A high-precision carrier synchronization algorithm based on FFT assistance

In the Global Navigation Satellite System (GNSS), BPSK is used as a carrier signal modulation method for navigation satellite transmission, and the navigation receiver can obtain navigation data by receiving and demodulating satellite signals. However, due to the relative motion between the receiver and the navigation satellite, the signal arriving at the receiving end will be introduced with Doppler frequency offset, which leads to the inability of the receiving end to achieve carrier synchronization correctly. In response to this issue, this paper proposes a combination algorithm of Doppler frequency offset estimation based on Fast Fourier Transform (FFT) and Doppler frequency offset estimation based on Phase Locked Loop (PLL). This algorithm can achieve compensation for large-scale Doppler frequency offset of BPSK modulated signals, and can also correct unknown phase offset in the signal itself. The experimental results show that when the signal-to-noise ratio (SNR) is greater than 1dB, the algorithm has high accuracy and carrier synchronization speed, which is very conducive to engineering implementation.