基于插值DFT相位差的VDES信号频偏估计算法

Frequency Offset Estimation Algorithm of VDES Signals Based on Interpolation DFT Phase Difference

针对VDES系统中存在大范围多普勒频偏的问题,提出了一种基于插值DFT相位差的VDES信号频偏估计算法。首先在理论上分析了DFT相位差算法的估计误差,仿真发现其性能受频偏相对偏差影响严重,针对此缺点提出在计算相位差之前设置频偏相对偏差门限值,在门限值前后综合利用Quinn插值和Rife插值两方法对频偏相对偏差进行预估计,以此消除频偏相对偏差对估计性能的影响。仿真实验结果表明:该算法的频偏估计性能稳定,且精度接近克拉美罗界,可用于VDES接收机。

In order to solve the wide-range frequency offset problem of VHF Data Exchange System,a frequency offset estimation algorithm of VDES signals based on interpolation DFT phase difference was proposed.Firstly,the error of DFT phase difference algorithm is analyzed in theory.The simulation results show that the performance of DFT phase difference algorithm is seriously affected by the relative deviation of frequency offset.Then in order to overcome this shortcoming,a threshold value of relative deviation of frequency offset is set before calculating phase difference,and the relative deviation of frequency offset is estimated by Quinn interpolation and Rife interpolation before and after the threshold value.Thus,the influence of the relative deviation frequency offset on the estimation performance is eliminated.The simulation experiment results show that the performance of frequency offset estimation is very stable,and the accuracy of the algorithm is close to the Cramer-bound,which can be used in VDES receiver.