The carrier-tracking algorithm is based on AFC. With the switching between wide and narrow FLL , the carrier-tracking loop can achieves good performance whether frequency changes in high dynamic range or it is in stable state.

• 载波跟踪采用AFC(自动频率控制)跟踪频率变化,宽窄两通道AFC切换方式既可以适应动态条件下的载波跟踪,又能保证稳态条件下对载波频率的精确估计。