A novel quasi open loop frequency estimator for GNSS signal tracking

The problem of designing the robust architectures for tracking the global navigation satellite system (GNSS) signals in harsh environments has gained immense attraction. The classical closed loop architectures like phase locked loop (PLL) have been used for many years for tracking purposes but for challenging applications their design procedure becomes intricate. This paper proposes and demonstrates the use of a quasi-open loop architecture to estimate the time varying carrier frequency of the GNSS signal. It is shown via simulation results that use of such type of scheme provides an additional degree of freedom for designing the whole architecture. Specially, we have shown that we can ease the design of the loop filter in harsh environments if we have this additional degree of freedom.