Abstract: The conventional tracking loops in GPS receivers usually lose locked high dynamic signals.Thus，to achieve better FLL performance in dynamic situations and higher PLL measurement accuracy，we implemented a second order FLL in an assisted third order PLL(FPLL) based carrier trackingloop. These methods were employed to analyze the measurement accuracy FPLL of code and carrierphases，and implemented on our software receiver platform with Matlab. FPLL was tested using thedata collected through Spirent GSS7700 simulator. The results show that the average measurementaccuracy for code the phase and carrier phase was 1.31 m(1?) and 4. 24 X 10-3m/s(1?)，respectively， as the signals are around 40 dB/Hz of SNR(signal to noise ratio)，with 26 g of acceleration and9 g/s of jerk.