Scintillation of Global Positioning System Signal from the Ionosphere

The Global Positioning System receiver used for navigation on the Space Shuttle exhibited range rate noise which seems to have resulted from scintillation of the satellite signals by irregularities in ionospheric plasma. ... [ view full abstract ]

The Global Positioning System receiver used for navigation on the Space Shuttle exhibited range rate noise which seems to have resulted from scintillation of the satellite signals by irregularities in ionospheric plasma.  These effects have also been seen in the International Space Station.  The noise events cluster in geographic regions previously identified as susceptible to instability and disturbed ionospheric conditions. These mechanisms are reviewed in the context of the GPS observations. Range rate data continuously monitored during the free orbiting phase of several space shuttle missions revealed global scale distribution of ionospheric irregularities. Equatorial events cluster +/- 20 degrees about the magnetic equator and polar events exhibit hemispheric asymmetry suggesting influence of off axis geomagnetic polar oval system. The diurnal, seasonal and geographic distribution is compared to previous work concerning equatorial spread F, Appleton anomaly and polar oval. The observations provide a succinct demonstration of the utility of space based ionospheric monitoring using GPS. The susceptibility of GPS receivers to scintillation represent an unanticipated technical risk not factored into the selection of receivers for the United States space program.