基于最大似然原理的低复杂度频率检测器

Simplified version of frequency detector derived from the maximum-likelihood principle

在研究Gardner提出的最大似然检测器(MLFD)及其相关简化方法的基础上,提出了一种基于最大似然原理的低复杂度的频率检测器.采用非等间隔的阶梯加权函数取代了MLFD中的线性加权函数.通过计算机仿真,分析了该检测器的频率捕获性能和稳态抖动性能.分析结果显示,所提出的FAFD频率检测方法相对于RCFD具有较高的检测增益和较低的自噪声功率,在显著降低MLFD的实现复杂度的情况下,并未明显降低其检测性能.FAFD频率检测器可以应用于存在较大归一化频偏的通信接收机的自动频率控制环路中.

A reduced-complexity frequency detector derived from maximum-likelihood principle is presented after studying Gardner＇s maximum likelihood frequency detector（MLFD） and correlative simplified methods. It uses a fragmental ladder function to substitute a linear function of MLFD. The frequency detection performance and self-noise properties were analyzed by computer simulation. The result shows that the detector presented in this paper has higher frequency detecting gain and lower self noise power than RCFD （reduced complexity frequency detector）, and it substantially reduces the realization complexity of MLFD without significantly degrading the performance. The detector can be used in adaptive frequency control loop of the receiver which has a big normalized frequency offset.