一种适用于多普勒高阶变化率的载波跟踪算法

针对多普勒高阶变化率的载波跟踪问题，分析了现有二阶锁频环辅助三阶锁相环的局限之处，设计了一种三阶锁频环辅助四阶锁相环的载波跟踪算法，从理论上证明了该算法可以对多普勒高阶变化率信号进行无误差跟踪，并根据环路传递函数和环路带宽，推导出了环路所有参数的计算方法，最后通过环路模式切换及环路带宽设置策略，既加快了整个载波跟踪环路的收敛速度，又提高了载波频率跟踪精度，保证了跟踪的稳定性。仿真结果表明，对于多普勒高阶变化率信号，该算法能够有效地完成信号的载波跟踪并正常解调出原始数字信息，因此有较高的应用价值。

A carrier tracking algorithm applicable for Doppler high-order rate

The limitations of the existing second-order frequency-locked loop aided third-order phase-locked loop are analyzed and a carrier tracking algorithm of third-order frequency-locked loop aided fourth-order phase-locked loop is designed for carrier tracking of Doppler high-order rate. It is proved theoretically that this algorithm can track the signal with Doppler high-order rate without error. Then, the calculation method of all loop parameters is deduced according to the loop transfer function and the loop bandwidth. Finally, switching strategy of loop mode and setting strategy of loop bandwidth are adopted to accelerate the convergence speed of the whole carrier tracking loop, improve the carrier frequency tracking accuracy and ensure the tracking stability. The simulation results show that this algorithm can complete carrier tracking effectively and demodulate the original digital information normally for the signal with Doppler high-order rate. So it will have rather high importance in practical applications.