Data-Driven Testbed for Evaluating GPS Carrier Tracking Loops in Ionospheric Scintillation

A large set of equatorial ionospheric scintillation data has been compiled, used to characterize features of severe scintillation that impact Global Positioning System phase tracking, and used to develop a scintillation testbed for evaluating tracking loops. The data-driven testbed provides researchers a tool for studying, and the receiver developers a tool for testing, the behavior of carrier tracking loops under realistic scintillation conditions. It is known that severe equatorial scintillation causes cycle slipping and, in the worst cases, complete loss of carrier lock. Testbed results indicate that cycle slips are primarily caused by the abrupt, near half-cycle phase changes that occur during the deep power fades of severe equatorial scintillation. For a class of standard tracking loops, parameter values that minimize scintillation-induced cycle slipping are identified.