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This paper analyzes the carrier tracking outputs of GPS L1 signals during ionosphere scintillations using a conventional PLL, a frequency-assisted PLL, and a Kalman filter based PLL. The data used in the analysis were collected by a radio frequency front end at Ascension Island in March 2001. Among the 8 GPS satellites in view during the 45 minutes data collection experiment, 6 of them experienced phase fluctuations while 7 of them showed signs of amplitude scintillation. The paper presents the detailed tracking algorithm implementations, tracking loop generated carrier to noise ratio and S4 index, detrended carrier phase measurements, and spectral analysis of both signal intensity and the detrended carrier phase for all SV in view during scintillations.