一种高动态低信噪比下载波快速捕获跟踪方法

针对高动态、低信噪比的接收信号，首先对整个多普勒频率范围进行分段，并在每一段内利用本地产生的带有多普勒频率变化率的复信号来抵消接收信号中多普勒频率变化率的影响，然后在每一段内利用FFT（FastFourierTransform，快速傅里叶变换）进行载波频率并行捕获，从而同时完成载波多普勒频率及其变化率的初步估计。利用载波多普勒频率及其变化率估计信息辅助锁频环快速入锁，进而利用锁频环辅助三阶锁相环完成载波信号的锁频锁相跟踪。使用这种方法，可以快速获取信号的多普勒频率及其变化率信息，并且在极短时间内完成载波的稳定跟踪，使接收设备具备快速捕获跟踪大动态弱信号的能力。

A Method for Fast Acquisition and Tracking of High Dynamic and Low SNR Carriers

To meet requirements for acquisition of high dynamic and low SNR （Signal-to-Noise Ratio） carrier sig- nals, the Doppler range is divided into numerous sections and locally generated complex signals with Doppler＇s rate are used to cancel the influence of Doppler rate in the receive signals in each section. Then, FFT （Fast Fourier Transform） is used in every section to analyze the Doppler frequency and perform acquisition, thus providing initial estimates of the carrier Doppler frequency and its variation rate at the same time. The estimates are used for fast loc- king of FLL （Frequency Locked Loop）, which is then used to assist the third-order PLL （Phase-Locked Loop） for tracking of the carrier signals. The method is used for fast acquisition of the Doppler frequency and its variation rate and for stable tracking of the carriers within a very short time. As a result, receive equipment is capable of fast ac- quisition and tracking of high dynamic and low SNR signals.