基于数字锁相环的扩频接收机载波同步技术研究

为了解决扩频接收机中所引入的多普勒频移为载波跟踪带来的困难,本文提出了一种基于FLL/PLL相结合的载波跟踪方法,充分发挥了载波频率跟踪环(FLL)动态性能好和载波相位跟踪环(PLL)跟踪精度高的优点,并且利用了基于CORDIC算法的反正切鉴相方法。与反正切近似算法相比,CORDIC算法具有更高的精度。仿真图给出了输入信噪比为0到10dB时环路频偏跟踪和相位跟踪的均方根误差值。从图中可以看出,输入信噪比越高,跟踪的精度越高。仿真结果表明,该方法能快速、精确地实现载波跟踪。

Study on Carrier Synchronization of Spread Spectrum Receiver based on Digital Phase-Locked Loop

In order to solve the problem of carrier tracking from the Direct Sequence Spread Spectrum （DSSS） receiver in Doppler shift environment, a method of carrier tracking, which combining FLL with PLL, is presented in this paper, It makes use of the good dynamic performance of FLL and high tracking accuracy of PLL. A phase detector based on the CORDIC algorithm is used to implement the aretan function. Compared with the approximation algorithm for arctan function,CORDIC algorithm has a higher precision. The simulation diagram indicates the rms frequency error and rms phase error with the input SNR from 0 to 10dB. It can be found that the higher the input SNR the higher the tracking accuracy will be. The simulation results also show that the proposed method will make carrier tracking quick and accurate.