier) modulated signals are exploited in the next-generation GNSS (global navigation satellite system) to improve the positioning performance. However, the acquisition process in a GNSS receiver can take more time than it does in a legacy GPS receiver due to the longer spreading code. This paper presents a CBOC TDCC (two-dimensional compressed correlator) for the fast acquisition of CBOC-modulated signals in Galileo E1. In TDCC for CBOC modulated signals, the signal power in the neighboring code phase and Doppler frequency hypotheses are coherently combined and tested to reduce the acquisition time in the first stage. In addition, the individual code phase and Doppler frequency hypotheses corresponding to the compressed hypotheses found in the first stage are searched in the second stage. The proposed CBOC TDCC outperforms the conventional acquisition technique in terms of the MAT (mean acquisition time).