扩频信号跟踪环路中的锁频环研究

Study of Frequency-Locked Loops for Tracking Spread Spectrum Signals

为了正确地接收扩频应答机的高动态信号,接收机需要很宽的频率跟踪范围。二阶锁频环,因其对频率斜升信号的频率跟踪误差为0而广泛应用于扩频信号的跟踪环路。在详细分析了具有四象限反正切鉴频器的二阶锁频环的噪声特性、频率跟踪范围的基础上,通过仿真得到了最优环路带宽。整个分析和推导过程及结论对扩频信号跟踪环路的设计和优化具有很好的参考价值。

A wide frequency tracking range is required for receivers to accurately acquire spread spectrum signals.The second order frequency-locked loops（FLL） are generally used in spread spectrum tracking loops because of zero frequency tracking error for Doppler rate signals.The noise performance and frequency pull-in range of a second order FLL with four quadrant arctangent discriminator are discussed and deduced in this paper.And the optimum bandwidth of the tracking loop is calculated and simulated by MATLAB.The derivation and results are valuable for loop design and optimization.