Development and use of a GPS ionospheric scintillation monitor

Besides their intended use in radionavigation, global positioning system (G PS) satellite signals provide convenient radio beacons for ionospheric stud ies. Among other propagation phenomena, the ionosphere affects GPS signal p ropagation through amplitude scintillations that develop after radio waves propagate through ionospheric electron density irregularities. This paper o utlines the design, testing, and operation of a specialized GPS receiver to monitor L-band amplitude scintillations: the Cornell scintillation monitor . The Cornell scintillation monitor consists of a commercial GPS receiver d evelopment kit with its software modified to log signal strength from up to 12 channels at a high data rate (50 samples/s), Other features of the rece iver include the optional assignment of a channel to monitor the receiver n oise level in the absence of signal tracking and the means to synchronize m easurements between nearby independent receivers to perform drift measureme nts and correlation studies. The Cornell scintillation monitor provides cha racterization of the operational L-band scintillation environment and addit ionally permits study of the multipath environment of a static antenna. GPS scintillation monitors can provide information about the state of ionosphe ric irregularities for pure research purposes as well. Here their strength lies in the fact that they are inexpensive and compact and therefore can be readily proliferated. Even a single scintillation monitor can supplement r adar spatial coverage of irregularities in a limited way because it monitor s several satellite lines of sight simultaneously. This article introduces some of the potential of the scintillation monitor for research, primarily through examples associated with field testing the instrument.