Computation of Error Factors in GPS Signals

The earth's ionosphere acts as a perturbing medium on satellite-based navigational systems like GPS. Irregularities in the ionosphere due to space weather events caused by solar flares and coronal mass ejection can scatter Trans - Ionosphere radio signals producing fluctuations in both amplitude and phase and GPS cycle slips disrupting satellite communications and navigation. The ionosphere delay is one of the main sources of error in GPS precise positioning and navigation. The magnitude of the ionosphere delay is related to the Total Electron Content (TEC) along the radio wave path from a GPS satellite to the ground receiver. A dual-frequency GPS receiver can eliminate (to the first order) the ionosphere delay through a linear combination of L1 and L2 observables. The paper outlines a method allowing to compute the TEC with a precision of about 2�3 TECU and to detect Travelling Ionosphere Disturbances using GPS measurements.