Multifrequency, Multisatellite Vector Phase-Locked Loop for Robust Carrier Tracking

A new vector phase-locked loop (PLL) for joint tracking of carrier phase from all satellites on multiple frequencies is presented. It increases the robustness to ionospheric scintillations, carrier phase multipath and interference from jammer. The tracking error is split into a position error, a clock offset, ionospheric, and tropospheric errors which are filtered individually. The filter coefficients are optimized with orthogonal projections of the tracking error that eliminate the nuisance parameters. The tracking performance is determined recursively, and a significant reduction of the tracking error is observed during strong ionospheric scintillations with deep amplitude fades.