Piece-wise control approaches to improving GPS signal reacquisition

Two piece-wise approaches are proposed and tested, including the method of a piece-wise Frequency-locked Loop (FLL) followed by a piece-wise Phase-locked Loop (PLL) and the method of a direct piece-wise PLL. The performance of each approach was assessed using GPS data collected on a vehicle-based mobile platform under mild to moderate operational conditions. Both piece-wise methods were shown to be able to reduce the transition time by a factor of approximately three for the frequency pull-in period and four for the phase pull-in period. Finally, the scheme of piece-wise FLL followed by piece-wise PLL is recommended to reduce the reacquisition time during the carrier phase reacquisition process.