Characterization of The Ionospheric Scintillation at High Latitude Using GPS signal: Investigating the Behaviour of the Entropy of the Signal

Abstract:

Transionospheric radio signals experience both amplitude and phase variations as a result of propagation through a turbulent ionosphere; this phenomenon is known as ionospheric scintillations. As a result of these fluctuations, GPS receivers lose track of signals and consequently induce position and navigational errors. Therefore, there is a need to study these scintillations and their causes in order to not only resolve the navigational problem but in addition develop analytical and numerical radio propagation models.
We investigate the multi-fractal structure of the turbulent ionospheric plasma by analyzing the L1 GPS signal at 50 Hz sampling rate using the Canadian High Arctic Ionospheric Network (CHAIN) measurements. We consider the power fluctuations of the signal. Differential signal is constructed for different time lags, the distribution of the differential signal is non-Gaussian, this is believed to be the result of the non-linearity of the system. In order to take into account the non-linear aspect we fit the Probability Density Function to the Castaing distribution, this latter allows the variance of the distribution to vary by assuming a log-normal distribution of the variance convoluted with a Gaussian distribution. The intermittency of the signal is considered by estimating the flatness of the distribution (or Kurtosis) that is the fourth normalized moment of the PDF. It has been found that the intermittency is predominant for small scales.
The second problem tackled is the optimization of the detrending frequency which delimit the scintillation contribution from the slow variation of the signal due to the ionospheric background variability and the motion of the GPS satellite. In order to achieve this characterization we investigate the behavior of the entropy of the system for various temporal scales, this multi-scale analysis is performed using the wavelet analysis technique.