Study of carrier tracking for high dynamic M-ary spread spectrum signals

High dynamic condition will cause Doppler shift acutely, then digital carrier loop may fail to track signal and wrong demodulation may occur, For the problem of carrier acquisition and tracking of high-dynamic M-ary spread spectrum signals, utilizing the characteristics that the dynamics of the signal can be removed by FLL, and the phase can be tracked precisely by PLL. In this paper, the implementation of the structure adopts the algorithms of cross-product auto frequency tracking (CPAFC) and Four-Quadrant Frequency Discriminator and the digital Costas loop to achieve carrier tracking. Theory analysis and simulation results show that this method can realize the carrier tracking quickly and precisely under high dynamic circumstance.