A Study on the code acquisition and tracking systems using pseudo-ternary M-sequences

In this paper, a code acquisition and tracking system using pseudo-ternary maximum-length shift register sequence (pseudo-ternary M-sequence) is proposed. The pseudo-ternary M-sequence is based on the M-sequence and generated by very simple methods. In the code tracking part of the proposed system, a delay-locked loop (DLL) referring the pseudo-ternary M-sequence is used. The DLL using the pseudo-ternary M-sequence can improve a tracking error performance by comparison with the DLL using the M-sequence. In the code acquisition part, a rectified pseudo-ternary M-sequence and the {-1,+1}-valued M-sequence are used. Because of the rectification, the proposed system realizes an acquisition scheme that is independent of polarity of a received sequence. Moreover, since a cross-correlation function of the pseudo-ternary M-sequence and the {-1,+1}-valued M-sequence shows a pseudo-orthogonal relation, a probability of a false alarm of the proposed system can be smaller than the conventional sliding correlator using Manchester-coded M-sequences.