GPS Carrier Phase Spectrum Estimation for Ionospheric Scintillation Studies

Abstract

GPS signal carrier phase spectrum is an important measure of ionospheric scintillations. The conventional means of obtaining the carrier phase spectrum is by performing an FFT of the detrended carrier phase estimation generated by the carrier phase lock loop (PLL). The PLL is a feedback system whose outputs are influenced by the system parameters and are not true representations of the input phase. In this paper, we use simulated GPS scintillation signals to demonstrate the distortion of the input carrier phase spectrum by the PLL and receiver noise. An inverse filter and mean high frequency power subtraction operation are cascaded following the PLL to restore the original input carrier phase spectrum. The carrier phase spectrum restoration method performance is evaluated using both simulated and real scintillation signals and its limitation is also addressed. Copyright © 2013 Institute of Navigation.