Design of GPS IF signal acquisition and tracking circuits based on FPGA

This paper presents a FPGA design of a novel GPS IF signal acquisition and tracking circuits, which acquires and tracks the GPS LI frequency and C/A code without FFT and Costas loop. The suggested acquisition circuit consists of 40 branches and each of which acquires 0.5 KHz bandwidth of GPS IF signal. The tracking circuit re-acquires the GPS IF signal based on the SV number and Doppler frequency offered by the acquisition circuit and then tracks the acquired signal by means of a simple dynamic local carrier jumping method proposed in this paper instead of the traditional Costas Loop based method. A unique data demodulation technique that is suitable for the carrier jumping method is also introduced to correctly recover the modulation data. Simulation results and FPGA test show that the proposed design works well for GPS IF signal acquisition and tracking and is promising for low cost and low power FPGA applications for GPS signal processing.