Evaluation of Deep Signal Fading Effects Due to Ionospheric Scintillation on GPS Aviation Receivers

Deep and frequent GPS signal fading due to strong ionospheric scintillation is major concern for aircraft navigation in the equatorial region during solar maximum periods. Deep signal fading can break a receiver’s carrier tracking lock on a satellite channel and the satellite cannot be used for position solution until a receiver reacquires the lost channel. Frequent signal fading also causes frequent reset of the carrier smoothing filter of aviation receivers. Aviation receivers reduce code noise by as much as a factor of 10 by using carrier smoothing, but frequent loss of lock reduces the effective smoothing time and significantly increases the effect of code noise. This paper analyzes navigation availability during a strong scintillation period based on real scintillation data from the previous solar maximum. Both effects from satellite loss due to deep fading and shortened carrier