Open Loop Performance Of Gnos Under Severe Ionospheric Scintillation

With the development of space explorations, ionospheric scintillation, which poses hazard to the radio system, starts to concern the scientists.Global Navigation Satellite System Occultation Sounder (GNOS) is the first operational occultation sounder of China [1]. The open loop (OL) mode of GNOS gives GNOS the ability to track signals under severe scintillation. The OL mode uses the positioning results and climatology model to predict the frequency of the signal. And the performance of prediction will not be affected by the degradation and vibration of signals. Hence, OL mode has great potential to monitor the ionospheric scintillation.The measurements of OL mode are predicted carrier phase, in-phase and quadrature (I/Q) components of signal. In order to calculate the scintillation indexes, we need to recover signal power from I/Q components, eliminate navigation data modulation (NDM) in I/Q components, reconstruct carrier phase from no NDM I/Q components.In this paper, GNOS OL data is post-processed to calculate the scintillation indexes. Results of GNOS are compared to the results of commercial scintillation monitor to illustrate the advantages of GNOS OL mode.