Abstract:

The time varying plasma sheath can potentially degrade electromagnetic systems through increasing time varying amplitude attenuation and phase fluctuation. The BPSK modulated GPS signals could be affected by phase fluctuation. Utilizing electron density and collision frequency provided by NASA, transmission coefficient is calculated by using the scattering matrix method and phase fluctuation characteristic is obtained. GPS signal affected by phase fluctuation are acquired by the Hilbert method. Then by means of Electromagnetic propagation theory and GPS software receiver, the effects of phase fluctuation caused by plasma sheath on GPS signal and its positioning before there occurs blackout are analyzed. Results show that the effect on positioning accuracy is closely related to the variance of phase fluctuation. When the calculated variance is 0.1142, the maximal percentage of variation larger than 5m is up to 14% and the percentage larger than 10m is up to 1.5%.

Key words: Plasma sheath, Time varying, Scattering matrix method, Phase fluctuation, GPS positioning