基于多普勒变化率估计的载波跟踪算法

A Carrier Tracking Algorithm Based on Doppler Rate of Change Estimation

摘要:

为了改善卫星通信系统中，在低信噪比下对大动态的信号进行载波跟踪时，动态应力误差和热噪声引起的相位抖动使得信号解调损失明显的现象，提出了一种基于多普勒变化率估计的载波跟踪算法；首先通过延迟相关快速傅里叶变换（FFT）的方法和FFT分析的方法对接收信号的多普勒变化率和多普勒频率进行估计，然后利用估计值对接收信号进行多普勒变化率以及频率补偿，最后利用三阶锁相环对补偿后的信号进行跟踪，并在考虑符号速率的基础上，对该算法进行改进并仿真；仿真结果表明，在63dBHz的载噪比下，符号速率为1Mbps，跟踪变化率为150kHz/s时，使用该方法可以实现载波稳定跟踪，并且解调损失在0.3dB以内；该算法可以降低载波跟踪复杂度、提高跟踪精度，为接收机载波跟踪模块的改进提供了依据。

Abstract:

In order to improve the phase jitter caused by dynamic stress error and thermal noise in satellite communication system, the demodulation loss of the signal is obvious when tracking the carrier wave of the large dynamic signal at low SNR, in this paper, a carrier tracking algorithm based on Dopler rate of change estimation is proposed. First, the Dopler rate of change and Dopler frequency of the received signal are estimated by the method of delay-correlated Fast Fourier Transformation（FFT） and FFT analysis, then the Doppler rate of change and the frequency of the received signal are compensated by the estimated value, and finally the compensated signal is tracked by the third-order PLL, and the symbol rate is considered, the algorithm is improved and simulated. The simulation results show that this method can achieve stable carrier tracking with a symbol rate of 1 Mbps and a tracking rate of 150 kHz/s at a carrier-to-noise ratio of 63 dBHz, and the demodulation loss is less than 0.3 dB. By using this algorithm, the carrier tracking complexity can be reduced and the tracking precision can be improved, which provides a basis for the improvement of the carrier tracking module of the receiver.