Measuring Ionospheric Scintillation Effects from GPS Signals

GPS signals provide an excellent means for measuring ionospheric scintillation effects on a global basis because the signals are continuously available and can be measured through many points of the ionosphere simultaneously. GPS signals are themselves affected. However, tracking through disturbances with a GPS receiver is usually possible with reasonably wide bandwidth tracking loops. Because of this, ionospheric scintillation can be monitored, and is currently being monitored around the world. This was not widely possible during the last solar activity peak. The importance of the wide bandwidth is that scintillation parameters, such as spectral content, can be computed, not just the effects of the scintillation on GPS receiver performance. The majority of the current wide bandwidth monitoring is being done using a commercially off-the-shelf GPS receiver implemented with special software -- the GSV4000 GPS Ionospheric Scintillation Monitor (GISM) and predecessor prototype units. Now, GPS Silicon Valley is pleased to offer the new GSV4004 GPS Ionospheric Scintillation and TEC Monitor (GISTM) receiver. This receiver, a NovAtel EURO4 dual-frequency receiver with special firmware, comprises the major component of a GPS signal monitor, specifically configured to measure amplitude and phase scintillation from the L1 frequency GPS signals, and the ionosphere's TEC from the L1 and L2 frequency GPS signals. This scintillation and TEC monitoring receiver is housed in a NovAtel GPStation4E housing with a low phase noise oscillator, and provides true amplitude, single frequency carrier phase measurements and TEC measurements of up to 11 GPS satellites in view. It will also track one SBAS (WAAS, EGNOS or MSAS) satellite, providing L1 measurements and data, as the 12th satellite. The unit comes with complete software that allows the automatic measurement and computation of all the major scintillation parameters and TEC. A variety of antennae, with or without choke rings and cables, are offered as options. In this paper, the wide bandwidth monitoring capabilities of these receivers are described. This is followed by the presentation of data collected from a selection of recorded scintillation events and TEC calibration results.