Ionospheric scintillation measurements using the Global Positioning System

The Global Positioning System (GPS) uses dual-frequency transmissions to mitigate the ionospheric propagation delay bias. The accuracy of the group-delay correction is limited only by the rms errors in the individual group-delay measurements. The corresponding phase delay can be measured to a small fraction of an RF cycle. By simultaneously delay and Doppler tracking the GPS signals, absolute total electron content and phase scintillation can be measured. Results from a measurement campaign conducted at Ascension Island demonstrate the ionospheric scintillation monitoring capability of GPS and the performance of GPS monitor-station-type receivers in severe, naturally occurring scintillation. The results show that the first-order fading statistics can be accurately modeled. The second-order statistics are considerably more variable. Fades at 1575 MHz in excess of 10 dB for periods of several tenths of a second were commonly observed during the most disturbed periods.