Implementation and Robustness Analysis of the Two-Step CBOC Tracking Algorithm in the scope of the GAMMA-A Project

Numerous mobile applications and services require that devices are aware of their location. Global Navigation Satellite Systems (GNSS) are the predominant enabling technology. But in order to deliver continuous and accurate location information provided by commercial GNSS, the satellite tracking process has to be stable and reliable in order to extract the pseudoranges for position computation. New families of navigation signals, such as AltBOC, CBOC and TMBOC bring potential improvements in the pseudorange calculation, including more signal power, better multipath mitigation capabilities and overall more robust navigation. GNSS signal tracking strategies also evolve comparing to traditional well-known tracking technique developed for BPSK modulation with prompt (P), early(E) and late(L) replicas in order to profit from the enhanced performance of the new signals. In this paper, the previously introduced E1 CBOC two-step tracking algorithm developed and implemented in the GAMMA-A FP7 project receiver [1] is analyzed with respect to tracking robustness and sensitivity. The implementation of this novel two-step tracking algorithm is described, and an analysis of the algorithm in realistic conditions versus the theoretical background is performed. The aim of this paper is therefore to investigate the robustness of the two-step tracking algorithm for E1 CBOC signal and in particular to investigate the DLL and PLL tracking loops performance when the power of the signal varies until the receiver loses the lock with the satellites.