Research Of Method To Extract Ionospheric S₄ Index Based On Navigation Signals

Ionospheric scintillations are rapid variations in the amplitude and phase of radiosignals resulting from density irregularities in the ionosphere. Ionosphericscintillations may influence adversely the performance of satellite communicationsystem and the precision of navigation system. In recent years, space weathermonitoring and forecasting are more essential with the rapid development of spacetechnology and aerospace needs. The monitoring and forecasting of ionosphericscintillations becomes an important subject in this field. Currently, it is very necessaryto carry out observation and research on ionospheric scintillations from space weathermonitoring and forecasting, or from the ionospheric scintillation region characteristics.Therefore, it is an important work to develop new information retrieval methods onionospheric scintillations, which provide a theoretical and experimental basis for thedevelopment of Chinese independent ionospheric scintillations monitoring equipment.In this paper, some issues were discussed in the following:Firstly, Tracking and acquisition of GPS signals and the traditional methods ofextracting ionospheric scintillations information were discussed. The performance oftraditional methods was analyzed, and a correction method was advanced.Secondly, a new method for acquiring ionospheric scintillations informationbased on software GPS receiver was proposed. It is hard for the traditional GPSreceiver to acquire signal or maintain continuously tracking if the GPS signal is weak.It causes the receiver not to monitor ionospheric scintillations continuously. In order to solve this problem, a new computational method, Fast Fourier TransformAlgorithm (FFT) processing in the frequency domain, was proposed in this paper.Correspondingly, regarding to the error of the S4 index, a new correction method,which was very simple and direct, was proposed.Finally, the methods above were tested with the data collected in the experiments.The result indicated that the new methods were feasible and reliable.The research work of this paper provides theoretical foundations and experimentalpreparations for the ionospheric scintillations monitoring equipment independently forfuture studies.