锁相环与锁频环在数字Costas环中的应用

基于锁相环和锁频环的模型,研究了由两者构成的数字Costas环结构和性能.首先介绍了传统的数字Costas环模型,接着给出了鉴相器、二阶环路滤波器和三阶环路滤波器的结构,在此基础上分析了基于锁频环的数字Costas模型,实现了扩大Costas环的跟踪范围和提高跟踪精度的目的,最后给出了仿真结果,分析了两种环路单独和相结合后的应用和特点.

Application of PLL and FLL in the Digital Costas Loop

Based on the model of phase-locked loop(PLL) and frequency-locked loop(FLL),structure and properties of digital Costas loop are researched in this paper. Firstly, the traditional model of the digital Costas loop is introduced. Then, structures of phase detector, 2nd-order loop filter and 3rd-order loop filter are given. Based on the above, the model of digital Costas loop based on FLL is analyzed,which achieves the expansion of the tracking range and the purpose of improving tracking accuracy. Finally, simulation results is given and then , applications and features for separated and mixed of above two loops are analyzed. Key words: digital costas loop; PLL; FLL; loop filter