A Study of Neuman Hoffman Codes for GNSS Application

The modernization of GPS and the potential deployment of GALILEO and COMPASS Global Navigation satellite system (GNSS) are fostered through the increasing demands for navigation and location services. Some innovations are realized to attain better performances over legacy GNSS. The adoption of secondary short synchronization codes, including Neuman Hoffman code, CS code and OC code, is one among these innovations, which play the important role on spectral separation, bit synchronization, and narrowband interference protection. In this paper, the merit of NH code is analyzed in detail. Using the I5 component of GPS L5 code, the acquisition method of NH code, which is under normal and weak signal, is analyzed respectively. The acquisition algorithms of I5 based on the zero-padding cascaded FFT approach is presented under normal signal conditions, the structure of quick acquisition of which is proposed. The flow of the combining method based on the block-accumulating coherent integration over extended interval cascaded FFT and cross correlation mitigation approach is proposed under weak signal conditions.