An improved two-stage fast acquisition method based on FFT

The navigation enhancement signals in communication and navigation integration signals are characterized by limited spectrum resources and non-continuous transmission. For the high-dynamic, short-burst navigation enhancement signals in the L-band of low-earth orbit (LEO) satellites, an improved segmented Fast Fourier Transform (FFT) two-stage time-frequency domain two-dimensional rapid acquisition method is proposed. Through the two-stage segmented coherent FFT acquisition process, the arrival time of the navigation enhancement signal and the signal Doppler shift estimation are obtained simultaneously, enabling fast and real-time signal acquisition processing in LEO scenarios. Simulation results demonstrate that when the signal carrier-to-noise ratio is above 48 dBHz, the rapid acquisition algorithm can adapt to signal Doppler shifts of ±40 kHz and accommodate short-burst transmission modes, with the signal Doppler estimation error controlled within ±80 Hz and the signal arrival time estimation error controlled within ±1 chip.