Kalman Filter Based Robust GNSS Signal Tracking Algorithm in Presence of Ionospheric Scintillations

摘要

Ionospheric scintillations are created by diffraction when the transmitted propagating waves encounter a medium made of irregular structures with variable refraction indexes. The recombination of the waves after propagation can be constructive or destructive and the resulting signal at output of the receiver antenna may present rapid variations of phase and amplitude. Scintillations are essentially observed in the regions located under the geomagnetic equator, where irregularities in the ionosphere like plasma bubbles occur more frequently. They also happen over Polar Regions and are associated with the penetration of charged particles along the magnetic field lines. Under the auroral oval region, scintillations can be local or spread over a great part of the oval. According to past observations scintillations occur mainly at the period of the equinox and the solstice. During the rest of the time there are almost no observations. After sunset, the modification in the ionosphere layers generates such variations. Scintillations cause very brutal and fast fades of the received signal, and once these phenomena occur they can last from 30 minutes up to several hours.