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针对航天测控对载波快速捕获的需求,设计一种能够实现载波快速捕获的方法,即先对导频信号进行频率估计,再将估计得到的频率值置入后续的科斯塔斯环进行处理。Rife频率估计方法的估计误差接近克拉美-罗限,但是当信噪比较低或载波频率在频率分辨率整数倍附近时,此方法有较大的估计误差。为了提高导频信号的频率估计精度,采用修正Rife(M-Rife)频率估计方法。对M-Rife频率估计方法的性能进行仿真分析,并与Rife频率估计方法进行对比,结果表明M-Rife频率估计方法可以有效地提高频率估计精度和稳定度。
Aiming at the demand of carrier rapid acquisition by aerospace monitoring and control, a method of fast carrier acquisition is designed, that is, the pilot signal is first estimated and then the estimated frequency is placed into the subsequent Costas loop. The estimation error of the Rife frequency estimation method is close to that of the Kramera-Rauer limit, but this method has a large estimation error when the signal-to-noise ratio is low or the carrier frequency is an integral multiple of the frequency resolution. In order to improve the frequency estimation accuracy of the pilot signal, a modified Rife (M-Rife) frequency estimation method is adopted. The performance of the M-Rife frequency estimation method is simulated and compared with the Rife frequency estimation method. The results show that the M-Rife frequency estimation method can effectively improve the frequency estimation accuracy and stability.